En español | A unique treatment that uses insulin in the form of a nasal spray shows promise for boosting memory in men and women with Alzheimer's disease, according to a study released in the Sept. 12 online edition of the Archives of Neurology.
In a four-month study, participants with either mild or moderate Alzheimer's disease or mild cognitive impairment who received a low dose of insulin fared better on memory tests than those who received a placebo.
Experts say that these encouraging results should lead to a larger clinical trial to confirm effectiveness of the treatment.
Insulin's role in Alzheimer's
Researchers selected 104 men and women for the study. All had either mild to moderate Alzheimer's or mild cognitive impairment, a condition that increases the risk of developing Alzheimer's, especially when memory is affected. The participants were divided into three groups. Using a nasal spray, each group received twice-daily doses of either lower or higher doses of insulin or a placebo.
The study found that men and women who used the lower dose of insulin nasal spray tended to score better on memory tests than those who used the placebo. No improvement was seen in those receiving the higher insulin dose. Both groups receiving insulin preserved their level of daily functioning, according to reports from their caregivers, while participants in the placebo group showed an overall decline in function. Few side effects occurred among those treated with the insulin spray, other than occasional light-headedness and dizziness or stuffy nose.
The brain needs insulin
Over the past 10 years scientists have come to learn that insulin plays an important role in the brain, says clinical neuroscientist Suzanne Craft, of the Veterans Affairs Puget Sound Health Care System and the University of Washington School of Medicine. It helps the brain form memories, allows brain cells to communicate with one another and manages levels of brain chemicals.
All cells, including those that make up the brain, use glucose for energy. The hormone insulin makes it possible for glucose, aka blood sugar, to enter cells, enabling them to work properly. With age, however, many people develop a problem called insulin resistance, a condition in which the body and the brain do not use insulin effectively.
If glucose cannot enter brain cells, the cells won't carry out their tasks related to memory and thinking. "This sets the stage for problems in brain function that may develop into conditions like Alzheimer's disease," says Craft, lead author of the study. She and her colleagues set out to determine whether providing insulin directly to the brain could improve the cell's ability to use insulin.