Neurobehavioral complications of type I diabetes. Examination of possible risk factors.

There is increasing interest in the possibility that diabetes mellitus may be associated with a series of neurobehavioral, or neuropsychological, changes; i.e., learning, memory, problem solving, mental and motor speed, and eye-hand coordination may sometimes be disrupted in diabetic children and adults, and this disruption may be a consequence of certain disease-related variables. To date, four neurobehavioral risk factors have been identified. For children and adolescents, the most potent risk factors appear to be age at diagnosis and the occurrence of schoolroom-related problems. Children who develop diabetes early in life are more likely to show serious cognitive impairments on virtually all measures. In addition, diabetic children with school attendance problems tend to score lower than expected on verbal IQ tests and school achievement tests. For adults, the most carefully studied risk factor is degree of metabolic control. Adults in poor control are far more likely to manifest subtle changes on measures of mental efficiency. This may be particularly evident on tasks that require the development and deployment of sophisticated information-processing strategies. A fourth variable--severe episodes of hypoglycemia--is known to disrupt functioning in diabetic subjects of any age, although it has not yet been studied systematically in large-scale studies. Indeed, because virtually all extant studies have been based on limited neurobehavioral and biomedical assessments of relatively few volunteer subjects, this list of risk factors must be considered tentative at best.