Objectives: The risk-to-benefit ratio of the use of unimodal antidepressants (ADs) as adjuncts to mood stabilizers continues to be an area of controversy and disagreement among experts in the field. This paper reviews new data on: (1) depression in bipolar illness, (2) switch rates on ADs and (3) risks of AD discontinuation that are pertinent to the ongoing discussion and recommendations.
Methods: In the first study reviewed, 258 outpatients with bipolar illness were assessed prospectively on a daily basis using the National Institute of Mental Health-Life Chart MethodTM (NIMH-LCM) for 1 year. In the second study, 127 bipolar depressed patients were randomized to 10 weeks of sertraline, bupropion, or venlafaxine, as adjuncts to mood stabilizers; non-responders were re-randomized and responders were offered a year of continuation treatment. In the final study, Altshuler et al. retrospectively and prospectively assessed the risk of depressive relapses in patients who remained on ADs after 2 months of euthymia compared with those who discontinued ADs.
Results: Despite intensive naturalistic treatment, the 258 outpatients with bipolar illness followed prospectively for 1 year showed three times as many days depressed as days manic, re-emphasizing the considerable depressive morbidity that remains in bipolar disorder despite the number of treatment options available. In the study of bipolar depressed patients randomized to one of three ADs, a range of severities and durations of hypomanic to manic switches were discerned following 175 trials of AD augmentation of treatment with a mood stabilizer. Of the acute 10-week trials, 9.1% were associated with switches into hypomania or mania and another 9.1% with a week or more of hypomania alone (with no to minimal dysfunction). In 73 continuation phase AD trials, 16.4 and 19.2% were similarly associated with hypomanic to manic and hypomanic switches, respectively. In the Altshuler et al. studies, those who remained well on any AD for more than 2 months (only 15–20% of those initially treated) and who continued on ADs showed a lesser rate of relapse into depression over 1 year (35 and 36% in the first and second study, respectively) compared with those who discontinued their ADs (68 and 70% relapsing into depression). Surprisingly, this continuation of ADs was associated with no increase in the rate of switching into mania compared with those stopping ADs.
Conclusions: These data reveal that depression and depressive cycling remain a substantial problem in some two-thirds of intensively treated bipolar outpatients. Acute AD augmentation was associated with a modest response rate and 18.2% switched into a hypomanic to manic episode, and 35.6% of the continuation trials showed these two types of switches. Two separate studies suggest that in the very small subgroup who remain well on ADs for at least 2 months, one should consider continuation of this AD augmentation treatment, because AD discontinuation appears associated with a substantially increased risk of depression relapse over the subsequent year with no reduced risk of switching into mania.