Residual anxiety may be associated with depressive relapse during continuation therapy of bipolar II depression

Anxiety symptoms are common in bipolar disorder. We explored the effect of anxiety on the outcome of acute and continuation pharmacotherapy of bipolar II depression.

Data were derived from a randomized double-blind 12-week acute (N = 129) and 6-month continuation (N = 55) comparison of venlafaxine versus lithium monotherapy in bipolar II depression in adults. We distinguished between the items of the Hamilton Rating Scale for Depression (HRSD) that capture depression vs. anxiety (i.e., psychomotor agitation, psychic anxiety, somatic anxiety, hypochondriasis, and obsessive-compulsive concerns) and examined the effect of treatment on depression and anxiety. Additionally, we explored whether baseline anxiety or depression predicted changes over time in depression and anxiety ratings or moderated treatment outcomes. We also explored whether residual depressive and anxious symptoms predicted relapse during continuation therapy.

Venlafaxine was superior to lithium in reducing both depression and anxiety, though its effects on anxiety were more modest than those on depression. Baseline anxiety predicted change over time in anxiety, but not depression. By contrast, baseline depression did not predict change over time in depression or anxiety. Residual anxiety, specifically uncontrollable worry, was a stronger predictor of relapse than residual depression.

Successful treatment of symptoms of anxiety in bipolar depression may protect against depressive relapse.