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51-1 How do major depressive disorder, persistent depressive disorder, and bipolar disorder differ?

Most of us will have some direct or indirect experience with depression. If you are like many college students, at some time during this year—more likely the dark months of winter than the bright days of summer—you may experience some of depression’s symptoms. You might feel deeply discouraged about the future, dissatisfied with your life, or socially isolated. You may lack the energy to get things done or even to force yourself out of bed; be unable to concentrate, eat, or sleep normally; or even wonder if you would be better off dead. Perhaps academic success came easily to you before, but now you find that disappointing grades jeopardize your goals. Maybe social stress, such as loneliness, feeling you are the target of prejudice, or experiencing a romantic breakup, have plunged you into despair. And perhaps low self-esteem increases your brooding, worsening your self-torment (Sowislo & Orth, 2012). Likely you think you are more alone in having such negative feelings than you really are (Jordan et al., 2011). In one national survey of American collegians, 31 percent said they had at some time in the past year, “felt so depressed that it was difficult to function” (ACHA, 2009). Misery has more company than most suppose.

Joy, contentment, sadness, and despair exist at different points on a continuum, points at which any of us may find ourselves at any given moment. To feel bad in reaction to profoundly sad events is to be in touch with reality. In such times, there is an up side to being down. Sadness is like a car’s low-fuel light—a signal that warns us to stop and take appropriate measures. Biologically speaking, life’s purpose is not happiness but survival and reproduction. Coughing, vomiting, swelling, and pain protect the body from dangerous toxins. Similarly, depression resembles a sort of psychic hibernation: It slows us down, defuses aggression, helps us let go of unattainable goals, and restrains risk taking (Andrews & Thomson, 2009a,b; Wrosch & Miller, 2009). When we grind temporarily to a halt and reassess our life, as depressed people do, we can redirect our energy in more promising ways (Watkins, 2008). We may also make better decisions. Even mild sadness can improve people’s recall, make them more discerning, and help them make complex decisions (Forgas, 2009). It can also help them process and recall faces more accurately (Hills et al., 2011). There is sense to suffering.

But sometimes this response, taken to an extreme, can become seriously maladaptive and signal a disorder. The difference between a blue mood after bad news and a depression-related disorder is like the difference between gasping for breath after a hard run and being chronically short of breath.

In this module, we consider three disorders in which depression impairs daily living:

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