Diabetes Mellitus Is a Risk Factor for Vascular Dementia, but Not for Alzheimer's Disease: A Population-Based Study of the Oldest Old
|Linda B. Hassing a1a2, Boo Johansson a1a2, Sven E. Nilsson a2, Stig Berg a2, Nancy L. Pedersen a3, Margaret Gatz a4 and Gerald McClearn a5|
a1 Department of Psychology, Göteborg University, Göteborg, Sweden
a2 Institute of Gerontology, School of Health Sciences, Jönköping, Sweden
a3 Department of Medical Epidemiology, Karolinska Institute, Stockholm, Sweden
a4 Department of Psychology, University of Southern California, Los Angeles, California, US
a5 Center for Developmental and Health Genetics, Pennsylvania State University, University Park, Pennsylvania, US.
Background: The purpose of this study was to examine if Type 2 diabetes mellitus is a risk factor for dementia in very old age, specifically for Alzheimer's disease (AD) and vascular dementia (VaD). Methods: We evaluated the risk of dementia in relation to Type 2 diabetes using a population-based sample of 702 individuals aged 80 years and older (mean age 83 years). A total of 187 persons received a dementia diagnosis. Thirty-one individuals had a diabetes diagnosis prior to onset of the dementia. Results: Cox proportional hazard analyses, adjusted for age, gender, education, smoking habits, and circulatory diseases, indicated an elevated risk to develop VaD (relative risk = 2.54, 95% confidence interval 1.35–4.78) in individuals with diabetes mellitus. No association was found between diabetes and AD. Conclusion: Type 2 diabetes is selectively related to the different subtypes of dementia. There is no increased risk of AD but more than a twofold risk of VaD in persons with diabetes.
Key Words: Type 2 diabetes mellitus; Alzheimer's disease; vascular dementia; population-based study; very old.