Cognitive Dysfunctions in Type 1 Diabetes

Abstract

The review summarizes key studies assessing epidemiology, mechanisms, and consequences of cognitive dysfunction (CD) in type 1 diabetes (DM1). Evidence Synthesis: In a number of studies, the severity of CD in DM1 was affected by the age of onset and diabetes duration, the presence of proliferative retinopathy and autonomic neuropathy. Diabetes-related CD has been observed not only in adults but also in children and adolescents. Most neuroimaging studies in DM1 did not show any differences in whole brain volumes, however, they did reveal selective deficits in grey matter volume or density within the frontal, posterior and temporal cortex, subcortical grey matter. Studies of middle-aged adults with long-standing DM1 using diffusion tensor imaging have demonstrated partial lesions of white matter and decreased fractional anisotropy in posterior brain regions. The mechanisms underlying diabetes-related CD are very complex and include factors related to diabetes per se and to diabetes-related cardiovascular disease and microvascular dysfunction: chronic hyperglycemia, hypoglycemia, macro- and microvascular disease, increased expression of inflammatory cytokines. The above mechanisms may contribute to the development and progression of both vascular dementia and Alzheimer disease. Conclusions: Higher rates of CD and its faster progression in DM1 can be explained by both the direct effects of altered glucose metabolism on the brain and diabetes-related cardiovascular disease. Since the presence and progression of CD significantly worsens the quality of life of diabetic patients, further multidisciplinary studies based on the recent progress in both neuroimaging and type 1 diabetes management are warranted to tackle this problem.