Insulin nasal spray may slow Alzheimer's

A new study released Monday shows that insulin applied daily through a special nasal spray might be a treatment that slows or stops the progression of Alzheimer’s disease. That’s hopeful news for millions facing the memory-robbing disease, because nothing has been successful at halting its awful progress.

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In the small study, called a Phase II, researchers from the Veterans Affairs Puget Sound Health Care System in Seattle, enrolled 104 people with Alzheimer’s or mild cognitive impairment. The participants were given 20 IU (international units) of insulin, 40 IU of insulint or a saline placebo. Memory, cognition and functional ability were measured before and after treatment. Some of the participants also received lumbar punctures to test cerebrospinal fluid and brain scans before and after treatment.

Adults treated with 20 IU of the insulin nasal spray experienced improved memory and both doses of insulin protected general cognition and ability to function. But the study lasted only four months.

It is critical to note that that if this treatment works in larger studies, it will not be available to patients for a few years, at least.

To make these findings more than just hopeful, researchers must carry out a much larger, longer study, now scheduled to begin next summer. Results from the larger study will not be available for at least 18 months after that.

"Lots of things have looked very promising in the early Phase II studies and we put them into a larger trial and we find nothing," Dr. Laurie Ryan, the clinical trials co-coordinator at the National Institute on Aging, which sponsored the research, warns.

The article is available free at Archives of Neurology

Using insulin, the protein that regulates the body’s metabolism of glucose, for Alzheimer’s might seem unusual. But in recent years, many studies in humans and animals have found that the insulin resistance which is the hallmark of type 2 diabetes plays a critical role in the develop of Alzheimer’s. The brains of people with Alzheimer’s either lack normal levels of insulin or are unable to metabolize the amounts that are present.

However, simply giving a person insulin with the usual method used to treat diabetes would not solve the problem. In fact, it could be very dangerous.

Psychiatrist Dr. Suzanne Craft and her team at the University of Washington and the Puget Sound VA developed a special device that inserts the insulin into the sinus cavities closest to the brain. From there, the protein travels along nerve cells reaching the brain within 15 to 20 minutes.

Using memory tests and brain scans that show the chemical changes typical of Alzheimer’s, the University of Washington team found that two-thirds to three-fourths of the patients taking insulin improved, compared to those taking a placebo, a dummy medication.

“Most medications for Alzheimer’s disease benefit relatively fewer patients,” Craft said.  “So, from that standpoint we were surprised by how many of the participants benefited.”

Recently most of the news about Alzheimer’s has described large, failed trials. But in addition to insulin, other drugs are showing some progress in early trials.

Neurologist Dr. Dennis Selkoe, a pioneering Alzheimer’s researcher at Brigham and Women’s Hospital in Boston wrote recently  “Our field is in a sensitive situation; its promise is palpable, but its potential for disappointment is great.”