Answer:
The cycle of depressed thinking has four steps: 1) stressful experiences 2) negative explanatory style 3) depressed mood and 4) cognitive and behavioral changes. The steps repeat as part of a vicious cycle. Depression changes both thoughts and behaviors. Depression is widespread; as many as 10 percent of Americans suffer from depression, with women suffering at nearly twice the rate as men. Most depression episodes self-terminate, meaning they do not require the intervention of medicine or therapy. Stressful conditions related to work, marriage, and close relationships often precede depression. Depression is striking earlier with each successive generation. Genetics seems to play a role in depression. There is a 30 percent heritability estimate for depression. Other factors, like biological influences, seem to be associated with depression. For instance, diminished brain activity is associated with depression. Norepinephrine levels are lower with depression, and serotonin may play a role as well. Social-cognitive perspectives can play a role in depression as well. Negative thoughts (such as rumination: staying focused on the problem) can contribute to negative moods and can reinforce each other. Also, an explanatory style that includes a negative, stable, and global assessment of the issue can contribute to learned helplessness, a condition in which a person sees no way to change a situation, reinforcing the negativity of thought.