Objective: To examine the relationship of diabetes mellitus to depression, cognition, and structural brain anatomical variables in a 60-64-year-old community-dwelling sample. The authors hypothesized that subjects with Type 2 diabetes are more likely to be depressed, have more brain atrophy, and poorer cognitive function compared with nondiabetic comparison subjects.
Methods: A random sample of 478 subjects aged 60-64 years from a larger community sample were interviewed and underwent physical examinations, assessment of depression, standard cognitive assessments, brain magnetic resonance imaging (MRI) scans, and fasting blood tests. Subjects were considered diabetic if they were on treatment for diabetes or recorded a fasting blood glucose level of greater than 10 mmol/L. The MRI scans were analyzed for brain atrophy, gray matter (GM), white matter (WM), cerebrospinal fluid (CSF), hippocampal, and white matter hyperintensity (WMH) volumes.
Results: MRI data were available for 39 subjects with diabetes and 428 subjects without diabetes. Descriptive analyses showed that subjects with diabetes were more likely to have poor physical health, a higher body mass index, and higher scores of depression and anxiety compared with comparison subjects without diabetes. In multiple regression analyses, diabetes was associated with greater total brain atrophy and larger CSF volume, but did not differ in the WM, GM, and WMH volumes. Diabetes patients performed less well on a task of fine motor dexterity.
Conclusions: Diabetes is related to increased brain atrophy and poor motor function in 60-64 year olds, independent of depression, vascular risk factors, and small vessel disease of the brain.