The nature and severity of cognitive alterations can vary significantly between different mood disorders, according to Dr. Charles Cotrena and his associates.

The study of 205 Brazilians comprised patients with major depressive disorder (MDD), patients with bipolar disorder I (BDI) and II (BDII), and a healthy control group, all of whom took a battery of neurocognitive tests. MDD patients performed poorly in tests involving attention and timed tasks, compared with the control group, but had less motor inhibition than did patients with BDI. Patients with BDI tended to perform worse across all executive functions, compared with patients with MDD, BDII, and the control group; however, BDII patients were the only ones who performed worse on the Iowa Gambling Task than did the control group, and performed worse on the Stroop Color–Word Test than did BDI patients.

While MDD patients had worse psychological quality of life (QOL) than that of controls, there was no difference in other QOL measures. MDD patients reported better physical health and lower disability rates than did BD patients. BDII patients had worse QOL than did control patients, but had lower disability rates than did BDI patients.

The investigators found that differences in cognitive function and quality of life still existed in patients with mood disorder, even after adjustment for mania and depressive symptoms.

“The importance of a detailed assessment of [executive function] and disability levels within each of these diagnostic categories, while controlling for demographic variables, was especially evident from the current results. Additionally, the comparison of impairment rates between groups – which is not a usual measure in the literature – provided important contributions to current knowledge regarding cognition and mood disorders,” the investigators noted.

Find the study in the Journal of Affective Disorders (doi: 10.1016/j.jad.2015.11.007).