MRI brain findings in patients with depression and type 2 diabetes – a scoping review

Abstract

Background: The incidence of depression is increased by 200–300% in patients living with diabetes mellitus (DM), with both conditions overlapping in about 10–15% of patients.

Methods: A scoping review was conducted through reputable medical search engines to find articles that mentioned an association between magnetic resonance imaging (MRI) brain findings in patients with concurrent depression and type 2 diabetes mellitus (T2DM).

Results: There were 12 studies found (with 8 790 patients) with publication dates ranging from 2007 until 2020. Most studies utilised a cross-sectional study design with the mean age ranging between 53.8 and 74.5 years. The associations between depression and T2DM varied across the studies, with both comorbidities independently shown to decrease brain size. Two studies suggested that DM decreased the size of the brain (independent of depression), while two other studies suggested that comorbid DM and depression decreased the size of the brain. In addition, decreased myo-inositol concentrations, cerebral hypoperfusion, and abnormal electrical activity of the brain were also observed in those patients with comorbid DM and depression, which differs from patients without these comorbidities.

Conclusion: We recommend that future prospective studies be conducted to establish a consensus on how these comorbidities affect the brain.