Cognitive efficiency declines over time in adults with Type 1 diabetes: effects of micro- and macrovascular complications.

AIMS/HYPOTHESIS: Mild cognitive dysfunction is not uncommon in adults with Type 1 diabetes, but its pathogenesis remains unclear. Previous cross-sectional studies had suggested that microangiopathy might affect brain integrity and lead to "central neuropathy." To assess the relationship between changes in cognitive performance and the incidence of new micro- and macrovascular complications, 103 young and middle-aged adults (mean age: 40 yrs) with childhood-onset Type 1 diabetes were followed over a 7-year period, and were compared to 57 demographically-similar adults without diabetes.
METHODS: All subjects completed a comprehensive battery of neurocognitive tests on two occasions. Diabetic subjects also received repeated medical assessments to diagnose the onset of clinically significant complications.
RESULTS: Relative to control subjects, diabetic adults showed significant declines on measures of psychomotor efficiency; no between-group differences were evident on learning, memory, or problem-solving tasks. The development of proliferative retinopathy and autonomic neuropathy during the follow-up period predicted decline in psychomotor speed (p<0.01), as did incident macrovascular complications (p<0.05), systolic blood pressure at follow-up (p<0.01), and duration of diabetes (p<0.01). CONCLUSION/
INTERPRETATION: This study shows that cognitive efficiency may decline over time in diabetic adults, and that this neurocognitive change may be linked, at least in part, to the occurrence of complications like proliferative retinopathy and elevated blood pressure. Therapeutic interventions that reduce the risk of vascular complications may have a similarly beneficial effect on the brain and reduce the risk of neurocognitive dysfunction in diabetic patients.