The comparative short-term outcome of bipolar II disorder patients variably meeting or not meeting DSM-5 duration criteria following lamotrigine treatment

Abstract

There is accruing clinical and empirical evidence supporting the efficacy of lamotrigine as a treatment for bipolar II disorder. However, the treatment response experienced by those with ‘short duration’ hypomania (or ‘other specified’ bipolar disorder) has been under-researched. We reviewed a clinical sample of 123 patients diagnosed with a bipolar II disorder three months following their initial assessment. A research interview evaluated treatment strategies implemented, depressive and hypomanic episode pattern and functional outcomes. Of patients who had achieved a minimum level of 75 mg of lamotrigine, n = 51 were assigned to the BP II disorder group (i.e., hypomanic episodes lasted four days or longer) and n = 28 to the short duration group (i.e., hypomanic episodes always lasted less than four days). There were no significant differences between the two groups at the three-month follow-up on self-report measures of changes in depressive and hypomanic episode pattern or functioning across six domains (i.e., intimate relationships, family relationships, friendships, work relationships, work performance, overall quality of life), and with the majority of patients reporting some level of improvement. Study limitations include being an observational, uncontrolled design with a relatively small sample size for detecting statistical differences. Nonetheless, lamotrigine appeared to be a suitable medication to be trialled in patients who alternate between depressive episodes and short periods of hypomania, (as for those with DSM-defined hypomanic episodes), and should prompt further investigation.