Low body mass index is associated with higher rates of mild cognitive impairment and worse memory performance among older Canadian adults: An analysis of the Canadian Longitudinal Study on Aging (CLSA) database.

BackgroundBoth 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.ObjectiveThis 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.MethodsThis 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.ResultsIn 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.ConclusionsBeing underweight is linked to higher odds of MCI, suggesting the importance of adequate nutrition in preserving cognitive health among older adults.