Association between diabetes and causes of dementia: Evidence from a clinicopathological study

Maria Niures Pimentel dos Santos Matioli, Claudia Kimie Suemoto, Roberta Diehl Rodriguez, Daniela Souza Farias, Magnólia Moreira da Silva, Renata Elaine Paraizo Leite, Renata Eloah Lucena Ferretti-Rebustini, Carlos Augusto Pasqualucci, Wilson Jacob, Lea Tenenholz Grinberg, Ricardo Nitrini

Diabetes mellitus is a risk factor for dementia, especially for vascular dementia (VaD), but there is no consensus on diabetes as a risk factor for Alzheimer's disease (AD) and other causes of dementia. To explore the association between diabetes and the neuropathological etiology of dementia in a large autopsy study. Data were collected from the participants of the Brain Bank of the Brazilian Aging Brain Study Group between 2004 and 2015. Diagnosis of diabetes was reported by the deceased's next-of-kin. Clinical dementia was established when CDR ≥ 1 and IQCODE > 3.41. Dementia etiology was determined by neuropathological examination using immunohistochemistry. The association of diabetes with odds of dementia was investigated using multivariate logistic regression. We included 1,037 subjects and diabetes was present in 279 participants (27%). The prevalence of dementia diagnosis was similar in diabetics (29%) and non-diabetics (27%). We found no association between diabetes and dementia (OR = 1.22; 95%CI = 0.81-1.82; p = 0.34) on the multivariate analysis. AD was the main cause of dementia in both groups, while VaD was the second-most-frequent cause in diabetics. Other mixed dementia was the second-most-common cause of dementia and more frequent among non-diabetics (p = 0.03). Diabetes was not associated with dementia in this large clinicopathological study.