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BODY MASS INDEX AND RISK OF DEMENTIA
Abstract
Background and Aims
Midlife obesity and underweight in the elderly have been associated with a high risk of dementia. However, the association between body mass (BMI) and risk of dementia depends on the type of dementia investigated. Whether there is a causal association between BMI and the vascular part of dementia called “non-Alzheimer dementia” remains unknown. We aimed to investigate the association between BMI and risk of “non-Alzheimer dementia”, Alzheimer’s disease, and all-cause dementia.
Methods
In a prospective cohort of the Danish general population including 95,000 individuals we investigated the observational and genetically determined association between BMI and risk of “non-Alzheimer dementia”, Alzheimer’s disease, and all-cause dementia. For the genetic analyses we created a weighted allele score and divided it into four groups from lowest to highest BMI.
Results
The observational association between BMI and risk of “non-Alzheimer dementia” and all-cause dementia was u-shaped with nadir at a BMI of 26 kg/m2. For Alzheimer’s disease the association was linear with low BMI associated with high risk. Comparing the group with the lowest genetically determined BMI to the group with the highest genetically determined BMI the hazard ratio (95% confidence interval) was 1.22 (1.01- 1.47) for “non-Alzheimer dementia”, 1.04 (0.90-1.20) for Alzheimer’s disease, and 1.10 (0.98-1.23) for all-cause dementia.
Conclusions
Genetically determined high BMI is associated with high risk of the vascular part of dementia in the general population. BMI is thus a potentially modifiable risk factor for dementia that could be targeted in the strive to prevent this devastating disease.