Worldwide, about 44 million people have dementia. Type 2 diabetes is associated with a 50% increased risk of developing dementia. In this this population-based longitudinal study, the researchers examined data collected from two cohorts of dementia-free elderly adults living in Stockholm, Sweden.

The researchers also examined the brain structure of a subsample of the second cohort using magnetic resonance imaging (MRI). The researchers found that the HHEX_23-AA genotype interacted with diabetes to substantially increase the risk of dementia/Alzheimer disease. MRI data showed that, HHEX_23-AA carriers with diabetes had structural brain changes compared to HHEX_23-GG carriers without diabetes, even though they were all free of dementia at the time. Importantly, however, these findings highlight the need to control diabetes to prevent the development of Alzheimer disease and dementia, particularly among HHEX_23-AA Carriers.

Xu WL, Pedersen NL, Keller L, Kalpouzos G, Wang HX, Graff C, et al. HHEX_23 AA genotype exacerbates effect of diabetes on dementia and Alzheimer disease: a population-based longitudinal study. PLoS Med. 2015;12(7):e1001853