Dr. Suzanne Craft and colleagues at the Veterans Administration's Puget Sound Health Care System in Seattle tested insulin spray on people without diabetes who had been diagnosed with mild to moderate Alzheimer's disease. Thirty-six inhaled 20 milligrams of insulin twice a day for four months, 38 inhaled 40 milligrams twice a day and 30 were given a saline solution.
Previous studies found that low brain levels of insulin -- the main hormone that turns sugar in the bloodstream into energy for cells -- could contribute to Alzheimer's, said Craft, the study leader.
Studies have shown those with diabetes and pre-diabetes are more at risk of developing Alzheimer's, and autopsies showed diabetics whose blood sugar was well-managed had fewer of the brain tangles and plaques that are a part of Alzheimer's.
The study, published online in the journal Archives of Neurology, found after two months of treatment, those treated with 20 mg of insulin had improved performance on a memory test, thinking skills and functional ability; while patients who got the higher dose of insulin had no change in their memory abilities and those who got the placebo saw a decline.
However, the researchers emphasize this is a preliminary finding that needs more research and no one should try this treatment because it could be life-threatening.