Unfortunately, it is not fully known what exactly causes clinical depression. There are numerous theories about causes such as biological and genetic factors, environmental influences, and childhood or developmental events. However, it is generally believed that clinical depression is most often caused by the influence of more than just one or two factors. For instance, a person whose mother had recurrent major depression may have inherited a vulnerability to developing clinical depression (genetic influence). This combined with how the person thinks about him- or herself (psychological influence) in response to the stress of going through a divorce (environmental influence), may put him or her at a greater risk for developing depression than someone else who does not have such influences.

The causes of clinical depression are likely to be different for different people. Sometimes a depressive episode can appear to come out of nowhere at a time when everything seems to be going fine. Other times, depression may be directly related to a significant event in our lives such as losing a loved one, experiencing trauma, or battling a chronic illness.

Risk Factors for Depression

Related to the discussion of the causes of clinical depression is something called, "risk factors." Essentially, we are all at risk for developing a depressive illness. People of all ages, races, and social class can become clinically depressed. No one is completely immune to this condition. However, it is important to know that the more common illnesses of major depression and bipolar disorder do tend to affect some groups of individuals more so than others. Some features of these groups, when associated with the development of a depressive illness, are known as "risk factors."
Please remember that no one is predestined to develop clinical depression. However, it can be very important to be aware of risk factors so that those of us who may be vulnerable can educate ourselves, be attentive to warning signs, and take steps towards recognizing and preventing this illness.

Risk Factors For Major Depression

Gender: In the United States, women are about as twice as likely as men to be diagnosed and treated for major depression. Approximately 20-25% of women and 12% of men will experience a serious depression at least once in their lifetimes. Among children, depression appears to occur in equal numbers of girls and boys. However, as girls reach adolescence, they tend to become more depressed than boys do. This gender difference continues into older age.  There are several theories as to why more women than men are diagnosed and treated for depression:

•    Women may be more likely than men to seek treatment. They may be more willing to accept that they have emotional symptoms of depressed mood and feelings of worthlessness or hopelessness.

•    Men may be less willing to acknowledge their emotional symptoms and more apt to suppress their depression through the use of alcohol or other substances. In such cases depression can be "masked," or viewed only as alcohol or drug dependency/abuse rather than as clinical depression.


•    Women may tend to be under more stress than men. In today's American society women often have to manage a variety of conflicting roles. They have many responsibilities and full schedules at home and work.

•    Women may be more prone to depression because of the possible effects of hormones. Women have frequent changes in their hormone levels, from their monthly menstrual cycles, to the time during and after pregnancy, to menopause. Some women develop a depressive illness around these events.

Marital factors: Women who are unhappily married, divorced, or separated, have high rates of major depression. The rates are lower for those who are happily married.
Age: While clinical depression usually occurs for the first time when a person is between the ages of 20 and 50, people over the age of 65may be especially vulnerable.

Previous episode: If you have had major depression once before, your chances of developing it again increase. According to some estimates, approximately one-half of those who have developed depression will experience it again.

Heredity: People who have relatives who have had clinical depression have a greater chance of developing it themselves. Also, having a close relative with bipolar disorder may increase a person's chances of developing major depression.

Medical Causes

Many central nervous system illnesses and injuries can also lead to depression. For example, depression might be associated with any of the following conditions:
•    central nervous system tumors
•    head trauma
•    multiple sclerosis
•    stroke
•    syphilis
•    various cancers (pancreas, prostate, breast)

Side effects from medications can lead to depression.  Corticosteroid medications such as prednisone, which people take for diseases such as rheumatoid arthritis or asthma, are also associated with depression. Many blood pressure medicines can cause depression as well as acne medications like accutane. Other drugs, including illegal steroids and amphetamines and over-the-counter appetite suppressants, may cause depression on withdrawal.  You should ask your physician if any of your medications could have the side effect of depression.
Hormone imbalances, such as thyroid, testosterone, prolactin, estrogen, and progesterone all play a role in mood.