Age Modulates the Association of Caffeine Intake With Cognition and With Gray Matter in Elderly Diabetics.

Background: The association between caffeine and cognitive performance has not been tested in older individuals with type 2 diabetes (T2D). Its association with brain volume in T2D has been tested only in animals. Methods: We examined the association of caffeine with cognitive function and brain volume in a sample of elderly diabetics participating in the Israel Diabetes and Cognitive Decline Study (n=638) and the moderating effect of age on this association. In a subsample (n=185) with magnetic resonance imaging, we also examined these associations with gray and white matter volumes (GM/WM). Results: Using linear regression adjusting for cognition-related covariates, we found that higher caffeine intake was associated with better function in overall cognition (p=.018), attention/working memory (p=.002), executive functioning (p=.047), and semantic categorization (p=.026). Interaction analyses of caffeine intake with age were significant for semantic categorization (p=.025), and approached significance for overall cognition (p=.066). This association was driven by the older group (above-median) for whom the association of caffeine intake with semantic categorization (p=.001), attention/working memory (p=.007), executive functioning (p=.005), and overall cognition (p=.002) were significant. In the magnetic resonance imaging subsample, there was an interaction (p=.034) of caffeine intake with age for GM volume; in the older group, higher caffeine intake was associated with greater GM volume (beta=.198, p=.033). Conclusions: Caffeine intake may have a beneficial role in cognitive functioning of elderly adults with T2D, which may be moderated by age. Greater GM volume may be a mechanism underlying the association of higher caffeine intake with better cognitive function.