Background Both low and high body mass index (BMI) have been identified as risk factors for dementia, though the association between the range of BMI classifications and presence of mild cognitive impairment (MCI) and memory performance warrants further investigation. Objective This study aimed to investigate the association between the range of BMI classifications and presence of MCI, as well as overall memory performance, among a large Canadian sample of older adults. Methods This study utilized data from 40,232 participants from the Canadian Longitudinal Study on Aging (CLSA). The association between BMI and cognitive function was examined at baseline and first follow-up (3 years). Linear regression was used to model the relationship between BMI and memory performance, while logistic regression was used to assess the association between BMI and the odds of meeting criteria for MCI. Results In the final regression model, a weak (partial eta-squared=0.8%, 95% CI 0.63%, 0.97%) inverted-U relationship between BMI and REYII memory performance was demonstrated, with normal BMI showing the best performance. In the final logistic regression model, being underweight was associated with 3.22 times greater odds (95% CI 1.63, 6.39) of meeting criteria for MCI compared to normal BMI. No association was demonstrated between change in BMI and change in cognitive performance between baseline and 3-year follow-up. Conclusions Being underweight is linked to higher odds of MCI, suggesting the importance of adequate nutrition in preserving cognitive health among older adults.
Akbar et al. (Sat,) studied this question.