Reviewed by Michael Fuller, M.D.
Depression is a whole-body illness, involving your body, mood, and thoughts. It affects the way you eat and sleep, the way you feel about yourself, and the way you think about things. Without treatment, symptoms can last for weeks, months, or years.
Depression manifests as a combination of symptoms that interfere with the ability to work, sleep, eat, and enjoy once pleasurable activities. These disabling episodes of depression can occur once, twice, or several times in a lifetime.
Depression can run in families, indicating that a biological vulnerability can be inherited. Major depression seems to occur, generation after generation, in some families. However, it can also occur in people who have no family history of depression. Whether inherited or not, major depressive disorder is often associated with having too little or too much of certain neurochemicals.
Psychological makeup also plays a role in vulnerability to depression. People who have low self-esteem, who consistently view themselves and the world with pessimism, or who are readily overwhelmed by stress are prone to depression.
A serious loss, chronic illness, difficult relationship, financial problem, or any unwelcome change in life patterns can also trigger a depressive episode. Very often, a combination of genetic, psychological, and environmental factors is involved in the onset of a depressive disorder.
