Depression is a very widespread problem today affecting one in four women and one in eight men. Many people are aware of the many symptoms of depression, including feelings of hopelessness or helplessness, obsessive negative thoughts, loss or gain in appetite, insomnia or an increased need for sleep, social withdrawal, irritability and loss of memory or concentration, and recurrent thoughts of death or suicide. It is tempting to think that depression is sadness and the causes of depression will simply disappear and the negative feelings will subside. However, the causes of depression are not so simple, and while a negative event may trigger depression, the causes of depression are not external factors alone. Many of the causes of depression are issues with the sufferer.

Causes of depression are 40 – 70% hereditary and children of depressed children are more likely to be depressed. This would mean that the potential for depression lies in one's genetic makeup, and a stressor may trigger a latent potential for depression. However those who dispute heredity as one of the causes of depression cite other true observations that those who live with depressed individuals are more likely to be depressed, and a depressed parent may lack parenting skills or the necessary energy or patience to deal with a child properly, and may be one of the causes of depression. It is hard to know who really wins the nature versus nurture argument, but once we learn more about the role heredity plays among the causes of depression, the better we will understand how genes have an impact on our moods.

Whether causes of depression are hereditary or not, there is a physiological basis for the problem, which refutes claims that depression is nothing more than a bad mood that will pass. Low serotonin levels have been shown to be one of the causes of depression, and loss of neurotransmitters in the hippocampus has also been identified as one of the causes of depression. Seasonal affective disorder is also one of the causes of depression, and it has been shown that those who are deprived of light and warmth in the wintertime and become depressed as a result are not merely suffering from the “winter blues" but have a problem caused by the shorter days and longer nights. Seasonal effective disorder can develop into full blown depression if it not treated as one of the series causes of depression. Hormones may also play a role as one of the causes of depression, especially among those women who suffer from Pre Menstrual Syndrome or post-partum depression. In fact, while one out of every four women suffers from depression compared to one in every eight men, this discrepancy disappears among women who have undergone menopause, when there are lower levels of estrogen. More study is needed to determine whether these hormonal fluctuations are actual causes of depression, or merely triggers.

Losing one's job, getting a divorce or a death in the family may not be actual causes of depression, but they can trigger the problem in those who have a predisposition for the problem. Certainly, such events can cause sadness and a feeling of worthlessness, but if these feelings are not persistent, they are normal aspects of the grieving process and are not causes of depression. However, if the negative feelings are prolonged and obsessive, they may be triggers in setting off depression. There are some physical aliments which are included among causes of depression. Hepatitis and heart conditions can be causes of depression, in addition to Aids and other illnesses which cause weakness and fatigue.