The structural correlates of impaired cognition in type 2 diabetes are unclear. The present study compared cognition and brain magnetic resonance imaging (MRI) between type 2 diabetic patients and nondiabetic control subjects and assessed the relationship between cognition and MRI findings and blood pressure and metabolic control. The study included 113 patients and 51 control subjects. Brain MRI scans were rated for white matter lesions (WMLs), cortical and subcortical atrophy, and infarcts. Neuropsychological test scores were divided into five cognitive domains and expressed as standardized Z values. Type 2 diabetes was associated with deep WMLs (P ‫؍‬ 0.02), cortical (P < 0.001) and subcortical (P < 0.05) atrophy, (silent) infarcts (P ‫؍‬ 0.06), and impaired cognitive performance (attention and executive function, information-processing speed, and memory, all P < 0.05). Adjustment for hypertension did not affect the results. Within the type 2 diabetic group, cognitive function was inversely related with WMLs, atrophy, and the presence of infarcts (adjusted for age, sex, and estimated IQ), and there was a modest association with HbA 1c and diabetes duration. This association was strongest for age, even more so than in control subjects. We conclude that cognitive impairments in patients with type 2 diabetes are not only associated with subcortical ischemic changes in the brain, but also with increased brain atrophy. Diabetes

Aims/hypothesis The determinants of cerebral complications of type 2 diabetes are unclear. The present study aimed to identify metabolic and vascular factors that are associated with impaired cognitive performance and abnormalities on brain MRI in patients with type 2 diabetes. Methods The study included 122 patients and 56 controls. Neuropsychological test scores were divided into five cognitive domains and expressed as standardised z values. Brain MRI scans were rated for white matter lesions (WML), cortical and subcortical atrophy, and infarcts. Data on glucose metabolism, vascular risk factors and micro-and macrovascular disease were collected.Results Patients with type 2 diabetes had more cortical (p< 0.001) and subcortical (p<0.01) atrophy and deep WML (p= 0.02) than the control group and their cognitive performance was worse. In multivariate regression analyses within the type 2 diabetes group, hypertension (p<0.05) and a history of vascular events (p<0.01) were associated with worse cognitive performance, while statin use was associated (p<0.05) with better performance. Retinopathy and brain infarcts on MRI were associated with more severe cortical atrophy (both p<0.01) and statin use with less atrophy (p<0.05). Insulin level and brain infarcts were associated with more severe WML and statin use with less severe WML (all p<0.05). Conclusions/interpretation Type 2 diabetes is associated with modest impairments in cognition, as well as atrophy and vascular lesions on MRI. This 'diabetic encephalopathy' is a multifactorial condition, for which atherosclerotic (macroangiopathic) vascular disease is an important determinant. Chronic hyperglycaemia, hyperinsulinaemia and hypertension may play additional roles.

Type 2 diabetes mellitus (DM2) is a common metabolic disorder. DM2 is associated with cognitive impairments, and with depressive symptoms, which occur in about one third of patients. In the current study we compared the cognitive profile and psychological well-being of 119 patients with DM2 (mean age: 66 +/- 6; mean duration: 9 +/- 6 years) with 55 age and education matched-control participants. Groups were compared on cognitive performance in five major cognitive domains, psychological wellbeing [assessed by Symptom Checklist (SCL)-90-R and the Beck Depression Inventory (BDI-II)] and abnormalities on brain MRI. We hypothesized an interrelationship between cognition, MRI abnormalities, and psychological well-being. DM2 patients performed significantly worse than controls on cognitive tasks, especially on tasks that required more mental efficiency, although the differences were modest (effect sizes Cohen d < .6). We speculate that DM2 patients have a diminished ability to efficiently process unstructured information. Patients with DM2 had significantly higher scores on the SCL-90-R (p < .001) and on the BDI-II (p < .001) and worse MRI ratings than controls, but psychological distress did not correlate with cognition, MRI ratings or biomedical characteristics. Contrary to our hypothesis, cognitive disturbances and psychological distress thus seem independent symptoms of the same disease.

Aim/hypothesis Underlying mechanisms for decreased cognitive functioning in patients with type 2 diabetes are unclear. In the general population, cerebral hypoperfusion is a risk factor for cognitive dysfunction and dementia.

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