Emotional and physical withdrawal are common responses of depressed people. Depression can strike at any time, but most often appears for the first time during the prime of life, from ages 24 to 44. One in four women and one in 10 men will confront depression at some point in their lives. Several factors play a role in the onset of depression. Deficiencies in two chemicals in the brain, serotonin and norepinephrine, are thought to be responsible for certain symptoms of depression, including anxiety, irritability, and fatigue.
Depression can run in families.
People with low self-esteem, who are easily overwhelmed by stress, or who are generally pessimistic appear to be vulnerable to depression. Continuous exposure to violence, neglect, abuse, or poverty may make people who are already susceptible to depression all the more vulnerable to the illness. However, it should be noted that depression can still occur under ideal living circumstances. Unfortunately, depression cannot be controlled for any length of time simply through exercise, through changes in diet, or by taking a vacation. But it is among the most treatable of mental disorders.