Cognitive functioning and structural brain abnormalities in people with Type 2 diabetes mellitus

• Published in: Diabetic medicine 2018-12, Vol.35 (12), p.1663-1670
• Main Authors: Mankovsky, B., Zherdova, N., Berg, E., Biessels, G.‐J., Bresser, J.
• Format: Article
• Language: English
• Subjects: Aged; Brain - diagnostic imaging; Brain - pathology; Brain - physiology; Brain Diseases, Metabolic - diagnosis; Brain Diseases, Metabolic - etiology; Brain Diseases, Metabolic - pathology; Case-Control Studies; Cognition & reasoning; Cognition - physiology; Cognition Disorders - diagnosis; Cognition Disorders - etiology; Cognition Disorders - pathology; Cognitive ability; Diabetes; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 2 - complications; Diabetes Mellitus, Type 2 - diagnosis; Diabetes Mellitus, Type 2 - pathology; Diabetes Mellitus, Type 2 - psychology; Executive function; Female; Glycated Hemoglobin A - metabolism; Humans; Magnetic Resonance Imaging; Male; Memory; Middle Aged; Neuroimaging - methods; Neurological disorders; Neuropsychological Tests; Organ Size; Substantia alba; Vascular diseases
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/dme.13800

Aims Type 2 diabetes mellitus is associated with cognitive dysfunction, but the underlying structural brain correlates are uncertain. This study examined the association between cognitive functioning and structural brain abnormalities in people with long‐standing Type 2 diabetes. Methods Ninety‐three people with Type 2 diabetes (age 62.3 ± 5.4 years, diabetes duration 9.7 ± 6.7 years; HbA1c 65 ± 10 mmol/mol, 8.1 ± 1.3%) were included. Cognitive functioning was assessed by a test battery covering the domains memory, processing speed and executive functioning. Brain tissue volumes and white matter hyperintensity volumes were automatically determined on MRI. Linear regression analyses were performed adjusted for age, sex and education. Results In people with Type 2 diabetes, increased white matter hyperintensity volume was associated with decreased processing speed [regression B coefficient = −0.22 (−0.38 to −0.06), P = 0.009], but not with memory or executive function (P > 0.05). Brain tissue volumes were not significantly related to cognitive functioning (P > 0.05). Conclusions In people with long‐standing, less strictly controlled Type 2 diabetes, white matter hyperintensities volumes were associated with decreased processing speed. This suggests that cerebral small vessel disease is an underlying disease mechanism of cognitive dysfunction in these individuals. What's new? Type 2 diabetes mellitus is associated with cognitive dysfunction and an increased risk of dementia, but the underlying mechanisms are uncertain. We have shown that white matter hyperintensity volumes on MRI are associated with decreased processing speed in people with Type 2 diabetes from a low‐ to medium‐income country. The effect sizes of brain structure to cognition relationships were relatively small and lost significance after applying strict correction for multiple comparisons. Future studies on structural brain correlates in Type 2 diabetes should take this into account. Higher blood pressure and worse kidney function, but not measures of glycaemia, were related to worse cognition, but not to more abnormal brain volumes. A clinical implication is that vascular factors may provide leads for preventing cognitive decline in people with Type 2 diabetes.