A study published in the current issue of Psychotherapy and Psychosomatics addresses the cognitive status of people who suffer from mood swings (bipolar disorder). While neuropsychological impairment in bipolar disorder is well documented, the effect size of this impairment is rarely compared directly to that in other clinically familiar cognitive disorders.
This study compares neuropsychological functioning of euthymic bipolar patients to those with mild cognitive impairment (MCI) as well as healthy controls. In every domain, the healthy control group outperformed both the bipolar and the MCI groups. The cognitive function of euthymic bipolar patients and those diagnosed with MCI was found to be similar in most but not all domains.
Following evaluation during regular follow-up in a mood disorders clinic, 58 euthymic adult bipolar subjects were administered a validated and fully computerized cognitive assessment (Mindstreams; NeuroTrax Corp., N.Y., USA). Study data were compared to existing data for MCI and cognitively healthy individuals tested with the same assessment. Final analyses were based on 51 bipolar patients, 162 MCI patients and 495 healthy comparison subjects. Significant (p < 0.001) group effects were found for every parameter.
Post hoc analysis revealed that the bipolar and MCI groups showed statistically equivalent functioning in memory, executive function, verbal function, and information processing speed. In the domains of visual-spatial processing, attention, and motor skills, the MCI group outperformed the bipolar group.
In every domain, the healthy control group outperformed both the bipolar and the MCI groups. The cognitive function of euthymic bipolar patients and those diagnosed with MCI was found to be similar in most but not all domains. Both groups performed significantly less well than the comparison group of healthy subjects. It may be helpful for clinicians to conceptualize the overall level of cognitive impairment in bipolar patients as similar to that in MCI.
