Daily doses of inhaled insulin preserved the memory of some patients suffering from mild dementia or Alzheimer’s disease and helped them better manage the daily tasks of living, researchers reported.
People with early-stage Alzheimer’s who inhaled insulin twice a day for four months showed improved ability in tasks such as dressing or balancing their checkbooks. There was no improvement on two other measures of mental function for Alzheimer’s, according to the research. Patients getting placebos had a decline in memory and ability to function.
The study of 104 patients, the largest yet to test insulin’s effect on mental abilities of people with dementia, was presented today at the International Conference on Alzheimer’s Disease in Honolulu. Patients used a device called ViaNase, made by privately held Kurve Technology Inc. Impaired ability to make or use insulin has been linked to risk of Alzheimer’s in several studies, said Suzanne Craft, a professor of psychiatry at the University of Washington in Seattle.
“Insulin plays an important role in several aspects of brain function,” Craft, who also serves as director of the geriatric research center of the VA Puget Sound Health Care System, said in a July 9 telephone interview. “If insulin can’t play these roles, the stage is set for the development of Alzheimer’s.”
ViaNase is the only device proven to reach the olfactory region in the brain, said Kurve’s chief executive officer Marc Giroux.
No Low-Blood Sugar
The inhaler allows insulin to make its way to the brain and not to the lungs or limbs, Craft said. For this reason, none of the patients had episodes of low-blood sugar, which happens to some diabetic patients who take too much insulin.
Kurve, maker of the device used in the trial, is seeking a partner to test insulin plus ViaNase for commercial use, Giroux said. Other tests, besides those done by Craft, aren’t ongoing, he said. Kurve, based in Lynnwood, Washington, is in discussions with pharmaceutical companies. Giroux declined to identify them.
Population studies have shown an association between diabetes, a disease that limits people’s ability to make or use insulin, and Alzheimer’s, Craft said. Insulin is known to help maintain the health of the brain’s synapses, which are the points of connection between its cells.
“The idea of using insulin is based on much work in type 2 diabetics that shows that excess insulin in the blood in midlife is associated with later-life Alzheimer’s,” David Knopman, a professor of neurology at the Mayo Clinic in Rochester, Minnesota, said in an e-mail.
The same enzyme that breaks down insulin is involved in the degradation of a protein called amyloid-beta peptide that is thought to be a central player in the development of Alzheimer’s disease, Knopman said.
For these reasons, “the rationale for intranasal insulin is a very reasonable one,” he said. While praising Craft’s work and her current study, he said the four-month duration and relatively small number of subjects made it “too short and too underpowered to draw any strong conclusions.”
In the current study, patients were given inhaled insulin after breakfast and dinner at a total dose of 20 or 40 milligrams a day. Patients in the control group took two sniffs of a placebo each day. The patients and their caregivers, as well as their doctors, were unaware of what each person was given.
The patients were administered tests measuring their memory, use of language and attention. Those who took placebos scored 10 percent lower at the end of the four months than they did at the beginning while the patients taking insulin showed no change.
Caregivers asked to rate the patients’ ability to carry out everyday tasks reported a 10 percent improvement among those who sniffed insulin and a 10 percent decline in those who didn’t. Insulin inhalers didn’t show any improvement on two other measures of Alzheimer’s severity reflecting memory, learning and daily living activity.
Some of the patients also had brain scans and spinal taps so biomarkers in their spinal fluid could be measured. Patients on insulin and in the control group showed differences in the amount of glucose metabolism in the brain and levels of some markers linked to Alzheimer’s.
Craft said her team is now planning a larger, longer study.