Chapter 1. Differential Diagnosis Step by Step
The process of DSM-5 differential diagnosis can be broken down into six basic
steps: 1) ruling out Malingering and Factitious Disorder, 2) ruling out a substance
etiology, 3) ruling out an etiological medical condition, 4) determining the
specific primary disorder(s), 5) differentiating Adjustment Disorder from the
residual Other Specified and Unspecified conditions, and 6) establishing the
boundary with no mental disorder. A thorough review of this chapter provides a
useful framework for understanding and applying the decision trees presented in
the next chapter.
Step 1: Rule Out Malingering and Factitious Disorder
The first step is to rule out Malingering and Factitious Disorder because if the
patient is not being honest regarding the nature or severity of his or her
symptoms, all bets are off regarding the clinician’s ability to arrive at an accurate
psychiatric diagnosis. Most psychiatric work depends on a good-faith
collaborative effort between the clinician and the patient to uncover the nature
and cause of the presenting symptoms. There are times, however, when
everything may not be as it seems. Some patients may elect to deceive the
clinician by producing or feigning the presenting symptoms. Two conditions in
DSM-5 are characterized by feigning: Malingering and Factitious Disorder. These
two conditions are differentiated based on the motivation for the deception.
When the motivation is the achievement of a clearly recognizable goal (e.g.,
insurance compensation, avoiding legal or military responsibilities, obtaining
drugs), the patient is considered to be Malingering. When the deceptive behavior
is present even in the absence of obvious external rewards, the diagnosis is
Factitious Disorder. Although the motivation for many individuals with
Factitious Disorder is to assume the sick role, this criterion was dropped in DSM5 because of the inherent difficulty in determining an individual’s underlying
motivation for his or her observed behavior.
The intent is certainly not to advocate that every patient should be treated as a
hostile witness and that every clinician should become a cynical district attorney.
However, the clinician’s index of suspicion should be raised 1) when there are
clear external incentives to the patient’s being diagnosed with a psychiatric
condition (e.g., disability determinations, forensic evaluations in criminal or civil
cases, prison settings), 2) when the patient presents with a cluster of psychiatric
symptoms that conforms more to a lay perception of mental illness rather than to
a recognized clinical entity, 3) when the nature of the symptoms shifts radically
from one clinical encounter to another, 4) when the patient has a presentation
that mimics that of a role model (e.g., another patient on the unit, a mentally ill
close family member), and 5) when the patient is characteristically manipulative
or suggestible. Finally, it is useful for clinicians to become mindful of tendencies
they might have toward being either excessively skeptical or excessively gullible.
Step 2: Rule Out Substance Etiology (Including Drugs
of Abuse, Medications)
The first question that should always be considered in the differential diagnosis is
whether the presenting symptoms arise from a substance that is exerting a direct
effect on the central nervous system (CNS). Virtually any presentation
encountered in a mental health setting can be caused by substance use. Missing a
substance etiology is probably the single most common diagnostic error made in
clinical practice. This error is particularly unfortunate because making a correct
diagnosis has immediate treatment implications. For example, if the clinician
determines that psychotic symptoms are due to Cocaine Intoxication, it usually
does not make sense for the patient to immediately start taking an antipsychotic
medication unless the psychotic symptoms are putting the patient (or others) in
immediate danger. The determination of whether psychopathology is due to
substance use often can be difficult because although substance use is fairly
ubiquitous and a wide variety of different symptoms can be caused by substances,
the fact that substance use and psychopathology occur together does not
necessarily imply a cause-and-effect relationship between them.
Obviously, the first task is to determine whether the person has been
using a substance. This entails careful history taking and physical examination
for signs of Substance Intoxication or Substance Withdrawal. Because substanceabusing individuals are notorious for underestimating their intake, it is usually
wise to consult with family members and obtain laboratory analysis of body fluids
to ascertain recent usage of particular substances. It should be remembered that
patients who use or are exposed to any of a variety of substances (not only drugs
of abuse) can and often do present with psychiatric symptoms. Medicationinduced psychopathology is more and more common, and very often missed,
especially as the population ages and many individuals are taking multiple
medications. Although it is less common, toxin exposure should be considered,
especially for people whose occupations bring them into contact with potential
toxins.
Once substance use has been established, the next task is to
determine whether there is an etiological relationship between it and
the psychiatric symptomatology. This requires distinguishing among three
possible relationships between the substance use and the psychopathology: 1) the
psychiatric symptoms result from the direct effects of the substance on the CNS
(resulting in diagnosis of Substance-Induced Disorders in DSM-5; e.g., CocaineInduced Psychotic Disorder, Reserpine-Induced Depressive Disorder); 2) the
substance use is a consequence (or associated feature) of having a primary
psychiatric disorder (e.g., self-medication); and 3) the psychiatric symptoms and
the substance use are independent. Each of these relationships is discussed in
turn.
1. In diagnosing a Substance-Induced Disorder, there are three
considerations in determining whether there is a causal
relationship between the substance use and the psychiatric
symptomatology. First, you must determine whether there is a close
temporal relationship between the substance or medication use and the
psychiatric symptoms. Then, you must consider the likelihood that the
particular pattern of substance/medication use can result in the observed
psychiatric symptoms. Finally, you should consider whether there are
better alternative explanations (i.e., a non-substance/medication-induced
cause) for the clinical picture.
o You should consider whether a temporal relationship exists
between the substance/medication use and the onset or
maintenance of the psychopathology. The determination of whether
there was a period of time when the psychiatric symptoms were
present outside the context of substance/medication use is probably
the best (although still fallible) method for evaluating the etiological
relationship between substance/medication use and psychiatric
symptoms. At the extremes, this is relatively straightforward. If the
onset of the psychopathology clearly precedes the onset of the
substance/medication use, then it is likely that a nonsubstance/medication-induced psychiatric condition is primary and
the substance/medication use is secondary (e.g., as a form of selfmedication) or is unrelated. Conversely, if the onset of the
substance/medication use clearly and closely precedes the
psychopathology, it lends greater credence to the likelihood of a
Substance-Induced Disorder. Unfortunately, in practice this
seemingly simple determination can be quite difficult because the
onsets of the substance/medication use and the psychopathology
may be more or less simultaneous or impossible to reconstruct
retrospectively. In such situations, you will have to rely more on
what happens to the psychiatric symptoms when the person is no
longer taking the substance or medication. Psychiatric symptoms
that occur in the context of Substance Intoxication, Substance
Withdrawal, and medication use result from the effects of the
substance or medication on neurotransmitter systems. Once these
effects have been removed (by a period of abstinence after the
withdrawal phase), the symptoms should spontaneously resolve.
Persistence of the psychiatric symptomatology for a significant
period of time beyond periods of intoxication or withdrawal or
medication use suggests that the psychopathology is primary and not
due to substance/medication use. The exceptions to this are
Substance/Medication-Induced Major or Mild Neurocognitive
Disorder, in which by definition the cognitive symptoms must persist
after the cessation of acute intoxication or withdrawal or medication
use, and Hallucinogen Persisting Perception Disorder, in which
following cessation of use of a hallucinogen, one or more of the
perceptual symptoms that the individual experienced while
intoxicated with the hallucinogen (e.g., geometric hallucinations,
flashes of color, trails of images of moving objects, halos around
objects) are reexperienced. The DSM-5 criteria for
substance/medication-induced presentations suggest that
psychiatric symptoms be attributed to substance use if they remit
within 1 month of the cessation of acute intoxication, withdrawal, or
medication use. It should be noted, however, that the need to wait 1
full month before making a diagnosis of a primary psychiatric
disorder is only a guideline that must be applied with clinical
judgment; depending on the setting, it might make sense to use a
more extended duration or a shorter duration depending on your
concern for avoiding false positives versus false negatives with
respect to detecting a substance/medication-induced presentation.
Some clinicians, particularly those who work in substance use
treatment settings, are most concerned about the possibility of
misdiagnosing a substance/medication-induced presentation as a
primary mental disorder that is not caused by substance use and
might prefer allowing 6–8 weeks of abstinence before considering
the diagnosis to be a primary mental disorder. On the other hand,
clinicians who work primarily in psychiatric settings may be more
concerned that given the wide use of substances among patients seen
in clinical settings, such a long waiting period is impractical and
might result in an overdiagnosis of Substance-Induced Disorders
and an underdiagnosis of primary mental disorders. Moreover, it
must be recognized that the one-size-fits-all 1-month time frame
applies to a wide variety of substances and medications with very
different pharmacokinetic properties and a wide variety of possible
consequent psychopathologies. Therefore, the time frame must be
applied flexibly, considering the extent, duration, and nature of the
substance/medication use.
Sometimes, it is simply not possible to determine whether there was
a period of time when the psychiatric symptoms occurred outside of
periods of substance/medication use. This may occur in the often-
encountered situation in which the patient is too poor a historian to
allow a careful determination of past temporal relationships. In
addition, substance use and psychiatric symptoms can have their
onset around the same time (often in adolescence), and both can be
more or less chronic and continuous. In these situations, it may be
necessary to assess the patient during a current period of abstinence
from substance use or to stop the medication suspected of causing
the psychiatric symptoms. If the psychiatric symptoms persist in the
absence of substance/medication use, then the psychiatric disorder
can be considered to be primary. If the symptoms remit during
periods of abstinence, then the substance use is probably primary. It
is important to realize that this judgment can only be made after
waiting for enough time to elapse so as to be confident that the
psychiatric symptoms are not a consequence of withdrawal. Ideally,
the best setting for making this determination is in a facility where
the patient’s access to substances can be controlled and the patient’s
psychiatric symptomatology can be serially assessed. Of course, it is
often impossible to observe a patient for as long as 4 weeks in a
tightly controlled setting. Consequently, these judgments must be
based on less controlled observation, and the clinician’s confidence
in the accuracy of the diagnosis should be more guarded.
o
o
In determining the likelihood that the pattern of
substance/medication use can account for the symptoms, you must
also consider whether the nature, amount, and duration of
substance/medication use are consistent with the development of
the observed psychiatric symptoms. Only certain substances and
medications are known to be causally related to particular
psychiatric symptoms. Moreover, the amount of substance or
medication taken and the duration of its use must be above a certain
threshold for it to reasonably be considered the cause of the
psychiatric symptomatology. For example, a severe and persisting
depressed mood following the isolated use of a small amount of
cocaine should probably not be considered to be attributed to the
cocaine use, even though depressed mood is sometimes associated
with Cocaine Withdrawal. Similarly, cannabis smoked in typical
moderate doses rarely causes prominent psychotic symptoms. For
individuals who are regular substance users, a significant change in
the amount used (either a large increase or a decrease in amount
sufficient to trigger withdrawal symptoms) may in some cases cause
the development of psychiatric symptoms.
You should also consider other factors in the presentation that
suggest that the presentation is not caused by a substance or
medication. These include a history of many similar episodes not
related to substance/medication use, a strong family history of the
particular primary disorder, or the presence of physical examination
or laboratory findings suggesting that a medical condition might be
involved. Considering factors other than substance/medication use
as a cause for the presentation of psychiatric symptoms requires fine
clinical judgment (and often waiting and seeing) to weigh the relative
probabilities in these situations. For example, an individual may
have heavy family loading for Anxiety Disorders and still have a
cocaine-induced panic attack that does not necessarily presage the
development of primary Panic Disorder.
2. In some cases, the substance use can be the consequence or an
associated feature (rather than the cause) of psychiatric
symptomatology. Not uncommonly, the substance-taking behavior can
be considered a form of self-medication for the psychiatric condition. For
example, an individual with a primary Anxiety Disorder might use alcohol
excessively for its sedative and antianxiety effects. One interesting
implication of using a substance to self-medicate is that individuals with
particular psychiatric disorders often preferentially choose certain classes
of substances. For example, patients with negative symptoms of
Schizophrenia often prefer stimulants, whereas patients with Anxiety
Disorders often prefer CNS depressants. The hallmark of a primary
psychiatric disorder with secondary substance use is that the primary
psychiatric disorder occurs first and/or exists at times during the person’s
lifetime when he or she is not using any substance. In the most classic
situation, the period of comorbid psychiatric symptomatology and
substance use is immediately preceded by a period of time when the person
had the psychiatric symptomatology but was abstinent from the substance.
For example, an individual currently with 5 months of heavy alcohol use
and depressive symptomatology might report that the alcohol use started
in the midst of a Major Depressive Episode, perhaps as a way of
counteracting insomnia. Clearly the validity of this judgment depends on
the accuracy of the patient’s retrospective reporting. Because such
information is sometimes suspect, it may be useful to confer with other
informants (e.g., family members) or review past records to document the
presence of psychiatric symptoms occurring in the absence of substance
use.
3. In other cases, both the psychiatric disorder and the substance
use can be initially unrelated and relatively independent of each
other. The high prevalence rates of both psychiatric disorders and
Substance Use Disorders mean that by chance alone, some patients would
be expected to have two apparently independent illnesses (although there
may be some common underlying factor predisposing to the development
of both the Substance Use Disorder and the psychiatric disorder). Of
course, even if initially independent, the two disorders may interact to
exacerbate each other and complicate the overall treatment. This
independent relationship is essentially a diagnosis made by exclusion.
When confronted with a patient having both psychiatric symptomatology
and substance use, you should first rule out that one is causing the other. A
lack of a causal relationship in either direction is more likely if there are
periods when the psychiatric symptoms occur in the absence of substance
use and if the substance use occurs at times unrelated to the psychiatric
symptomatology.
After deciding that a presentation is due to the direct effects of a
substance or medication, you must then determine which DSM-5
Substance-Induced Disorder best describes the presentation. DSM-5
includes a number of specific Substance/Medication-Induced Mental Disorders,
along with Substance Intoxication and Substance Withdrawal. Please refer
to Decision Tree for Excessive Substance Use Decision Tree for Excessive
Substance Use in Chapter 2, “Differential Diagnosis by the Trees,” for a
presentation of the steps involved in making this determination.
Step 3: Rule Out a Disorder Due to a General Medical
Condition
After ruling out a substance/medication-induced etiology, the next step is to
determine whether the psychiatric symptoms are due to the direct effects of a
general medical condition. This and the previous step of the differential diagnosis
make up what was traditionally considered the “organic rule-outs” in psychiatry,
in which the clinician is asked to first consider and rule out “physical” causes of
the psychiatric symptomatology. Although DSM no longer uses words such
as organic, physical, and functional, to avoid the anachronistic mind-body
dualism implicit in such terms, the need to first rule out substances and general
medical conditions as specific causes of the psychiatric symptomatology remains
crucial. For similar reasons, the phrase “due to a medical condition” is avoided in
DSM because of the potential implication that psychiatric symptomatology and
mental disorders are separate and distinct from the concept of “medical
conditions.” In fact, from a disease classification perspective, psychiatric
disorders are but one chapter of the International Classification of Diseases
(ICD), as are infectious diseases, neurological conditions, and so forth. When the
phrase “due to a medical condition” is used, what is really meant is that the
symptoms are due to a medical condition that is classified outside the ICD mental
disorders chapter—that is, a nonpsychiatric medical condition. In DSM-5 and this
handbook, therefore, the phrase “medical condition” is modified with adjectives
such as another, other, or general to clarify that the etiological condition, like a
mental disorder, is a medical condition but that it is differentiated from
psychiatric medical conditions by virtue of being nonpsychiatric.
From a differential diagnostic perspective, ruling out a general medical etiology is
one of the most important and difficult distinctions in psychiatric diagnosis. It is
important because many individuals with general medical conditions have
resulting psychiatric symptoms as a complication of the general medical
condition and because many individuals with psychiatric symptoms have an
underlying general medical condition. The treatment implications of this
differential diagnostic step are also profound. Appropriate identification and
treatment of the underlying general medical condition can be crucial in both
avoiding medical complications and reducing the psychiatric symptomatology.
This differential diagnosis can be difficult for four reasons: 1)
symptoms of some psychiatric disorders and of many general medical conditions
can be identical (e.g., symptoms of weight loss and fatigue can be attributable to a
Depressive or Anxiety Disorder or to a general medical condition); 2) sometimes
the first presenting symptoms of a general medical condition are psychiatric (e.g.,
depression preceding other symptoms in pancreatic cancer or a brain tumor); 3)
the relationship between the general medical condition and the psychiatric
symptoms may be complicated (e.g., depression or anxiety as a psychological
reaction to having the general medical condition vs. the medical condition being a
cause of the depression or anxiety via its direct physiological effect on the CNS);
and 4) patients are often seen in settings primarily geared for the identification
and treatment of mental disorders in which there may be a lower expectation for,
and familiarity with, the diagnosis of medical conditions.
Virtually any psychiatric presentation can be caused by the direct
physiological effects of a general medical condition, and these are
diagnosed in DSM-5 as one of the Mental Disorders Due to Another
Medical Condition (e.g., Depressive Disorder Due to
Hypothyroidism). It is no great trick to suspect the possible etiological role of
a general medical condition if the patient is encountered in a general hospital or
primary care outpatient setting. The real diagnostic challenge occurs in mental
health settings in which the base rate of general medical conditions is much lower
but nonetheless consequential. It is not feasible (nor cost-effective) to order every
conceivable screening test on every patient. You should direct the history,
physical examination, and laboratory tests toward the diagnosis of those general
medical conditions that are most commonly encountered and most likely to
account for the presenting psychiatric symptoms (e.g., thyroid function tests for
depression, brain imaging for late-onset psychotic symptoms).
Once a general medical condition is established, the next task is to
determine its etiological relationship, if any, to the psychiatric
symptoms. There are five possible relationships: 1) the general medical
condition causes the psychiatric symptoms through a direct physiological effect
on the brain; 2) the general medical condition causes the psychiatric symptoms
through a psychological mechanism (e.g., depressive symptoms in response to
being diagnosed with cancer—diagnosed as Major Depressive Disorder or
Adjustment Disorder); 3) medication taken for the general medical condition
causes the psychiatric symptoms, in which case the diagnosis is a MedicationInduced Mental Disorder (see “Step 2: Rule Out Substance Etiology” in this
chapter); 4) the psychiatric symptoms cause or adversely affect the general
medical condition (e.g., in which case Psychological Factors Affecting Other
Medical Condition may be indicated); and 5) the psychiatric symptoms and the
general medical condition are coincidental (e.g., hypertension and
Schizophrenia). In the real clinical world, however, several of these relationships
may occur simultaneously with a multifactorial etiology (e.g., a patient treated
with an antihypertensive medication who has a stroke may develop depression
due to a combination of the direct effects of the stroke on the brain, the
psychological reaction to the resultant paralysis, and a side effect of the
antihypertensive medication).
There are two clues suggesting that psychopathology is caused by the
direct physiological effect of a general medical
condition. Unfortunately, neither of these is infallible, and clinical judgment is
always necessary.
•
•
The first clue involves the nature of the temporal relationship and
requires consideration of whether the psychiatric symptoms begin
following the onset of the general medical condition, vary in severity with
the severity of the general medical condition, and disappear when the
general medical condition resolves. When all of these relationships can be
demonstrated, a fairly compelling case can be made that the general
medical condition has caused the psychiatric symptoms; however, such a
clue does not establish that the relationship is physiological (the temporal
covariation could also be due to a psychological reaction to the general
medical condition). Also, sometimes the temporal relationship is not a
good indicator of underlying etiology. For instance, psychiatric symptoms
may be the first harbinger of the general medical condition and may
precede by months or years any other manifestations. Conversely,
psychiatric symptoms may be a relatively late manifestation occurring
months or years after the general medical condition has been well
established (e.g., depression in Parkinson’s disease).
The second clue that a general medical condition should be considered in
the differential diagnosis is if the psychiatric presentation is atypical in
symptom pattern, age at onset, or course. For example, the presentation
cries out for a medical workup when severe memory or weight loss
accompanies a relatively mild depression or when severe disorientation
accompanies psychotic symptoms. Similarly, the first onset of a manic
episode in an elderly patient may suggest that a general medical condition
is involved in the etiology. However, atypicality does not in and of itself
indicate a general medical etiology because the heterogeneity of primary
psychiatric disorders leads to many “atypical” presentations.
Nonetheless, the most important bottom line with regard to this task in the
differential diagnosis is not to miss possibly important underlying general
medical conditions. Establishing the nature of the causal relationship often
requires careful evaluation, longitudinal follow-up, and trials of treatment.
Finally, if you have determined that a general medical condition is
responsible for the psychiatric symptoms, you must determine which
of the DSM-5 Mental Disorders Due to Another Medical Condition
best describes the presentation. DSM-5 includes a number of such
disorders, each differentiated by the predominant symptom presentation. Please
refer to 2.29 Decision Tree for Etiological Medical Conditions in Chapter 2,
“Differential Diagnosis by the Trees,” for a presentation of the steps involved in
making this determination.
Step 4: Determine the Specific Primary Disorder(s)
Once substance use and general medical conditions have been ruled out as
etiologies, the next step is to determine which among the primary DSM-5 mental
disorders best accounts for the presenting symptomatology. Many of the
diagnostic groupings in DSM-5 (e.g., Schizophrenia Spectrum and Other
Psychotic Disorders, Anxiety Disorders, Dissociative Disorders) are organized
around common presenting symptoms precisely to facilitate this differential
diagnosis. The decision trees in Chapter 2 provide the decision points needed for
choosing among the primary mental disorders that might account for each
presenting symptom. Once you have selected what appears to be the most likely
disorder, you may wish to review the pertinent differential diagnosis table in
Chapter 3, “Differential Diagnosis by the Tables,” to ensure that all other likely
contenders in the differential diagnosis have been considered and ruled out.
Step 5: Differentiate Adjustment Disorders From the
Residual Other Specified or Unspecified Disorders
Many clinical presentations (particularly in outpatient and primary care settings)
do not conform to the particular symptom patterns, or they fall below the
established severity or duration thresholds to qualify for one of the specific DSM5 diagnoses. In such situations, if the symptomatic presentation is severe enough
to cause clinically significant impairment or distress and represents a biological
or psychological dysfunction in the individual, a diagnosis of a mental disorder is
still warranted and the differential comes down to either an Adjustment Disorder
or one of the residual Other Specified or Unspecified categories. If the clinical
judgment is made that the symptoms have developed as a maladaptive response
to a psychosocial stressor, the diagnosis would be an Adjustment Disorder. If it is
judged that a stressor is not responsible for the development of the clinically
significant symptoms, then the relevant Other Specified or Unspecified category
may be diagnosed, with the choice of the appropriate residual category depending
on which DSM-5 diagnostic grouping best covers the symptomatic presentation.
For example, if the patient’s presentation is characterized by depressive
symptoms that do not meet the criteria for any of the disorders included in the
DSM-5 chapter “Depressive Disorders,” then Other Specified Depressive Disorder
or Unspecified Depressive Disorder is diagnosed (rules regarding which of these
two categories to use are provided in the next paragraph). Because stressful
situations are a daily feature of most people’s lives, the judgment in this step is
centered more on whether a stressor is etiological rather than on whether a
stressor is present.
DSM-5 offers two versions of residual categories: Other Specified Disorder and
Unspecified Disorder. As the names suggest, the differentiation between the two
depends on whether the clinician chooses to specify the reason that the
symptomatic presentation does not meet the criteria for any specific category in
that diagnostic grouping. If the clinician wants to indicate the specific reason, the
name of the disorder (“Other Specified Disorder”) is followed by the reason why
the presentation does not conform to any of the specific disorder definitions. For
example, if a patient has a clinically significant symptomatic presentation
characterized by 4 weeks of depressed mood, most of the day nearly every day,
which is accompanied by only two additional depressive symptoms (e.g.,
insomnia and fatigue), the clinician would record Other Specified Depressive
Disorder, Depressive Episode With Insufficient Symptoms. If the clinician
chooses not to indicate the specific reason why the presentation does not conform
to any of the specific disorder definitions, the Unspecified Disorder designation is
used. For example, if the clinician declines to indicate the reason why the
depressive presentation does not fit any of the specified categories, the diagnosis
Unspecified Depressive Disorder is made instead. The clinician might choose the
unspecified option if there is insufficient information to make a more specific
diagnosis and the clinician expects that additional information may be
forthcoming, or if the clinician decides it is in the patient’s best interest not to be
specific about the reason (e.g., to avoid offering potentially stigmatizing
information about the patient).
Step 6: Establish the Boundary With No Mental
Disorder
Generally, the last step in each of the decision trees is to establish the boundary
between a disorder and no mental disorder. This decision is by no means the least
important or easiest to make. Taken individually, many of the symptoms
included in DSM-5 are fairly ubiquitous and are not by themselves indicative of
the presence of a mental disorder. During the course of their lives, most people
may experience periods of anxiety, depression, sleeplessness, or sexual
dysfunction that may be considered as no more than an expected part of the
human condition. To be explicit that not every such individual qualifies for a
diagnosis of a mental disorder, DSM-5 includes with most criteria sets a criterion
that is usually worded more or less as follows: “The disturbance causes clinically
significant distress or impairment in social, occupational, or other important
areas of functioning.” This criterion requires that any psychopathology must lead
to clinically significant problems in order to warrant a mental disorder diagnosis.
For example, a diagnosis of Male Hypoactive Sexual Desire Disorder, which
includes the requirement that the low sexual desire causes clinically significant
distress in the individual, would not be made in a man with low sexual desire who
is not currently in a relationship and who is not particularly bothered by the low
desire.
Unfortunately, but necessarily, DSM-5 makes no attempt to define the
term clinically significant. The boundary between disorder and normality can be
set only by clinical judgment and not by any hard-and-fast rules. What may seem
clinically significant is undoubtedly influenced by the cultural context, the setting
in which the individual is seen, clinician bias, patient bias, and the availability of
resources. “Minor” depression may seem much more clinically significant in a
primary care setting than in a psychiatric emergency room or state hospital
where the emphasis is on the identification and treatment of far more impairing
conditions.
In clinical mental health settings, the judgment regarding whether a presentation
is clinically significant is often a nonissue; the fact that the individual has sought
help automatically makes it “clinically significant.” More challenging are
situations in which the symptomatic picture is discovered in the course of
treating another mental disorder or a medical condition, which, given the high
comorbidity among mental disorders and between mental disorders and medical
conditions, is not an uncommon occurrence. Generally, as a rule of thumb, if the
comorbid psychiatric presentation warrants clinical attention and treatment, it is
considered to be clinically significant.
Finally, some conditions that can impair functioning, such as Uncomplicated
Bereavement, may still not qualify for the use of an Other Specified or
Unspecified Disorder category because they do not represent an internal
psychological or biological dysfunction in the individual, as is required in the
DSM-5 definition of a mental disorder. Such “normal” but impairing
symptomatic presentations may be worthy of clinical attention, but they do not
qualify as a mental disorder and should be diagnosed with a category (usually a V
or Z code, corresponding to ICD-9-CM or ICD-10-CM, respectively) from the
DSM-5 Section II chapter “Other Conditions That May Be a Focus of Clinical
Attention,” which is included after the mental disorders chapters.
Differential Diagnosis and Comorbidity
Differential diagnosis is generally based on the notion that the clinician is
choosing a single diagnosis from among a group of competing, mutually exclusive
diagnoses to best explain a given symptom presentation. For example, in a
patient who presents with delusions, hallucinations, and manic symptoms, the
question is whether the best diagnosis is Schizophrenia, Schizoaffective Disorder,
or Bipolar Disorder With Psychotic Features; only one of these can be given to
describe the current presentation. Very often, however, DSM-5 diagnoses are not
mutually exclusive, and the assignment of more than one DSM-5 diagnosis to a
given patient is both allowed and necessary to adequately describe the presenting
symptoms. Thus, multiple decision trees may need to be consulted to adequately
cover all of the important clinically significant aspects of the patient’s
presentation. For example, a patient who presents with multiple unexpected
panic attacks, significant depression, binge eating, and excessive substance use
would require a consideration of the following decision trees: panic attacks
(Decision Tree for Panic Attacks), depressed mood (Decision Tree for Depressed
Mood), appetite changes or unusual eating behavior (Decision Tree for Appetite
Changes or Unusual Eating Behavior), and excessive substance use (Decision
Tree for Excessive Substance Use). Moreover, because of comorbidity within
diagnostic groupings, multiple passes through a particular decision tree may be
required to cover all possible diagnoses. For example, it is well recognized that if
a patient has one Anxiety Disorder (e.g., Social Anxiety Disorder [Social Phobia]),
he or she is more likely to have other comorbid Anxiety Disorders (e.g.,
Separation Anxiety Disorder, Panic Disorder). The anxiety decision tree (Decision
Tree for Anxiety), however, helps to differentiate among the various Anxiety
Disorders, and therefore a pass through the tree will result in the diagnosis of
only one of the Anxiety Disorders. Multiple passes through the anxiety tree,
answering the key questions differently each time depending on which anxiety
symptom is the current focus, are needed to capture the comorbidity.
The use of multiple diagnoses is in itself neither good nor bad as long as the
implications are understood. A naïve and mistaken view of comorbidity might
assume that a patient assigned more than one descriptive diagnosis actually has
multiple independent conditions. This is certainly not the only possible
relationship. In fact, there are six different ways in which two so-called comorbid
conditions may be related to one another: 1) condition A may cause or predispose
to condition B; 2) condition B may cause or predispose to condition A; 3) an
underlying condition C may cause or predispose to both conditions A and B; 4)
conditions A and B may, in fact, be part of a more complex unified syndrome that
has been artificially split in the diagnostic system; 5) the relationship between
conditions A and B may be artifactually enhanced by definitional overlap; and 6)
the comorbidity is the result of a chance co-occurrence that may be particularly
likely for those conditions that have high base rates. The particular nature of the
relationships is often very difficult to determine. The major point to keep in mind
is that “having” more than one DSM-5 diagnosis does not mean that there is
more than one underlying pathophysiological process. Instead, DSM-5 diagnoses
should be considered descriptive building blocks that are useful for
communicating diagnostic information.
How to Use the Handbook: Case Example
To demonstrate how to use the diagnostic tools provided in this handbook to
determine a differential diagnosis, consider the following case, adapted
from DSM-5 Clinical Cases, edited by John W. Barnhill, M.D. (pp. 32–34).
Adapted with permission from Heckers S: “Sad and Psychotic,” in DSM-5 Clinical
Cases. Edited by Barnhill JW. Washington, DC, American Psychiatric Publishing,
2014, pp. 32–34. Copyright © 2014 American Psychiatric Association.
John is a 25-year-old single, unemployed white man who has been seeing a
psychiatrist for several years for management of psychosis, depression, anxiety,
and abuse of marijuana and alcohol.
After an apparently normal childhood, John began to show dysphoric mood,
anhedonia, low energy, and social isolation by age 15. At about the same time,
John began to drink alcohol and smoke marijuana every day. In addition, he
developed recurrent panic attacks, marked by a sudden onset of palpitations,
diaphoresis, and thoughts that he was going to die. When he was at his most
depressed and panicky, he twice received a combination of sertraline 100 mg/day
and psychotherapy. In both cases, his most intense depressive symptoms lifted
within a few weeks, and he discontinued the sertraline after a few months.
Between episodes of severe depression, he was generally seen as sad, irritable,
and amotivated. His school performance declined around tenth grade and
remained marginal through the rest of high school. He did not attend college,
which had been his parents’ expectation, but instead lived at home and did odd
jobs in the neighborhood.
Around age 20, John developed a psychotic episode in which he had the
conviction that he had murdered people when he was 6 years old. Although he
could not remember who these people were or the circumstances, he was
absolutely convinced that it had happened, something that was confirmed by
continuous voices accusing him of being a murderer. He also became convinced
that other people would punish him for what happened when he was 6 years old
and thus he also feared for his life. Over the next 2 or 3 weeks, he became guilt
ridden and preoccupied with the idea that he should kill himself by slashing his
wrists, culminating in his being psychiatrically hospitalized because of his
parents’ concerns that he would act on these delusions. Although his affect on
admission was anxious, within a couple of days he also became very depressed
with accompanying symptoms of dysphoria, prominent anhedonia, poor sleep,
and decreased appetite and concentration. With the combined use of
antipsychotic and antidepressant medications, both the depression and psychotic
symptoms remitted after an additional 4 weeks. Thus, the total duration of the
psychotic episode was approximately 7 weeks, 4 of which were also characterized
by the depressive episode. He was hospitalized with the same pattern of
symptoms two additional times before age 22, starting out with a couple of weeks
of delusions and hallucinations related to his conviction that he had murdered
someone when he was a child, followed by severe depression lasting an additional
month. Both of those relapses occurred while he was apparently adhering to
reasonable dosages of antipsychotic medication. For the past 3 years, John has
been adherent to clozapine and has been without any further episodes of
hallucinations, delusions, or depression.
John began to abuse marijuana and alcohol at age 15. Before the onset of
psychosis at age 20, he smoked several joints of marijuana almost daily and binge
drank on weekends with occasional blackouts. After the onset of psychosis, his
marijuana use decreased significantly, yet he continued to have two more
psychotic episodes through age 22 (as described above). He started attending
Alcoholics Anonymous and Narcotics Anonymous groups, achieved sobriety from
marijuana and alcohol at age 23, and has since remained sober.
This case presents with both prominent psychotic symptoms (delusions and
hallucinations) and mood symptoms (depression). Thus, the clinician can start
the differential diagnosis process with any of the following decision trees:
delusions (Decision Tree for Delusions), hallucinations (Decision Tree for
Hallucinations), or depressed mood (Decision Tree for Depressed Mood). Given
the especially prominent nature of the delusions, we first start with the delusions
decision tree (Decision Tree for Delusions). The first question, whether the
beliefs are a manifestation of a culturally or religiously sanctioned belief system,
can be answered “no” because John’s fixed belief that he murdered people when
he was age 6 is not a manifestation of any sanctioned belief system and is thus
appropriately considered to be a delusion. The next question, regarding whether
his delusions are due to the physiological effects of a substance, must be seriously
considered given the fact that his delusions first emerged at age 20 during a time
when he was smoking several joints of marijuana almost daily. To answer this
question, we need to consider Step 2 of the six differential diagnosis steps
presented earlier in this chapter, which provides guidance on how to rule out a
substance etiology. In determining whether there is a causal relationship between
the marijuana use and the delusions, we need to determine whether all three of
the following conditions are true: 1) that there is a close temporal relationship
between marijuana use and the onset and maintenance of the delusions, 2) that
the pattern of marijuana use is consistent (in terms of dosage and duration) with
the development of delusions, and 3) that there is no alternative (i.e., nonsubstance/medication-induced) explanation for the delusions. Although it is not
common for marijuana to cause florid delusions, heavy marijuana use in some
vulnerable individuals can result in delusions during Marijuana Intoxication, so
the second condition (i.e., substance use is heavy and/or prolonged enough to
induce the symptom) is met. In evaluating the first condition, however, although
the delusions emerged during heavy marijuana use, the fact that the delusions
persisted in the hospital when John was abstinent from marijuana and then
subsequently reoccurred when his marijuana use was minimal indicates that the
delusions cannot be explained as a manifestation of his marijuana use. Thus, the
answer to the second question in the delusions decision tree, regarding whether
there is a cannabis etiology for the delusions, is “no.” The absence of any reported
general medical conditions in John also rules out a medical etiology, and
therefore the answer to the following question is also “no.”
After ruling out cultural and religious, substance/medication-induced, and
general medical etiologies for John’s delusions, we then must differentiate among
the primary psychotic and mood disorders as possible explanations for the
delusions. The next question, which asks whether the delusions have occurred
only in the context of an episode of elevated, expansive, or irritable mood, is
answered “no” because of the absence of a history of manic or hypomanic
symptoms. The subsequent question, about whether the delusions have occurred
only in the context of an episode of depressed mood, is also answered “no”
because the delusions also occurred at times when John was not experiencing a
depressive episode (i.e., each psychotic episode is characterized by a several-week
period of delusions before the development of the severe depressive symptoms).
The next block of questions in the delusions tree provides the differential
diagnosis of non-mood-restricted delusions. The question inquiring whether the
delusions last for 1 month or more is answered “yes” (i.e., each time the delusions
have occurred, they lasted for several weeks), moving us for the first time to the
right in the decision tree to consider the differential between Schizophrenia,
Schizophreniform Disorder, Schizoaffective Disorder, Delusional Disorder, and
Bipolar or Major Depressive Disorder With Psychotic Features. The subsequent
question about whether the delusions are accompanied by other psychotic
symptoms characteristic of Schizophrenia (i.e., hallucinations, disorganized
speech, grossly disorganized or catatonic behavior, or negative symptoms) is also
answered “yes” given that in John’s case the delusions of having murdered a
person when he was a child are accompanied by accusatory auditory
hallucinations. The next question (i.e., whether there is a history of Major
Depressive or Manic Episodes) is answered “yes” given the history of recurrent
Major Depressive Episodes, as is the following question (i.e., whether during an
uninterrupted period of illness the psychotic symptoms occur concurrently with
the mood episodes) because the delusions and hallucinations continued to persist
after the Major Depressive Episodes emerged, thus indicating a period of overlap.
The next question, which provides the crucial differential diagnostic distinction
between Schizoaffective Disorder and Schizophrenia, asks whether, during an
uninterrupted period of illness, the mood episodes have been present for
a minority of the total duration of the active and residual phases of the illness. In
John’s case, each of the psychotic episodes was present for approximately 7–8
weeks, with about 4 of those weeks characterized by the simultaneous occurrence
of a severe Major Depressive Episode. Therefore, it is not the case that the mood
episodes were present for only a minority of the time during an uninterrupted
episode of illness (they were in fact present for a majority of the time), so the
question is answered “no,” ruling out the diagnoses of both Schizophrenia and
Schizophreniform Disorder. The next question, regarding whether delusions and
hallucinations have occurred for at least 2 weeks in the absence of a Major
Depressive Episode or Manic Episode, is answered “yes” (i.e., for the first 3 or 4
weeks of the psychotic episode, John was anxious but not suffering from
significant depressed mood), bringing us to the terminal branch of the delusions
decision tree (Decision Tree for Delusions) and the diagnosis of Schizoaffective
Disorder. It should be noted that given the complete co-occurrence of the
delusions and hallucinations during the psychotic episodes, had we started with
the hallucinations tree (Decision Tree for Hallucinations) instead of the delusions
tree, we would have gone through almost the exact same sequence of steps to
arrive at the diagnosis of Schizoaffective Disorder, given the similarity of the
branching structure of the delusions and hallucinations trees.
Alternatively, we could have approached this case from the perspective of John’s
severe depressive symptoms and instead started with the depressed mood
decision tree (Decision Tree for Depressed Mood). The first question in this tree
inquires about a substance etiology for the depressive symptoms. Applying the
same principles discussed above with regard to the relationship between John’s
marijuana use and his delusions, this question can also be answered in the
negative because although the marijuana use is sufficient to cause depressed
mood, the fact that John continued to experience episodes of severe depression
after he stopped his heavy use of marijuana indicates that, like the delusions, his
depression cannot be considered to have been induced by the marijuana use. The
next question asks whether the depression is due to the physiological effects of a
general medical condition, and that question can also be answered “no” because
of the absence of any history of medical problems. The next question asks
whether the depressed mood was part of a Major Depressive Episode. The answer
to that question is “yes” given that the depressive periods that developed after the
onset of delusions and hallucinations were characterized by approximately 4
weeks of dysphoric mood, prominent anhedonia, poor sleep, decreased appetite,
and reduced concentration, thus meeting syndromal criteria for a Major
Depressive Episode. Note that the decision tree does not end at this point but that
the diagnostic flow continues onward because Major Depressive Episode is not a
codable diagnostic entity in DSM-5 but instead comprises one of the building
blocks for the diagnoses of Bipolar I or Bipolar II Disorder, Major Depressive
Disorder, and Schizoaffective Disorder. The next question, about the presence of
clinically significant manic or hypomanic symptoms, is answered “no,” bringing
us to a consideration of the relationship between the Major Depressive Episodes
and the psychotic symptoms. The question about whether there is a history of
delusions or hallucinations is answered “yes,” bringing us to the critical question
as to whether the psychotic symptoms occur exclusively during Manic or Major
Depressive Episodes. In John’s case, the psychotic symptoms have not occurred
exclusively during the Major Depressive Episodes (i.e., the delusions and
hallucinations occurred on their own for 3–4 weeks prior to the onset of the
depressive episode), so the answer to this question is “no.” At this point in the
depressed mood decision tree (Decision Tree for Depressed Mood), rather than
being offered additional questions, we are told that a Schizophrenia Spectrum or
Other Psychotic Disorder is present and are instructed to go to the delusions tree
(Decision Tree for Delusions) or hallucinations tree (Decision Tree for
Hallucinations) for the differential diagnosis, resulting in the diagnosis of
Schizoaffective Disorder.
After arriving at the diagnosis of Schizoaffective Disorder through the use of the
decision trees, we can refer to the DSM-5 classification in the Appendix to get the
diagnostic code for Schizoaffective Disorder and/or we can review the differential
diagnosis table for Schizoaffective Disorder in Chapter 3 (Table 3.2.2) to confirm
that the key contenders to a diagnosis of Schizoaffective Disorder have been
appropriately ruled out. The two main diagnostic contenders in this case are
Schizophrenia and Major Depressive Disorder With Psychotic Features.
Accordingly, the differential diagnosis table for Schizoaffective Disorder notes
that Schizophrenia is differentiated from Schizoaffective Disorder by virtue of the
fact that Schizophrenia is characterized by mood episodes that “have been
present for a minority of the total duration of the active and residual periods of
the illness.” In John’s case, each episode of the illness was characterized by a
Major Depressive Episode being present for more than half of the time (i.e.,
about 4 weeks) of the total duration (i.e., 7–8 weeks), thus ruling out the
diagnosis of Schizophrenia. Moreover, the table also notes that Schizoaffective
Disorder is differentiated from Major Depressive Disorder With Psychotic
Features by virtue of the fact that Major Depressive Disorder With Psychotic
Features is characterized by psychotic symptoms that occur exclusively during
Major Depressive Episodes. In John’s case, the psychotic symptoms were not
confined exclusively to the depressive episodes, ruling out the diagnosis of Major
Depressive Disorder With Psychotic Features.
DSM-5 Diagnoses and New ICD-10-CM Codes
As Ordered in the DSM-5 Classification
DSM-5 Recommended ICD-10-CM
Code for use through September 30,
2018*
DSM-5 Recommended ICD-10-CM
Code for use beginning October 1,
2018*
Factitious Disorder Imposed on Another
F68.10
F68.A
Cannabis Withdrawal, With moderate or severe use disorder
F12.288
F12.23
Cannabis Withdrawal, Without use disorder
Not in DSM-5
F12.93
Opioid Withdrawal, Without use disorder
Not in DSM-5
F11.93
Sedative, Hypnotic, or Anxiolytic Withdrawal,
Without perceptual disturbances, Without use disorder
Not in DSM-5
F13.939
Sedative, Hypnotic, or Anxiolytic Withdrawal,
With perceptual disturbances, Without use disorder
Not in DSM-5
F13.932
Amphetamine or Other Stimulant Withdrawal,
Without use disorder
Not in DSM-5
F15.93
Other (or Unknown) Substance Withdrawal, Without use disorder
Not in DSM-5
F19.939
Sedative, Hypnotic, or Anxiolytic Withdrawal Delirium,
Without use disorder
Not in DSM-5
F13.931
No Diagnosis or Condition*
Not in DSM-5*
Z03.89*
DSM-5 Recommended ICD-10-CM
Code for use through September 30,
2018*
DSM-5 Recommended ICD-10-CM
Code for use beginning October 1,
2018*
Not in DSM-5
F11.93
F12.288
F12.23
Cannabis Withdrawal, Without use disorder
Not in DSM-5
F12.93
Sedative, Hypnotic, or Anxiolytic Withdrawal Delirium,
Without use disorder
Not in DSM-5
F13.931
Sedative, Hypnotic, or Anxiolytic Withdrawal,
With perceptual disturbances, Without use disorder
Not in DSM-5
F13.932
Sedative, Hypnotic, or Anxiolytic Withdrawal,
Without perceptual disturbances, Without use disorder
Not in DSM-5
F13.939
Amphetamine or Other Stimulant Withdrawal,
Without use disorder
Not in DSM-5
F15.93
Other (or Unknown) Substance Withdrawal, Without use disorder
Not in DSM-5
F19.939
F68.10
F68.A
Not in DSM-5*
Z03.89*
Disorder*
As Ordered in the ICD-10-CM Classification
Disorder*
Opioid Withdrawal, Without use disorder
Cannabis Withdrawal, With moderate or severe use disorder
Factitious Disorder Imposed on Another
No Diagnosis or Condition*
*Note: Prior to May 2018, a "no diagnosis or condition" category had been omitted in DSM-5. The DSM-5 Steering Committee subsequently approved the inclusion
of this category, and its corresponding ICD-10-CM code, Z03.89 "No diagnosis or condition," is available for immediate use.
The Case of Bogdan
Bogdan is a 12-year-old male in 7th grade who was brought in for services by his
adoptive mother. He is very small in stature, appearing to be only 8 years old. He also
acts younger than his 12 years, carrying around toy cars in his pockets, which he
proudly displays and talks about in detail.
Bogdan was adopted at age 3½ from an orphanage in Russia. The orphanage knows
little about early developmental milestones, but Russian staff noted that Bogdan’s
language was far less developed than that of his peers at the time of his adoption.
The mother stated that Bogdan came to the United States not knowing any English. She
knows very little about his family of origin other than that he lived with his biological
parents until age 2 and then lived in the orphanage until he was adopted. She reported
that the plane ride from Russia was horrible and that Bogdan cried the entire flight and
refused to sleep for the first 2 days they had him. They tried holding him, but he would
not quiet.
The adoptive parents are upper middle class and have three biological children (ages 9,
7, and 5). Bogdan is reported to often get upset with his siblings and hit or kick them.
His mother stated that Bogdan has always had issues with jealousy, and when her other
children were younger, she had to closely monitor him when he was around them. She
reported several occasions when she found Bogdan attempting to suffocate each of his
younger siblings when they were babies. Bogdan’s mother explained this as part of his
“always being immature” and not good at explaining himself. Besides this, his mother
reported that he is not a “mean” child but tends to function according to his own rules.
He often needed reminders to use his “indoor voice” and to “wait his turn to speak.”
The mother reported that Bogdan often hides food in his room and gorges himself when
he eats. She said she does not understand this behavior because he always has
enough food, and she never restricts his eating. In fact, because of his small size and
weight, she often encourages him to eat more. She also reported that Bogdan hates
any type of transition and will get upset and have temper tantrums if she does not
prepare him for any changes in plans. He is reported to kick and hit both parents, and
they have had to restrain him at times to stop him from hurting himself and others. He
sometimes reacted when his lunch was packed differently within his lunch box for
school. He also seemed to pay less attention to teachers and often interrupted class
with his own comments.
Initially Bogdan’s parents were unsure what to do about their son’s behaviors. His
mother is the primary caretaker and his father thought she should handle any therapy or
problems related to school. His mother reported that she was now “at the end of her
rope” and was ready to give her son up to foster care. Both parents are exhausted.
Bogdan’s mother shared her frustration with Bogdan’s father, who “just does not
understand how hard it is to care for him.”
The parents have never sought help before, as Bogdan managed to largely keep up
with his schoolwork. His mother said that he has always taken things literally, but up
until 6th grade, he had attended school without major problems. They had not been
concerned about his grades or lack of friends. His mother said that he has always been
“very shy” and never had a “best friend.” He has always shown interest in cars, trains,
and trucks. Recently, behaviors at school changed and worsened. His school has
complained of his inability to focus and the increase in his disruptive behaviors.
Collateral contact with his teachers confirmed that he struggles with school, has no
friends, and often has “meltdowns” when he does not get his way. One teacher noted
that in small group classroom activities, Bogdan has trouble with restlessness and will
stumble over his words, pause excessively, and restart talking fairly rapidly and loudly.
In 6th grade his teachers were concerned about occasional facial “tics” that occurred at
times.
Prior to meeting with the school social worker today, Bogdan had never had any testing
for special education, nor had he ever received any counseling services. During this
intake, the school social worker met briefly with Bogdan alone.
During this time, he was clearly restless, appeared anxious, and avoided her in the
room. He was very slow to engage with her and was distracted by his pocket toys,
which he fingered. He had pressured speech and some facial tics and was unable to
keep his legs still during the interview. When he did engage, he chose to play a board
game during his time in the session and he talked in detail about World War II and each
of the boats in the game. His hand was in his pocket fingering toys at some moments.
When asked how he knew so much about all the warships, he stated that he often
watched television documentaries on the subject. Once on this topic he took less time to
respond and spoke at length. His teachers commented that he talks more about this
topic at other times at school. Bogdan appeared oriented to time and place. Voice in this
interview was somewhat monotonic and repetitive of his interests. He was generally
cooperative, and the interview passed without incident although it was obvious that he
was eager to be “dismissed” from the meeting.
Adapted from: Plummer, S.-B., Makris, S., & Brocksen, S. (2013). Social work case
studies: Concentration year. Baltimore, MD: Laureate Publishing.
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