BackgroundIt has not been examined trialed whether obsessive compulsive symptoms in patients with bipolar disorder respond to topiramate as an adjuvant treatment. MethodsThis 4-month double-blind placebo-controlled randomized clinical trial examined the efficacy and safety of augmentation with topiramat for treating the patients with bipolar disorder, manic phase type-I, and obsessive compulsive disorder symptoms. Both groups received lithium+olanzapine+clonazepam. However, one group received topiramate and the other group placebo as adjuvant medications. Yale Brown obsessive compulsive behavior scale was used to assess the outcome. Adverse effects were also recorded. ResultsA total of 32 patients completed this trial. The mean score decreased from 24.2(4.8) to 17.6(8.7) in the topiramate group (P<0.003) and from 20.9(2.9) to 9.6(3.5) in the placebo group during this trial (P<0.0001). Additionally, 9(52.9%) out of 17 patients in the topiramate group and 2(12.5%) out of 16 patients in the placebo group showed more than 34% decline in YBOC score (x2=6.0, df=1, P<0.01). No serious adverse effects were detected. LimitationsThe limitations of the present study were its small sample size and the fact that it was conducted in a single center. ConclusionsThe combination of lithium+olanzapine+clonazepam decreased the symptoms of obsessive compulsive disorder in the patients with bipolar disorder type I. However, topiramate had a more significant effect than placebo on improvement of the patients with bipolar disorder and obsessive compulsive symptoms. This combination seems to be without serious adverse effects.