LO 6 Summarize the symptoms and causes of major depressive disorder.

During that hospital stay, doctors gave Melissa a new diagnosis in addition to OCD. They told her that she was suffering from depression. Apparently, the profound sadness and helplessness she had been feeling were symptoms of major depressive disorder, one of the depressive disorders described in the DSM–5 (Table 12.5). A major depressive episode is evident if five or more of the symptoms listed below (1) occur for at least 2 consecutive weeks and represent a change from prior functioning, (2) cause significant distress or impairment, and (3) are not due to a medical or drug-related condition:

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Someone with five or more of these symptoms would feel significantly distressed and experience problems in social interactions and at work.

In order to be diagnosed with major depressive disorder, a person must have experienced at least one major depressive episode. Some people suffer a single episode, while others battle recurrent episodes. In some instances, the disorder is triggered by the birth of a baby. Approximately 3–6% of women experience depression starting during pregnancy or within weeks or months of giving birth; this is known as peripartum onset (American Psychiatric Association, 2013).

When making a diagnosis, the clinician must be able to distinguish the symptoms of major depression from normal reactions to a “significant loss,” such as the death of a loved one. This is not always easy because responses to death often resemble depression. A key distinction is that grief generally decreases with time, and comes in waves associated with memories or reminders of the loss; the sadness associated with a major depressive episode tends to remain steady (American Psychiatric Association, 2013).

Major depressive disorder is one of the most common and devastating psychological disorders. In the United States, for example, the lifetime prevalence of major depressive disorder is almost 17% (Kessler, Berglund, et al., 2005); this means that nearly 1 in 5 people experience a major depressive episode at least once in life. Women are more likely to be affected than men (Kessler et al., 2003), and rates of this disorder are already 1.5 to 3 times higher for females beginning in adolescence (American Psychiatric Association, 2013).

The effects of major depressive disorder extend far beyond the individual. For Americans ages 15 to 44, this condition is at the top of the list enumerating causes of disability (World Health Organization, 2008a)—and this means it impacts the productivity of the workforce. In a comprehensive study of major depressive disorder, respondents reported that their symptoms prevented them from going to work or performing day-to-day activities for an average of 35 days a year (Kessler et al., 2003). Stop and think about this statistic—we are talking about a loss of 7 work weeks!

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CULTURE Depression is one of the most common disorders in the world, yet the symptoms experienced, the course of treatment, and the words used to describe it vary from culture to culture. For example, people in China rarely report feeling “sad,” but instead focus on physical symptoms, such as dizziness, fatigue, or inner pressure (Kleinman, 2004). In Thailand, depression is commonly expressed through physical and mental symptoms, such as headaches, fatigue, daydreaming, social withdrawal, irritation, and forgetfulness (Chirawatkul, Prakhaw, & Chomnirat, 2011).

SUICIDE The recurrent nature of major depressive disorder creates increased risk for suicide and health complications (Monroe & Harkness, 2011). Around 9% of adults in 21 countries confirm they have harbored “serious thoughts of suicide” at least once (Infographic 12.2), and around 3% have attempted suicide (Borges et al., 2010). According to the National Institute of Mental Health (NIMH, 2013, October 1), approximately 90% of people who commit suicide have a psychological disorder, usually depressive disorder and/or substance abuse disorder.

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Nearly 7% of Americans battle depression in any given year (American Psychiatric Association, 2013; Kessler, Chiu, et al., 2005). What underlies this staggering statistic? There appears to be something biological at work.

GENETIC FACTORS Studies of twins, family pedigrees, and adoptions tell us that major depressive disorder runs in families, with a heritability rate of approximately 40–50% (American Psychiatric Association, 2013; Levinson, 2006). This means that about 40–50% of the variability of major depressive disorder in the population can be attributed to genetic factors. People who have a first-degree relative with this disorder are 2 to 4 times more likely to develop it than those whose first-degree relatives are unaffected (American Psychiatric Association, 2013).

NEUROTRANSMITTERS AND THE BRAIN Three neurotransmitters appear to be associated with the cause and course of major depressive disorder: norepinephrine, serotonin, and dopamine. The relationships among these neurotransmitters are complicated and research is still ongoing (El Mansari et al., 2010; Torrente, Gelenberg, & Vrana, 2012), but the findings are intriguing. For example, serotonin deficiency has been associated with major depressive disorder (Torrente et al., 2012), and genes may be responsible for some of this irregular activity, particularly in the amygdala and other brain areas involved in processing emotions associated with this disorder (Northoff, 2012).?Depression also seems to be correlated with specific structural features in the brain (Andrus et al., 2012). People with major depressive disorder may have irregularities in the amygdala, the prefrontal cortex, and the hippocampus. For example, some regions of the right cortex show significant thinning in people who face a high risk of developing major depressive disorder (Peterson et al., 2009). Studies have zeroed in on a variety of factors, such as increased structure size, decreased volume, and changes in neural activity (Kempton et al., 2011; Sacher et al., 2012; Singh et al., 2013). Research using functional magnetic resonance imaging (fMRI) technologies points to irregularities in neural pathways involved in processing emotions and rewards for people with major depressive disorder (American Psychiatric Association, 2013). Major depressive disorder most likely results from a complex interplay of many neural factors. What’s difficult to determine is whether changes in the brain precede the disorder, or the disorder alters the brain.

HORMONES There is also evidence that hormones play a role in depression. People with depressive disorders may have high levels of cortisol, a hormone secreted by the adrenal glands (Belmaker & Agam, 2008; Dougherty, Klein, Olino, Dyson, & Rose, 2009). Women sufferers, in particular, appear to be affected by stress-induced brain activity and hormonal fluctuations (Holsen et al., 2011). The hormonal changes associated with pregnancy and childbirth seem to be linked to major depressive episodes. For women suffering from depressive symptoms, there appear to be problems with the hypothalamic–pituitary–adrenal (HPA) system (Corwin & Pajer, 2008; Pearlstein, Howard, Salisbury, & Zlotnick, 2009). This is not just an issue for pregnant women. Research suggests that hyperactivity of the HPA system is linked to major depressive episodes in general (American Psychiatric Association, 2013).

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Earlier we mentioned heritability rates of 40–50% for depression. But what about the other 50–60% of the variability? Clearly, biology is not everything. Psychological factors also play a role in the onset and course of major depressive disorder.

LEARNED HELPLESSNESS According to researcher Martin Seligman, people often become depressed because they believe they have no control over the consequences of their behaviors (Overmier & Seligman, 1967; Seligman, 1975; Seligman & Maier, 1967). To demonstrate this learned helplessness, Seligman restrained dogs in a “hammock” and then randomly administered inescapable painful electric shocks to their paws (Figure 12.2). The next day the same dogs were put into another cage. Although unrestrained, they did not try to escape shocks administered through a floor grid (even though they could have, by jumping over a low barrier in the cage). Seligman concluded the dogs had learned they couldn’t control painful experiences during the prior training; they were acting in a depressed manner. He translated this finding to people with major depressive disorder, suggesting that they too feel powerless to change things for the better, and therefore become depressed.

NEGATIVE THINKING Cognitive therapist Aaron Beck (1976) suggested that depression is connected with negative thinking. Depression, according to Beck, is the product of a “cognitive triad”—a negative view of experiences, self, and the future. Here’s an example: A student receives a failing grade on an exam, so she begins to think she is a poor student, and that belief leads her to the conclusion that she will fail the course. This self-defeating attitude may actually lead to her failing the course, reinforcing her belief that she is a poor student, and perhaps evolving into a broader belief that her life is a failure.

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If you aren’t convinced that beliefs contribute to depression, consider this: The way people respond to their experience of depression may impact the severity of the disorder. People who repeatedly focus on this experience are much more likely to remain depressed and perhaps even descend into deeper depression (Eaton et al., 2012; Nolen-Hoeksema, 1991). Women tend to ruminate or constantly think about their negative emotions more than men, rather than using “active problem solving” (Eaton et al., 2012). Yet changing negative thoughts and moods during major depressive episodes is difficult to do without help. We should also note that a correlation between rumination and depression is not the same as a cause-and-effect relationship. Not every negative thinker develops depression, and depression can lead to negative thoughts.

We can think of mental health as a continuum, with healthy thoughts, emotions, and behaviors at one extreme, and dysfunction, distress, and deviance at the other. We can also conceptualize mood as a continuum, with a depressed mood at one end and neutral moods (not too sad, not too happy) in the center. But what lies at the other extreme? If it’s the opposite of depression, then it must be good, right? Not necessarily, as you will soon see.

LO 7 Compare and contrast bipolar disorders and major depressive disorder.

The extreme energy, euphoria, and confidence Ross felt were most likely the result of manic episodes, also known as mania. Manic episodes are often characterized by continuous elation that is out of proportion for the situation. Other features include irritability, very high and sustained levels of energy, and an “expansive” mood, meaning the person feels more powerful than he really is and behaves in a showy or overly confident way. During one of these manic episodes, a person exhibits three or more of the symptoms listed below, which represent deviations from normal behavior (American Psychiatric Association, 2013):

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It is not unusual for a person experiencing a severe manic episode to be hospitalized. Mania is difficult to hide and can be dangerous. One may act out of character, doing things that damage important relationships or jeopardize work. A person may become violent, posing a risk to himself and others. Seeking help is unlikely, because mania leads to impaired judgment, feelings of grandiosity, and euphoria. (Why would you seek help if you feel on top of the world?) At these times, the support of others is essential.

There are various types of bipolar disorder. To be diagnosed with bipolar I disorder, a person must experience at least one manic episode, substantial distress, and great impairment. Bipolar II disorder requires at least one major depressive episode as well as a hypomanic episode. Hypomania is associated with some of the same symptoms as a manic episode, but it is not as severe and does not impair one’s ability to function (American Psychiatric Association, 2013; Table 12.6).

BIPOLAR CYCLING Some people with bipolar disorder cycle between extreme highs and lows of emotion and energy that last for days, weeks, or even months. During bouts of mania, a person’s mood can be unusually elevated, irritable, or expansive. At the other extreme are feelings of deep sadness, emptiness, and helplessness. Periods of mania and depression may be brought on by life changes and stressors (Malkoff-Schwartz et al., 1998), though some research suggests that it is only the first episode that tends to be triggered by some sort of life event, such as a first love. Subsequent episodes do not seem to be as closely linked to such events (Belmaker, 2004).

Bipolar disorder is uncommon. Over the course of a lifetime, about 0.8% of the American population will receive a diagnosis of bipolar I disorder, and 1.1% bipolar II disorder (Merikangas et al., 2007). Men and women are equally likely to be affected, but men tend to experience earlier onset of symptoms, while the incidence for women seems to be higher later in life (Altshuler et al., 2010; Kennedy et al., 2005).

WHO GETS BIPOLAR DISORDER? Although researchers have not determined the cause of bipolar disorder, evidence from twin and adoption studies underscores the importance of genes. If one identical twin is diagnosed with bipolar disorder, there is a 40–70% chance the other twin will have the disorder as well. Among fraternal twins, there is only a 5% chance that the second twin will develop the disorder (Craddock, O’Donovan, & Owen, 2005). According to the American Psychiatric Association (2013), “a family history of bipolar disorder is one of the strongest and most consistent risk factors for bipolar disorders” (p. 130). Adults with a family member who has bipolar disorder, on average, have a “10-fold increased risk” for developing the disorder themselves.

But nature is not the only force at work in bipolar disorder; nurture seems to play an important role, too. The fact that there is a higher rate of bipolar disorder in high-income countries (1.4%) than in low-income countries (0.7%; American Psychiatric Association, 2013) suggests that environment may act as a catalyst for its development. Some researchers hypothesize that exposure to viruses, poor nutrition, and stress during fetal development spark a cascade of biological events that leads to the development of bipolar disorder. The same has been said of another serious disorder, schizophrenia (Carter, 2007; Yolken & Torrey, 1995).

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Question 1

Question 2

1. depression.

2. manic episodes.

3. panic attacks.

4. anxiety.

Question 3

Question 4