There is no single cause for depression. Many factors play a role including genetics, chemical imbalance, stress, physical illness and negative thinking patterns which affect a person’s reaction to events.
Depression runs in families, and the more closely related one is to the depression sufferer, the higher the chances of developing depression.
Some of the symptoms of depression may be caused by abnormal secretion of hormones such as thyroid and parathyroid hormones, or a disruption in the delicate balance in the hypothalamus, pituitary and adrenal glands.
It has been postulated that in depression, there is insufficient transmission of nerve impulses involving certain neurotransmitters such as noradrenaline, serotonin and possibly dopamine. Research has firmly established that life events are associated with the onset of depression. Events such as loss of a loved one, business failure and broken relationships are common examples. Depressed patients report an increase of life events in the last six months before the onset of depressive symptoms.
Certain personality traits predispose a person to depressive illnesses. Obsessive compulsive traits are characterized by perfectionism, in particular, setting impossibly high standards which results in repeated disappointments when the standards are not met. Dependent personalities have a great need to be taken care of and depend on others to make decisions or to do things for them. Borderline personalities are characterized by unstable interpersonal relationships, poor self-image, and overwhelming fears of abandonment.
Substance abuse can cause chemical changes in the brain that affect mood (alcohol and some drugs are known to have depressogenic effects). The negative social and personal consequence of substance abuse can also lead to family disruption and discord.
Medical conditions associated with depression include:
In females, depression is more common in the married than the never-married groups. In males, the single, divorced and widowed are more likely to be depressed.
Women have a relatively higher rate of occurrence of depression than man.
Depression is more common in those in the lower income group. The retired, unemployed or part-time employed are more likely to be diagnosed with depression. Those living alone are also at a higher risk.
People who become clinically depressed have generally experienced more severe difficulties in childhood than those who do not become depressed.