Reducing Inflammation May Boost Cognitive Performance

A new study from Harvard Medical School and Brigham and Women’s Hospital reports that a marker for systemic inflammation called C-reactive protein (CRP) was significantly higher among a subgroup of patients with poor cognitive performance. These findings were published on November 19 in the journal Molecular Psychiatry.

This research was prompted by the observation that even when episodes of depression and mania were being controlled in patients with bipolar disorder (BD), some patients showed cognitive resilience and others (inexplicably) appeared to experience more rapid cognitive decline.

Previous research has identified a possible link between systemic inflammation and cognitive performance. Therefore, the Brigham and Women’s team decided to conduct more pioneering research on the possible association between C-reactive protein and cognitive performance in a large cohort of euthymic (i.e., stable mental state) patients with bipolar disorder and a control group.

The cohort of this study consisted of 222 euthymic bipolar disorder (BD-I and BD-II) patients whose mood was clinically stable. The researchers also enlisted a control group of 52 healthy adults.

For this study on a possible association between inflammation levels and cognitive function, the researchers conducted a battery of cognitive performance tests called the MATRICS Consensus Cognitive Battery (MCCB) and measured CRP levels in all 274 study participants.

The MCCB is a neuropsychological assessment tool that measures seven cognitive domains: speed of processing; attention/vigilance; working memory;) verbal learning; visual learning; reasoning and problem-solving; and social cognition.

The cognitive performance test results from all participants were subdivided into those with high CRP (≥5 mg/L) versus the remaining subjects with CRP levels less than 5 mg/L.

The authors explain the association between C-reactive protein inflammation markers and cognitive performance scores: "We found a statistically significant effect of CRP on cognitive performance on a broad range of tests; participants with CRP ≥5 mg/L had worse performance on several measures of executive functioning, processing speed and reasoning, and problem-solving relative to those with lower CRP."

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"We know that one person with bipolar disorder may be very different from another, and these findings support this. Levels of inflammation varied in patients, but among those with high levels of inflammation, we saw the strongest evidence of cognitive impairment," co-author Katherine Burdick of Brigham’s Department of Psychiatry and director of the Mood and Psychosis Research Program said in a news release. "Hundreds of things can contribute to cognitive decline, from poor sleep to lack of exercise to poor diet. There's mounting evidence that inflammation may be an important driver, too."

The main takeaway of this study is that lower levels of CRP may be linked to better cognitive performance. On the flip side, higher levels of CRP appear to be associated with cognitive deficits. Also, ≥5 mg/L of C-reactive protein may be a predictor of both systemic inflammation and an increased risk of cognitive decline.

Based on a growing body of evidence (Balter et al., 2019), one could speculate that treatments designed to reduce inflammation have the potential to boost cognitive performance and ward off cognitive decline. (See “Is Low-Grade Inflammation Making You Mentally Sluggish?”)