A spray of insulin delivered deep into the nose improved memory and thinking skills in those with early Alzheimer’s disease. Though preliminary, the findings point to possible new avenues for treating a disease that has no effective long-term therapies.
Earlier research has suggested that insulin, delivered nasally so that it can enter the brain, may provide benefits for those with Alzheimer’s. This study used a different form of the hormone, a long-acting man-made form called insulin detemir.
For the study, researchers at Wake Forest Baptist Medical Center studied 60 men and women with early to mid-stage Alzheimer’s disease or mild cognitive impairment, a form of memory loss that can progress to full-blown Alzheimer’s. They divided them into three groups.
One group received nasal insulin spray, at a dose of 40 International Units, every day for 21 days, while those in another group got a lower 20 IU dose. Those in the third group got a placebo spray.
At the end of the three-week period, those getting the higher-dose spray showed improvements in memory skills compared to those getting the lower dose or a dummy spray. Improvements were most pronounced in those who carried the APOE-E4 gene, which raises the risk of developing Alzheimer’s disease. The findings were published in the Journal of Alzheimer’s Disease.
“The study provides preliminary evidence that insulin detemir can provide effective treatment for people diagnosed with mild cognitive impairment and Alzheimer’s-related dementia similar to our previous work with regular insulin,” said Suzanne Craft, professor of gerontology and geriatric medicine at Wake Forest Baptist and lead author of the study. “We are also especially encouraged that we were able to improve memory for adults with MCI who have the APOE-E4 gene, as these patients are notoriously resistant to other therapies and interventions.”
The insulin spray also appeared to be safe, with few side effects reported by patients. Nasal irritation was among the most common side effects.
“Alzheimer’s is a devastating illness for which even small therapeutic gains have the potential to improve quality of life and significantly reduce the overall burden for patients, families and society,” Dr. Craft said. “Future studies are warranted to examine the safety and efficacy of this promising treatment.”
People with diabetes commonly use insulin, a hormone made naturally in the pancreas, in an injectable form by people with diabetes to help keep blood sugar levels under control. This study used a special spray device to deliver insulin deep into the nasal passages, where the fine mist settles and moves directly into the brain along the nerve that transmits odor signals from the nose to the brain.
Others studies have linked diabetes and Alzheimer’s disease. People with diabetes are at increased risk of developing Alzheimer’s disease, and measures that ward off diabetes, like getting regular exercise and eating a Mediterranean-style diet, may keep Alzheimer’s at bay as well.
In another recent study, published in the American Journal of Pathology, scientists found that in mice, a protein resembling beta-amyloid, which builds up in the brains of those with Alzheimer’s disease, also appears to build up in the pancreas in mice that develop diabetes.
Other studies have shown that the brains of people with Alzheimer’s disease have difficulty using common sugars as an energy source. An insulin spray, the researchers hoped, might aid memory by boosting the metabolism of sugars in the brain.
The nasal form of the drug, and the device used to deliver it nasally, are only available in research labs. Nobody is suggesting that anyone go out and inhale insulin, and doctors do not prescribe it.
But the study results, though modest, support further investigation of the therapeutic value of insulin as a treatment for brain ailments like Alzheimer’s, Dr. Craft said.
Sources: Claxton A, Baker LD, Hanson A, et al: “Long-Acting Intranasal Insulin Detemir Improves Cognition for Adults with Mild Cognitive Impairment or Early-Stage Alzheimer’s Disease Dementia.” The Journal of Alzheimers Disease, doi: 10.3233/JAD-141791, Volume 44, No. 3, February 2015.
Oskarsson M, Paulsson J, Schultz S, et al: In vivo Seeding and Cross-seeding of Localized Amyloidosis: A Molecular Link between Type 2 Diabetes and Alzheimer Disease. The American Journal of Pathology. 2015.