Education, Inflammation Predict Cognitive Performance in Bipolar Disorder

Level of education and certain inflammatory markers can serve as effective predictors of cognitive performance in patients with bipolar disorder, according to results of a study published in the Journal of Psychiatric Research.

Researchers set out to examine how bipolar disorder affects cognitive performance across a variety of clinical parameters. A sample of 20 patients with bipolar disorder who were in remission was assessed using the Mini-Mental State Examination and Brief Assessment of Cognition in Affective Disorders. In addition, blood was drawn from each patient to measure plasma cytokines, using the cytometric bead arrays kit. The results of each test were compared with a control group matched by age, sex, and years of education. The researchers noted the potential role of education as it relates to the brain’s resilience in response to neuropathological changes, otherwise known as “cognitive reserve,” stating, “[o]ne of the major determinants of cognitive reserve and cognitive performance throughout the lifespan is education.”

Patients with bipolar disorder performed more poorly in various Verbal Memory Trials, the Digit Sequence Task, Semantic Fluency, and Tower of London (all P <.0025) when compared with the control group. Brief Assessment of Cognition in Affective Disorders global cognitive performance was positively correlated with Mini-Mental State Examination (P =.008; rho, 0.578) and years of study (P =.023; rho, 0.507), and it was negatively correlated with duration of illness (P =.019; rho, −0.518). Of the inflammatory markers, only interleukin 6 correlated significantly with Brief Assessment of Cognition in Affective Disorders global performance (P =.047; rho, −0.461). The final multiple regression model with years of education, Mini-Mental State Examination, and interleukin 6 predictors was statistically significant [R², 0.734; F(3, 3.06), 13.76; P <.001).

Some limitations of the study include the exclusion of patients with certain medical conditions, which led to a more homogenous sample. The study’s cross-sectional nature makes it impossible to draw conclusions about causation, and because the patients had long illness duration, generalizability to milder or early forms of bipolar disorder is limited.

In addition to their potential to signify cognitive performance, the researchers concluded that formal education and reduced inflammation may even be protective factors against cognitive impairment in patients with bipolar disorder.

Reference

Barbosa IG, de Almeida RF, Rocha NP, et al. Predictors of cognitive performance in bipolar disorder: The role of educational degree and inflammatory markers. J Psychiatric Res. 2018;106:31-37.