Whenever you lose connection, take intranasal insulin?

Brain Insulin Resistance at the Crossroads of Metabolic and Cognitive Disorders in Humans

Ever since the brain was identified as an insulin-sensitive organ, evidence has rapidly accumulated that insulin action in the brain produces multiple behavioral and metabolic effects, influencing eating behavior, peripheral metabolism, and cognition. Disturbances in brain insulin action can be observed in obesity and type 2 diabetes (T2D), as well as in aging and dementia. Decreases in insulin sensitivity of central nervous pathways, i.e., brain insulin resistance, may therefore constitute a joint pathological feature of metabolic and cognitive dysfunctions. Modern neuroimaging methods have provided new means of probing brain insulin action, revealing the influence of insulin on both global and regional brain function. In this review, we highlight recent findings on brain insulin action in humans and its impact on metabolism and cognition. Furthermore, we elaborate on the most prominent factors associated with brain insulin resistance, i.e., obesity, T2D, genes, maternal metabolism, normal aging, inflammation, and dementia, and on their roles regarding causes and consequences of brain insulin resistance. We also describe the beneficial effects of enhanced brain insulin signaling on human eating behavior and cognition and discuss potential applications in the treatment of metabolic and cognitive disorders.

Diabetes, Dementia and Hypoglycemia

We are experiencing an epidemic of both diabetes and dementia among older adults in this country. The risk for dementia appears to be increased in patients with diabetes, and patients with dementia and diabetes appear to be at greater risk for severe hypoglycemia. In addition, there may be an increased risk for developing dementia by older patients with diabetes who have had episodes of severe hypoglycemia, although this issue is controversial. In this article, we review the factors that contribute to the increased risk for dementia in older adults with diabetes and outline the complex relationships between hypoglycemia and dementia.