Written by Faith Anderson on September 15, 2011
Insulin is a metabolic hormone commonly used in the treatment of diabetes, a disease in which the hormone is either insufficiently produced or poorly used by the body’s organs. However, recent studies have indicated that people with diabetes have an increased risk of developing Alzheimer’s disease, a debilitating neurological disorder characterized by significant memory loss and dementia. Furthermore, autopsies have shown that diabetics whose condition was well-managed with insulin had fewer of the markers in the brain associated with Alzheimer’s. Animal studies have also shown that insulin deficiency in the brain may be a key factor in the progression of Alzheimer’s.
Alzheimer’s Study Sees Improvement in Patients Treated with Insulin
The study, although only preliminary, suggests that a safe, cheap and simple measure that boosts flagging metabolism in critical areas of the brain could stave off or possibly reverse the progression of the early stages of Alzheimer’s disease. Researchers from the Veterans Administration’s Puget Sound Health Care System in Washington decided to test insulin on people without diabetes who had been diagnosed with mild to moderate Alzheimer’s or amnestic mild cognitive impairment, a condition characterized by increased forgetfulness that often progresses to dementia.
The study involved 104 participants divided into three groups: 36 inhaled 20 milligrams of insulin twice a day for four months, 38 inhaled 40 mg twice a day, and 30 were given a saline solution. After two months of treatment, those treated with 20 mg of insulin had improved performance on a memory test. The benefits continued after four months of treatment, and were still evident two months after the insulin treatment was discontinued. Patients who received the higher dose of insulin had no change in memory abilities, and those who got the placebo saw a decline. While the differences between participants taking insulin and those on the placebo were “small in absolute terms,” they were significant enough that they were unlikely to be the result of chance, according to generally accepted research standards.
Further Research Needed, But Results are Promising
Researchers believe the insulin treatment may minimize the brain tangles and plaques that are linked to Alzheimer’s disease. In fact, a subset of study participants underwent additional measurements, and researchers found that there were fewer protein tangles, amyloid plaque deposits and other physiological markers of the neurological disease in those whose memory improved most on the insulin treatment, compared to those who had weak responses or were on the placebo. Unfortunately, two months after the treatment was terminated, caregivers of subjects in all three groups noted similar declines in overall daily function.
According to Dr. Jacobo Mintzer, an Alzheimer’s expert at the Medical University of South Carolina in Charleston who was not involved in the insulin study, this research is a “new way of thinking” about treating dementia. “As a clinician, I would not tell my patients to get their hopes up,” Mintzer said, “But as a scientist, I always get very encouraged when the paradigm shifts.” According to neuropsychologist, Laurie Ryan, who directs clinical trials involving dementia at the National Institute on Aging, it will take a larger study involving more patients over a longer period of time to figure out whether nasally administered insulin merely slows the symptoms of Alzheimer’s or reverses it. In the meantime Ryan says, “A safe, easy delivery system – those are the things we’d love to see for any kind of treatment for Alzheimer’s disease.”