Cerebral complications of diabetes: clinical findings and pathogenetic mechanisms

This review describes the cerebral complications of diabetes mellitus from a neuropsychological, neurophysiological and neuroradiological perspective. In addition, possible pathogenetic mechanisms are discussed. Neuropsychological studies of diabetic patients generally report modest deficits in learning and memory and information processing. Notably, in elderly diabetic patients cognitive deficits may be more prominent. Recent epidemiological studies show that in the elderly diabetes is associated with an increased risk for dementia. Neurophysiological studies show increased latencies of evoked potentials and event-related potentials. Neuroradiological findings are enhanced peripheral and central cerebral atrophy, as well as focal lesions. The pathophysiology of the effects of diabetes on the brain has not been fully elucidated. The putative involvement of cerebral metabolic and microvascular disturbances, similar to those implicated in the pathogenesis of peripheral diabetic neuropathy, is discussed. In addition, the role of repeated hypoglycaemic episodes, cerebrovascular disease and hypertension is addressed. Finally, the potential differential effects of insulin dependent and non-insulin dependent diabetes on the brain are discussed, as well as possible links with brain ageing.