November 27, 2013
Single Dose of Intranasal Insulin Improves Cognition in
Older Adults

Boston—Clinical studies indicate that older patients with diabetes develop Alzheimer’s disease at an earlier age and also are more likely to develop vascular dementia than those without diabetes.

It is a complicated problem, but investigators at Beth Israel Deaconess Medical Center in Boston are offering what could be a simple solution.

A small proof-of-concept study published online by the journal Diabetes Care suggests that a single dose of intranasal insulin can help improve cognitive function in patients with diabetes.

“We know that diabetes accelerates brain aging,” explained first author Vera Novak, MD, PhD, an associate professor of neurology at Harvard Medical School. “If we consider that there are more than 45 million people with diabetes in the U.S. alone and that older adults are the fastest growing segment of the diabetes population, we realize what an extremely serious problem we're facing.”

Insulin helps to regulate signaling and connections among neurons and also regulates vascular functions in the brain. Because abundant central insulin receptors are mostly dependent upon insulin transport through the blood-brain barrier, inadequate insulin delivery can affect perfusion and cortical activity in brain regions associated with high-energy demands, such as cognitive networks, according to the study.

Intranasal administration delivers insulin directly to the brain, bypassing the blood-brain barrier and reaching receptors in multiple brain regions within minutes after administration.

With previous reports suggesting improved cognitive function from augmenting cerebral insulin, the researchers tested whether similar effects would be observed in patients with diabetes. Study participants included 15 patients with diabetes and 14 healthy older adults, average age 62, who were administered a single 40-unit dose of insulin or saline in a randomized order on 2 subsequent days. Measurements of brain function were then made using regional perfusion and vasodilatation with 3 Tesla MRI and neuropsychological evaluation of learning and memory.

“We observed in both the healthy subjects and the patients with diabetes that there was an improvement in both verbal learning and visual-spatial learning and memory after they received the insulin,” explained Novak. Imaging tests indicated that the improvements were dependent on the brain’s vascular function.

“Our findings provide preliminary evidence that intranasal insulin administration appears safe in older adults, and does not lead to low sugar levels,” she added. “Intranasal insulin may potentially improve learning and memory in older adults with and without diabetes, through vascular mechanisms. However, larger and longer duration studies are needed to determine whether intranasal insulin may provide long-term benefits for memory in older patients with diabetes.”

U.S. Pharmacist Social Connect