Emil Kraepelin, the German psychiatrist who coined the phrase “manic depression,” wrote that bipolar illness, in contrast to schizophrenia, usually has a good prognosis. In Kraepelin’s original sample of 459 patients, 45% had only one attack, and very few had more than four episodes. The average duration of a pharmacologically untreated manic episode was 7 months, but a wide range was reported. Although most later studies have validated Kraepelin’s findings, particularly when the disorder is compared to schizophrenia, it appears that the prognosis of bipolar illness is less favorable than originally reported. Up to 20% of patients respond inadequately to medication and must endure chronic or recurrent symptoms.
The phases of bipolar illness may differ in their responsiveness to treatment and in their effect on ultimate outcome. Some individuals, for example, experience complete remission of acute manic symptoms and benefit from prophylactic medication but continue to have unmodified or attenuated depressive episodes, with suicide being a significant risk.
The best predictor of cycle frequency and treatment response is the personal and family psychiatric history. Once the episode has resolved, the duration of the symptom-free interval varies greatly in different individuals. In contrast to Kraepelin’s original impression, it is now clear that most patients who satisfy the criteria for bipolar disorder will experience another episode within 2-4 years. The complete cycle—ie, from manic to depressed to manic state—may be as short as 48 hours or so long that the concept of cyclicity becomes meaningless. Patients with bipolar disorder who experience rapid cycles—three or more a year—respond less well to lithium than to anticonvulsants as compared to individuals with longer symptom-free intervals. The few available prospective studies of the course of bipolar illness indicate that for any given individual, the cycles become shorter as time goes on.
The prognosis thus depends on the frequency and duration of individual episodes and the response to medication. Because lithium is effective in moderating the severity of symptoms in most cases, there is always a strong possibility that recurrences represent failure of compliance with the drug regimen. Perhaps because of the quality of the mood experience, manic patients often utilize the psychological defense mechanism of denial, admitting that problems may exist but attributing them to overwork or to job or family stress. Patients with mild bipolar episodes may be able to function adequately during a period in which they demonstrate most of the symptoms of a manic episode. In such cases, factors such as psychological coping mechanisms, social supports, and socioeconomic status influence the outcome as much as response to medication.