Here's what you need to know about the history and prognosis of depression and bipolar disorder.

Mood disorders most often surface between ages 20 and 30 but they can occur at any age. An accurate diagnosis of depression or bipolar disorder is often delayed because symptoms are typically not recognized as being related to an illness; instead, they are thought to be a reaction to life circumstances.

Natural History of Depression

An untreated episode of major depression usually lasts eight to nine months. This period can be shortened considerably with proper diagnosis and treatment. Most people with depression have their first episode before age 40, and most will have more than one episode in their lifetime. Relapse rates are lower in people who continue with treatment when they are feeling well. Approximately 10 percent of depressed people have a chronic form of depression that is resistant to current treatments.

Alcoholism or other drug use can make recovery from depression (and bipolar disorder) more difficult. A recent study compared 176 men and women who fit the criteria for both alcoholism and major depression with 412 people who had major depression alone. Those who had never been alcoholics or who no longer drank were twice as likely to recover from an episode of major depression than those who were still drinking. Unfortunately, many depressed people slow their recovery by attempting to self-medicate with alcohol.

Natural History of Bipolar Disorder

Bipolar disorder usually begins at an earlier age than depression and can even occur in childhood. But it is also an unpredictable disease that can emerge later in life. In one large study of people treated at Veterans Affairs hospitals, 25 percent of the more than 65,000 people with bipolar disorder treated during one year were age 60 or older. And in this over-60 age group, approximately 6 percent had new-onset disease.

In a second study, about 10 percent of 1,157 people between the ages of 18 and 70 treated in an urban primary care clinic screened positive for bipolar disorder. Of those, 41 percent reported first being affected at age 40 or older.

Overall, men and women are equally likely to suffer from bipolar disorder, but women may be more likely to experience the late-onset form. A study of 48 older adults with bipolar disorder showed that women were almost three times as likely to be in the late-onset group.

About two thirds of people with bipolar disorder who recover completely from an acute episode have recurrent bouts of either depression or mania. Half of these recurrences tend to be manic, even when the first episode is depression. Although the average number of recurrences is four, this number can vary significantly from person to person. The episodes can be separated by weeks, months, or years. Over time, recurrences tend to happen more frequently, and they may become more severe.

Some people with bipolar disorder can cycle between depressive and manic episodes as often as four times a year (this is known as rapid cycling). There is tremendous variability in the course of the condition, with some people experiencing full recovery between episodes and others experiencing chronic (ongoing) symptoms.

Publication Review By: Karen L. Swartz, M.D.

Published: 03 Mar 2011

Last Modified: 28 Jan 2015