Risk Factors

Traumatic events such as abuse or even natural disasters can cause severe immediate or delayed depression from which recovery takes a long time.

Accompanying Medical Disorders

Severe or Chronic Medical Conditions. Any chronic or serious illness that is life-threatening or out of a person's control can lead to depression.

Thyroid Disease. Thyroid disease can cause depression; however, it may be misdiagnosed as depression and go undetected.

Headaches. Studies have reported a strong association between depression and headaches, including chronic tension-type and migraine. Some experts believe that a syndrome of migraine headaches (and also possibly tension-type), anxiety, and depression, is caused by common factors, such as abnormalities in chemical messengers, particularly dopamine or serotonin.

Stroke. Having a stroke increases the risk of developing depression.

Medications

A number of drugs taken for chronic problems cause depression. Among them are pain relievers for arthritis, cholesterol-lowering drugs, medications for high blood pressure and heart problems, and bronchodilators used for asthma and other lung disorders.

Smoking

There is a significant association between cigarette smoking and a susceptibility to depression. People who are prone to depression face a 25% chance of becoming depressed when they quit smoking, and this increased risk persists for at least 6 months. What's more, depressed smokers are unlikely to stop smoking. Only about 6% remain smoke-free after a year. Smokers with a history of depression are not encouraged to continue smoking, but rather to keep a close watch on recurrence of depressive symptoms if they do stop smoking. The antidepressant bupropion (Wellbutrin), which is approved for helping people quit smoking (marketed under the name Zyban), is proving to be very useful in helping smokers to quit.

Anxiety Disorder

Chronic depression is a frequent companion to anxiety disorders. In one study, up to 96% of patients with depressive disorders experienced concurrent anxiety. More than two-thirds of people with obsessive-compulsive disorder, a common anxiety disorder, also suffer from depression.

Personality Characteristics and Disorders

Some evidence suggests that certain personality styles, which include an intense need for close relationships and concern for disapproval or need for control, pose a high risk for depression, particularly after an adverse life event. In line with these findings, the following specific personality disorders have been associated not only to a first episode of depression, but also to relapses:

• A person with borderline personality disorder acts impulsively and has a poor self-image and unstable relationships. In one study, patients with borderline personality disorder and major depression were more likely than those with either condition alone to plan and attempt suicide.
• An individual with an avoidant personality avoids strangers and unfamiliar situations.