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It is now becoming increasingly apparent that bipolar depression -the depressed phase of bipolar disorder -is the predominant mood of this condition, and is probably responsible for much of the associated disability and morbidity [1]. Two recent reports from the National Institute of Mental Health Collaborative Depression Study have convincingly demonstrated that bipolar disorder patients experience depression much more frequently than hypomania or mania [2,3]. First, in a study focusing on patients with bipolar I disorder, Judd and colleagues reported on a follow-up of 146 patients over an average period of 12.8 years [2]. Assessing weekly symptom status, the authors found that patients experienced depressive symptoms for 32% of weeks over that period. This compared with only 9% of the time accounted for by hypomanic or manic symptoms and 6% for cycling or mixed presentations. When the depressive symptoms were examined in detail, it was apparent that most of this was not related to major depression, with 14% of weeks being due to minor depression or dysthymia, and 9% to subsyndromal depression. Only 9% of the time was experienced in major depression.
In the second paper, Judd and colleagues reported on the weekly symptomatic status in bipolar II patients from the same cohort [3]. In total, 86 patients were followed up for a mean of 13.4 years. In this population, depression was even more prevalent than in the bipolar I sample, accounting for 50% of weeks, compared with 1% of weeks in hypomania and 12% cycling or mixed. When the specific form of depression was examined, 24% of weeks were experienced in minor depression or dysthymia and 14% in subsyndromal depression. Again, major depression was relatively less common, accounting for only 13% of time.
Disability
It would appear that much of the disability due to bipolar disorder is related to the depressed component of this condition, with two recent studies indicative of this. First, in a US Veterans Affairs sample, Bauer and colleagues reported that the functional outcome of 143 bipolar disorder outpatients correlated significantly with their depressive, but not manic, symptoms [4]. Second, in a healthcare utilization study of a large US private insurer, Bryant-Comstock and colleagues, found that bipolar disorder patients utilized three- to four-times the healthcare costs of the average patient...