Insulin nasal spray protects against dementia, even in people without diabetes

Insulin may be a vital tool for people with diabetes, but a new study finds it can even help those without blood sugar issues protect themselves against Alzheimer’s disease. Researchers from Beth Israel Deaconess Medical Center (BIDMC) have found that older adults using an insulin nasal spray experienced improved cognition and had a faster walking speed — two markers for dementia. Moreover, the spray had a positive impact on both patients with and without diabetes.

Previous studies have shown that delivering insulin to the brain intranasally (through a nasal spray) improves verbal memory skills. The new study looked at the long-term impact of using intranasal insulin (INI) on the mental and physical health of older individuals.

In a phase 2 randomized controlled clinical trial, the spray helped to increase walking speed, increased blood flow, and decreased plasma insulin in patients with Type 2 diabetes. Additionally, using INI improved decision-making and verbal memory among those without diabetes or those with prediabetes.

“Walking speed is an important clinical predictor of well-being in the elderly that correlates with cognitive decline, hospitalizations, disability and death,” says corresponding author Vera Novak, MD, PhD, of the Department of Neurology at BIDMC and an associate professor of neurology at Harvard Medical School in a media release. “At baseline, participants with diabetes walked slower and had worse cognition than the participants without diabetes, who served as a clinical reference for normal aging population.”

Insulin nasal spray a new early intervention for dementia

Researchers enrolled 223 people in this trial, all between the ages of 50 and 85. Some of the participants had diabetes while others did not. The team assessed each person’s normal walking speeds during various tasks, their memory and executive brain functions, and their mood using a series of cognitive tests.

From there, half of the participants with diabetes (51) and half of the group without the condition (58) began using an insulin nasal spray once a day. The rest of the participants used a placebo spray to serve as a control group.

After 24 weeks, results show those with diabetes taking INI walked faster during and after the study period. They also displayed better cerebral blood flow in the frontal lobe of the brain, as well as lower plasma insulin and insulin resistance. Those without diabetes taking INI enjoyed a sharpened ability to make decisions and a better memory.

“The consistency of the trends in the data showing better performance on walking speed and cognition for INI-treated participants, especially in those with pre-diabetes, carries great implication for potential early intervention using INI in this population to prevent or slow down the progression toward Alzheimer disease’s related dementias,” says Long Ngo, PhD, senior author of the study and co-director of Biostatistics Division of General Medicine at BIDMC.

“With 96 million adult Americans, and increasing number of younger people having pre-diabetes, this finding on the beneficial effect of INI deserves more attention and definitive confirmation in a larger trial.”

Importantly, the team says this treatment did not cause any moderate or serious side-effects. The nasal spray was also safe for participants who also take subcutaneous insulin infusions.

The study is published in the Journal of Neurology.