Cognitive performance in type 1 diabetes patients is associated with cerebral white matter volume

Cognitive performance in type 1 diabetes may be compromised as a result of chronic hyperglycaemia. The aim of this study was to investigate the cognitive functioning of patients with type 1 diabetes (including a subgroup with a microvascular complication) and nondiabetic controls, and to assess the relationship between cognition and cerebral grey and white matter volumes. Twenty-five patients with type 1 diabetes (of whom ten had proliferative retinopathy) and nine nondiabetic controls (matched in terms of sex, age and education) underwent a neuropsychological examination and magnetic resonance imaging of the brain. Fractional brain tissue volumes (tissue volume relative to total intracranial volume) were obtained from each participant. Compared with nondiabetic controls, patients with diabetes performed worse on tests measuring speed of information processing and visuoconstruction; patients with microvascular disease performed worse on the former cognitive domain (p = 0.03), whereas patients without complications performed worse on the latter domain (p = 0.01). Patients with a microvascular complication had a significantly smaller white matter volume than nondiabetic controls (p = 0.04), and smaller white matter volume was associated with worse performance on the domains of speed of information processing and attention and executive function. Patients with diabetes demonstrated several subtle neuropsychological deficits, which were found to be related to white matter volume. Since patients with diabetic retinopathy had a smaller white matter volume, this suggests that cognitive decline is at least partly mediated by microvascular disease. This needs to be addressed in future studies.