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

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.