medwireNews: Data from the AGES-Reykjavik Study support accumulating cerebral small vessel disease as a contributing factor to the increased risk for depression in people with type 2 diabetes.
“In view of the increased risk of depression in type 2 diabetes, efforts to favorably influence cerebral microvascular function through lifestyle and pharmacological therapy might help to prevent or treat microvascular dysfunction-related depression,” say Lenore Launer (National Institutes of Health, Baltimore, Maryland, USA) and co-researchers.
“Evidence suggests that weight loss and exercise may improve microvascular function and symptoms of depression,” they add.
As reported in Diabetes Care, the team studied 2135 people (58.3% women) without dementia or depression at baseline, aged an average of 74.5 years at baseline, 9.2% of whom had diabetes.
The median score on the 15-item Geriatric Depression Scale (GDS-15) was the same in participants with and without diabetes at baseline, at 1 point, but the 5-year increase was greater in the former than the latter group, at 0.7 versus 0.3. This was statistically significant after accounting for age, sex, education level, alcohol use, smoking history, BMI, hypertension, and the ratio of total to high-density lipoprotein cholesterol.
The study participants all underwent brain magnetic resonance imaging (MRI) at baseline, and those with diabetes had a significantly higher composite score for cerebral small vessel disease than those without diabetes, and they also had a larger 5-year increase in this score, indicating greater cumulative microvascular damage at baseline and during follow up.
In mediation analysis, both the baseline cerebral small vessel disease score and its change during follow-up accounted for a significant proportion of the effect of type 2 diabetes on change in GDS-15 score, after adjusting for other variables.
This is “in accordance with the vascular depression hypothesis,” say the researchers.
They note that a significant effect of diabetes on GDS-15 score remained even after accounting for microvascular disease, and suggest this “may be due to microvascular dysfunction that is not directly captured in the MRI scans in the current study (e.g., microinfarctions, increased blood-brain permeability, and lower cerebral vasoreactivity).”
And the team adds that some people with type 2 diabetes may develop depressive symptoms unrelated to cerebral small vessel disease, with other likely contributors including psychosocial factors, diabetes-related comorbidities, and glucose neurotoxicity.
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