Diabetes, aging, and cognitive decline

Type 1 diabetes is associated with cognitive changes in children and adults, but the extent to which cognition declines with increasing age, and increasing duration of diabetes, remains poorly understood. This cross-sectional study assessed neuropsychological performance on 200 diabetic and 175 nondiabetic adults, 18–64 years of age, stratified into five age bands. Similar age-related cognitive declines were seen on measures of problem-solving, learning and memory, and psychomotor speed, but it was only on the latter measure that diabetic and nondiabetic subjects differed significantly. The best predictor of psychomotor slowing was the presence of clinically significant biomedical complications, particularly proliferative retinopathy, peripheral neuropathy, and peripheral vascular disease (PVD). It now appears that psychomotor slowing is the fundamental cognitive deficit associated with diabetes mellitus; why other cognitive skills are relatively unaffected remains poorly understood.