Mood Disorders by Anda Gershon and Renee Thompson is licensed under a Creative Commons AttributionNonCommercial-ShareAlike 4.0 International license. © 2015, Diener Education Fund.
By Anda Gershon and Renee Thompson
Stanford University, Washington University in St. Louis
Everyone feels down or euphoric from time to time, but this is different from having a mood disorder
such as major depressive disorder or bipolar disorder. Mood disorders are extended periods of depressed,
euphoric, or irritable moods that in combination with other symptoms cause the person significant
distress and interfere with his or her daily life, often resulting in social and occupational difficulties. In
this module, we describe major mood disorders, including their symptom presentations, general
prevalence rates, and how and why the rates of these disorders tend to vary by age, gender, and race. In
addition, biological and environmental risk factors that have been implicated in the development and
course of mood disorders, such as heritability and stressful life events, are reviewed. Finally, we provide
an overview of treatments for mood disorders, covering treatments with demonstrated effectiveness, as
well as new treatment options showing promise.
Describe the diagnostic criteria for mood disorders.
Understand age, gender, and ethnic differences in prevalence rates of mood disorders.
Identify common risk factors for mood disorders.
Know effective treatments of mood disorders.
The actress Brooke Shields published a memoir titled Down Came the Rain: My Journey through
Postpartum Depression in which she described her struggles with depression following the birth of her
daughter. Despite the fact that about one in 20 women experience depression after the birth of a baby
(American Psychiatric Association [APA], 2013), postpartum depression—recently renamed “perinatal
depression”—continues to be veiled by stigma, owing in part to a widely held expectation that
motherhood should be a time of great joy. In an opinion piece in the New York Times, Shields revealed
that entering motherhood was a profoundly overwhelming experience for her. She vividly describes
experiencing a sense of “doom” and “dread” in response to her newborn baby. Because motherhood is
conventionally thought of as a joyous event and not associated with sadness and hopelessness, responding
to a newborn baby in this way can be shocking to the new mother as well as those close to her. It may
also involve a great deal of shame for the mother, making her reluctant to divulge her experience to
others, including her doctors and family.
Feelings of shame are not unique to perinatal depression. Stigma applies to other types of depressive
and bipolar disorders and contributes to people not always receiving the necessary support and
treatment for these disorders. In fact, the World Health Organization ranks both major depressive
disorder (MDD) and bipolar disorder (BD) among the top 10 leading causes of disability worldwide.
Further, MDD and BD carry a high risk of suicide. It is estimated that 25%–50% of people diagnosed with
BD will attempt suicide at least once in their lifetimes (Goodwin & Jamison, 2007).
What Are Mood Disorders?
Everyone experiences brief periods of sadness, irritability, or euphoria. This is different than having a mood
disorder, such as MDD or BD, which are characterized by a constellation of symptoms that causes people
significant distress or impairs their everyday functioning.
Major Depressive Episode
A major depressive episode (MDE) refers to symptoms that co-occur for at least two weeks and cause
significant distress or impairment in functioning, such as interfering with work, school, or relationships.
Core symptoms include feeling down or depressed or experiencing anhedonia—loss of interest or pleasure
in things that one typically enjoys. According to the fifth edition of the Diagnostic and Statistical Manual
(DSM-5; APA, 2013), the criteria for an MDE require five or more of the following nine symptoms, including
one or both of the first two symptoms, for most of the day, nearly every day:
1. depressed mood
2. diminished interest or pleasure in almost all activities
3. significant weight loss or gain or an increase or decrease in appetite
4. insomnia or hypersomnia
5. psychomotor agitation or retardation
6. fatigue or loss of energy
7. feeling worthless or excessive or inappropriate guilt
8. diminished ability to concentrate or indecisiveness
9. recurrent thoughts of death, suicidal ideation, or a suicide attempt
These symptoms cannot be caused by physiological effects of a substance or a general medical condition
Manic or Hypomanic Episode
The core criterion for a manic or hypomanic episode is a distinct period of abnormally and persistently
euphoric, expansive, or irritable mood and persistently increased goal-directed activity or energy. The
mood disturbance must be present for one week or longer in mania (unless hospitalization is required)
or four days or longer in hypomania. Concurrently, at least three of the following symptoms must be
present in the context of euphoric mood (or at least four in the context of irritable mood):
1. inflated self-esteem or grandiosity
2. increased goal-directed activity or psychomotor agitation
3. reduced need for sleep
4. racing thoughts or flight of ideas
6. increased talkativeness
7. excessive involvement in risky behaviors
Manic episodes are distinguished from hypomanic episodes by their duration and associated impairment;
whereas manic episodes must last one week and are defined by a significant impairment in functioning,
hypomanic episodes are shorter and not necessarily accompanied by impairment in functioning.
Unipolar Mood Disorders
Two major types of unipolar disorders described by the DSM-5 (APA, 2013) are major depressive disorder
and persistent depressive disorder (PDD; dysthymia). MDD is defined by one or more MDEs, but no history
of manic or hypomanic episodes. Criteria for PDD are feeling depressed most of the day for more days
than not, for at least two years. At least two of the following symptoms are also required to meet criteria
1. poor appetite or overeating
2. insomnia or hypersomnia
3. low energy or fatigue
4. low self-esteem
5. poor concentration or difficulty making decisions
6. feelings of hopelessness
Like MDD, these symptoms need to cause significant distress or impairment and cannot be due to the
effects of a substance or a general medical condition. To meet criteria for PDD, a person cannot be without
symptoms for more than two months at a time. PDD has overlapping symptoms with MDD. If someone
meets criteria for an MDE during a PDD episode, the person will receive diagnoses of PDD and MDD.
Bipolar Mood Disorders
Three major types of BDs are described by the DSM-5 (APA, 2013). Bipolar I Disorder (BD I), which was
previously known as manic-depression, is characterized by a single (or recurrent) manic episode. A
depressive episode is not necessary but commonly present for the diagnosis of BD I. Bipolar II Disorder is
characterized by single (or recurrent) hypomanic episodes and depressive episodes. Another type of BD
is cyclothymic disorder, characterized by numerous and alternating periods of hypomania and depression,
lasting at least two years. To qualify for cyclothymic disorder, the periods of depression cannot meet full
diagnostic criteria for an MDE; the person must experience symptoms at least half the time with no more
than two consecutive symptom-free months; and the symptoms must cause significant distress or
Text Box 1: Specifiers
It is important to note that the DSM-5 was published in 2013, and findings based on the updated manual
will be forthcoming. Consequently, the research presented below was largely based on a similar, but not
identical, conceptualization of mood disorders drawn from the DSM-IV(APA, 2000).
How Common Are Mood Disorders? Who Develops Mood Disorders?
In a nationally representative sample, lifetime prevalence rate for MDD is 16.6% (Kessler, Berglund,
Demler, Jin, Merikangas, & Walters, 2005). This means that nearly one in five Americans will meet the
criteria for MDD during their lifetime. The 12-month prevalence—the proportion of people who meet
criteria for a disorder during a 12-month period—for PDD is approximately 0.5% (APA, 2013).
Although the onset of MDD can occur at any time throughout the lifespan, the average age of onset is
mid-20s, with the age of onset decreasing with people born more recently (APA, 2000). Prevalence of
MDD among older adults is much lower than it is for younger cohorts (Kessler, Birnbaum, Bromet, Hwang,
Sampson, & Shahly, 2010). The duration of MDEs varies widely. Recovery begins within three months for
40% of people with MDD and within 12 months for 80% (APA, 2013). MDD tends to be a recurrent disorder
with about 40%–50% of those who experience one MDE experiencing a second MDE (Monroe & Harkness,
2011). An earlier age of onset predicts a worse course. About 5%–10% of people who experience an MDE
will later experience a manic episode (APA, 2000), thus no longer meeting criteria for MDD but instead
meeting them for BD I. Diagnoses of other disorders across the lifetime are common for people with MDD:
59% experience an anxiety disorder; 32% experience an impulse control disorder, and 24% experience a
substance use disorder (Kessler, Merikangas, & Wang, 2007).
Women experience two to three times higher rates of MDD than do men (Nolen-Hoeksema & Hilt, 2009).
This gender difference emerges during puberty (Conley & Rudolph, 2009). Before puberty, boys exhibit
similar or higher prevalence rates of MDD than do girls (Twenge & Nolen-Hoeksema, 2002). MDD is
inversely correlated with socioeconomic status (SES), a person’s economic and social position based on
income, education, and occupation. Higher prevalence rates of MDD are associated with lower SES
(Lorant, Deliege, Eaton, Robert, Philippot, & Ansseau, 2003), particularly for adults over 65 years old
(Kessler et al., 2010). Independent of SES, results from a nationally representative sample found that
European Americans had a higher prevalence rate of MDD than did African Americans and Hispanic
Americans, whose rates were similar (Breslau, Aguilar-Gaxiola, Kendler, Su, Williams, & Kessler, 2006).
The course of MDD for African Americans is often more severe and less often treated than it is for
European Americans, however (Williams et al., 2007). Native Americans have a higher prevalence rate
than do European Americans, African Americans, or Hispanic Americans (Hasin, Goodwin, Stinson &
Grant, 2005). Depression is not limited to industrialized or western cultures; it is found in all countries
that have been examined, although the symptom presentation as well as prevalence rates vary across
cultures (Chentsova-Dutton & Tsai, 2009).
Adolescents experience a higher incidence of bipolar spectrum disorders than do adults. Making matters
worse, those who are diagnosed with BD at a younger ago seem to suffer symptoms more intensely than
those with adult onset.
The lifetime prevalence rate of bipolar spectrum disorders in the general U.S. population is estimated at
approximately 4.4%, with BD I constituting about 1% of this rate (Merikangas et al., 2007). Prevalence
estimates, however, are highly dependent on the diagnostic procedures used (e.g., interviews vs. selfreport) and whether or not sub-threshold forms of the disorder are included in the estimate. BD often
co-occurs with other psychiatric disorders. Approximately 65% of people with BD meet diagnostic criteria
for at least one additional psychiatric disorder, most commonly anxiety disorders and substance use
disorders (McElroy et al., 2001). The co-occurrence of BD with other psychiatric disorders is associated
with poorer illness course, including higher rates of suicidality (Leverich et al., 2003). A recent crossnational study sample of more than 60,000 adults from 11 countries, estimated the worldwide prevalence
of BD at 2.4%, with BD I constituting 0.6% of this rate (Merikangas et al., 2011). In this study, the
prevalence of BD varied somewhat by country. Whereas the United States had the highest lifetime
prevalence (4.4%), India had the lowest (0.1%). Variation in prevalence rates was not necessarily related
to SES, as in the case of Japan, a high-income country with a very low prevalence rate of BD (0.7%).
With regard to ethnicity, data from studies not confounded by SES or inaccuracies in diagnosis are limited,
but available reports suggest rates of BD among European Americans are similar to those found among
African Americans (Blazer et al., 1985) and Hispanic Americans (Breslau, Kendler, Su, Gaxiola-Aguilar, &
Kessler, 2005). Another large community-based study found that although prevalence rates of mood
disorders were similar across ethnic groups, Hispanic Americans and African Americans with a mood
disorder were more likely to remain persistently ill than European Americans (Breslau et al., 2005).
Compared with European Americans with BD, African Americans tend to be underdiagnosed for BD (and
over-diagnosed for schizophrenia) (Kilbourne, Haas, Mulsant, Bauer, & Pincus, 2004; Minsky, Vega,
Miskimen, Gara, & Escobar, 2003), and Hispanic Americans with BD have been shown to receive fewer
psychiatric medication prescriptions and specialty treatment visits (Gonzalez et al., 2007). Misdiagnosis
of BD can result in the underutilization of treatment or the utilization of inappropriate treatment, and
thus profoundly impact the course of illness.
As with MDD, adolescence is known to be a significant risk period for BD; mood symptoms start by
adolescence in roughly half of BD cases (Leverich et al., 2007; Perlis et al., 2004). Longitudinal studies
show that those diagnosed with BD prior to adulthood experience a more pernicious course of illness
relative to those with adult onset, including more episode recurrence, higher rates of suicidality, and
profound social, occupational, and economic repercussions (e.g., Lewinsohn, Seeley, Buckley, & Klein,
2002). The prevalence of BD is substantially lower in older adults compared with younger adults (1% vs.
4%) (Merikangas et al., 2007).
What Are Some of the Factors Implicated in the Development and Course of
Mood disorders are complex disorders resulting from multiple factors. Causal explanations can be
attempted at various levels, including biological and psychosocial levels. Below are several of the key
factors that contribute to onset and course of mood disorders are highlighted.
Research across family and twin studies has provided support that genetic factors are implicated in the
development of MDD. Twin studies suggest that familial influence on MDD is mostly due to genetic effects
and that individual-specific environmental effects (e.g., romantic relationships) play an important role,
too. By contrast, the contribution of shared environmental effect by siblings is negligible (Sullivan, Neale
& Kendler, 2000). The mode of inheritance is not fully understood although no single genetic variation
has been found to increase the risk of MDD significantly. Instead, several genetic variants and
environmental factors most likely contribute to the risk for MDD (Lohoff, 2010).
One environmental stressor that has received much support in relation to MDD is stressful life events. In
particular, severe stressful life events—those that have long-term consequences and involve loss of a
significant relationship (e.g., divorce) or economic stability (e.g., unemployment) are strongly related to
depression (Brown & Harris, 1989; Monroe et al., 2009). Stressful life events are more likely to predict
the first MDE than subsequent episodes (Lewinsohn, Allen, Seeley, & Gotlib, 1999). In contrast, minor
events may play a larger role in subsequent episodes than the initial episodes (Monroe & Harkness,
Depression research has not been limited to examining reactivity to stressful life events. Much research,
particularly brain imagining research using functional magnetic resonance imaging (fMRI), has centered
on examining neural circuitry—the interconnections that allow multiple brain regions to perceive,
generate, and encode information in concert. A meta-analysis of neuroimaging studies showed that
when viewing negative stimuli (e.g., picture of an angry face, picture of a car accident), compared with
healthy control participants, participants with MDD have greater activation in brain regions involved in
stress response and reduced activation of brain regions involved in positively motivated behaviors
(Hamilton, Etkin, Furman, Lemus, Johnson, & Gotlib, 2012).
Other environmental factors related to increased risk for MDD include experiencing early adversity(e.g.,
childhood abuse or neglect; Widom, DuMont, & Czaja, 2007), chronic stress (e.g., poverty) and
interpersonal factors. For example, marital dissatisfaction predicts increases in depressive symptoms in
both men and women. On the other hand, depressive symptoms also predict increases in marital
dissatisfaction (Whisman & Uebelacker, 2009). Research has found that people with MDD generate
some of their interpersonal stress (Hammen, 2005). People with MDD whose relatives or spouses can be
described as critical and emotionally overinvolved have higher relapse rates than do those living with
people who are less critical and emotionally overinvolved (Butzlaff & Hooley, 1998).
People’s attributional styles or their general ways of thinking, interpreting, and recalling information
have also been examined in the etiology of MDD (Gotlib & Joormann, 2010). People with a pessimistic
attributional style tend to make internal (versus external), global (versus specific), and stable (versus
unstable) attributions to negative events, serving as a vulnerability to developing MDD. For example,
someone who when he fails an exam thinks that it was his fault (internal), that he is stupid (global), and
that he will always do poorly (stable) has a pessimistic attribution style. Several influential theories of
depression incorporate attributional styles (Abramson, Metalsky, & Alloy, 1989;Abramson Seligman, &
Although there have been important advances in research on the etiology, course, and treatment of BD,
there remains a need to understand the mechanisms that contribute to episode onset and relapse. There
is compelling evidence for biological causes of BD, which is known to be highly heritable (McGuffin,
Rijsdijk, Andrew, Sham, Katz, & Cardno, 2003). It may be argued that a high rate of heritability
demonstrates that BD is fundamentally a biological phenomenon. However, there is much variability in
the course of BD both within a person across time and across people (Johnson, 2005). The triggers that
determine how and when this genetic vulnerability is expressed are not yet understood; however, there
is evidence to suggest that psychosocial triggers may play an important role in BD risk (e.g., Johnson et
al., 2008; Malkoff-Schwartz et al., 1998).
In addition to the genetic contribution, biological explanations of BD have also focused on brain function.
Many of the studies using fMRI techniques to characterize BD have focused on the processing of emotional
stimuli based on the idea that BD is fundamentally a disorder of emotion (APA, 2000). Findings show
that regions of the brain thought to be involved in emotional processing and regulation are activated
differently in people with BD relative to healthy controls (e.g., Altshuler et al., 2008; Hassel et al., 2008;
Lennox, Jacob, Calder, Lupson, & Bullmore, 2004).
However, there is littl ...
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