Prospects of intranasal insulin for correction of cognitive impairments, in particular those associated with diabetes mellitus.

Despite the well-studied effect of insulin in peripheral tissues, its role in functioning of the central nervous system is much less understood. The effects of insulin in the brain are extremely diverse: insulin plays an important role in neuron growth and differentiation, affects higher cognitive functions (in particular, the formation of long-term memory), and also has a neuroprotective effect. Both peripheral and central insulin resistance as well as absolute insulin deficiency impairs the functional activity of neurons and neurogenesis. Several studies have investigated intranasal administration of insulin as a potential way for correction of these disorders. The review presents data on abnormalities of the insulin signaling system in the brain in diabetes mellitus, which is accompanied by cognitive dysfunction of varying severity and is associated with the development of neurodegenerative disorders, including Alzheimer's disease. We analyzed the results of studies on the use of intranasal insulin in animal models with diabetes mellitus, healthy volunteers, and patients with cognitive impairments.