Intranasally Administered Insulin as Neuromodulating Factor and Medication in Treatment of Neuropsychiatric Disorders—Current Findings from Clinical Trials

As a metabolism-controlling peptide, insulin affects activity of almost all tissues in human organisms, including the ones located in the central nervous system. By modifying glucose uptake and processing, as well as inducing anabolic effects, insulin alters functions of various nerve centers. Data from numerous clinical trials prove that such actions can have positive influence on cognitive processes or might be utilized as measures to control appetite, mood, and blood flow, or to prevent unfavorable mental states associated with diminished ability to maintain homeostasis. The intranasal route of administration provides an efficient and targeted delivery method, allowing insulin to be applied directly to different brain regions via the nasal mucosa. Such an approach can also reduce the risk of potential adverse effects associated with this medication, including drops in plasma glucose levels. This review gathers clinical studies’ findings on intranasal insulin’s neuromodulatory properties and its efficacy as additional treatment measure in several neuropsychiatric disease entities.