Association between handedness and Alzheimer's disease: Results from a large MindCrowd observational study

BackgroundHandedness is tied to the lateralization of brain functions and significantly affects cognitive function and brain activity. Alzheimer's disease (AD) is a progressive brain disorder that leads to declines in memory, thinking skills, and to behavioral changes, which also exhibits lateralized patterns of brain involvement. Understanding the relationship between handedness and AD may provide useful context for interpreting findings in AD research.ObjectivePrevious findings on the relationship between AD and handedness are inconsistent.We used the large MindCrowd dataset, comprising with over 150,000 participants, study the association between AD and handedness.MethodsWe applied logistic regression models to the data with and without adjustment for other covariates to estimate the association between handedness and AD. We also performed similar analyses for samples stratified by ages. We estimated the unadjusted and adjusted odds ratios (ORs) of having AD among left- and mixed-handed participants compared with right- handed participants.ResultsOur results showed that compared with right-handed participants, left- and mixed-handed participants had higher odds of self-reported AD (the overall adjusted OR: 2.08, 95% CI: (1.69, 2.53), p < 0.001)) being larger than that for left-handers (the overall adjusted OR: 1.42, 95% CI: (1.23, 1.64), p < 0.001)). Furthermore, for each age group considered, the estimated adjusted and unadjusted ORs for mixed-handers were consistently greater than that for left-handers; all were greater than 1.0.ConclusionsOur study confirmed that there is a significant association between handedness and AD. Our findings also indicate that mixed-handedness has a stronger association with AD than left-handedness.