The investigators of a study in the Journal of Affective Disorders examined the impact of comorbid bipolar disorder and obsessive-compulsive disorder (OCD) on cognitive functioning and found that the presence of both these disorders was not associated with worse impairment than either disorder alone.
Previous research has demonstrated that OCD and bipolar disorder frequently co-occur, especially in individuals with type II bipolar disorder. The investigators anticipated that comorbidity would lead to further impairment in skills such as cognitive flexibility, set-shifting, and decision making.
Participants with bipolar disorder (n=22), OCD (n=20), and both disorders (n=26) were recruited from the inpatient unit at the University Hospital Mater Domini in Catanzaro, Italy. Participants were adults age ≤65 years without any substance dependence or misuse disorder, neurological condition, or medical condition. They were in remission at the time of the study as defined by a Clinical Global Impression score ≤2.
Symptoms severity was rated on the Young Mania Rating Scale, Hamilton Depression Rating Scale, and Yale-Brown Obsessive Compulsive Scale.
Cognitive testing revealed no between-group differences in skills such as decision making and cognitive flexibility, although participants with OCD had non-significantly higher test scores across the board — perhaps due to the perfectionism characteristic of the disorder.
Patients with bipolar disorder demonstrated somewhat lower scores on the Rey-Osterrieth Complex Figure Test, which rates accuracy, as well as slower response times on the Hayling Sentence Completion Test. The investigators pointed to difficulty sustaining attention in patients with bipolar disorder.
The study was limited by its relatively small sample size and cross-sectional design; the investigators suggested additional studies examine the longer-term impact of treatment in this patient population.
Investigators noted, future research will reveal “the reason why two severe disorders with different etiopathogenesis, pathophysiologic mechanisms, and neurobiological circuits…presented similar deteriorated neurocognitive profiles, both individually and in comorbidity.”
Filippis R, Aloi M, Bruni A, et al. Bipolar disorder and obsessive compulsive disorder: The comorbidity does not further impair the neurocognitive profile. J Affect Disord. 2018: 235:1-6.