BMI may affect cognitive impairment after stroke

Patients with higher or lower BMIs faced significantly greater risks for global cognitive function and frontal domain performances following an ischemic stroke, according to a study published in Scientific Reports.

“BMI might differentially affect cognitive domains after ischemic stroke,” Minwoo Lee, of the department of neurology at Hallym Neurological Institute in South Korea, and colleagues wrote. “Although being underweight may negatively affect global cognition post-stroke, obesity could induce frontal lobe dysfunctions, specifically phonemic and semantic word fluency.”

Lee and colleagues evaluated 335 patients who survived an ischemic stroke. After patients completed the Korean-Mini Mental Status Examination and the vascular cognitive impairment harmonization standards neuropsychological protocol at 3 months following their stroke, the researchers analyzed patients’ frontal lobe functions using semantic and phonemic fluency, processing speed and mental set shifting. Investigators stratified patients into four groups based on BMI, with quartile 1 (Q1) having the lowest BMIs (< 21.87 kg/m²) and Q4 having the highest (> 25.97 kg/m²).

The average age of patients was 64.8 years, and 38.9% were women. The mean BMI was 23.89 kg/m², with a range of 15.82 kg/m² to 32.93 kg/m². Patients’ stroke severity did not differ significantly. Lee and colleagues found that hypertension was more common among patients in the Q4 group compared with those with lower BMIs. Also, patients in the Q1 group showed significantly lower global cognitive functions than those in the Q2 and Q4 BMI groups. The Q4 group demonstrated significantly lower phonemic and semantic word fluencies than those in Q2, although their levels of global cognitive function were similar. Overall, Lee and colleagues’ analysis revealed that a lower BMI correlated with a higher risk for global cognitive impairment, and a higher BMI correlated with significantly worse frontal dysfunction.

“To our knowledge, this study is the first to evaluate BMI and domain-specific cognitive outcomes using a comprehensive, standardized, neuropsychological protocol in relation to a multicenter cohort of stroke patients,” Lee and colleagues wrote. They added, “Taken together, lower BMI and higher BMI may have differential pathophysiological roles in cognitive impairment after stroke.”