The plan is part of the National Alzheimer's Project Act, signed into law last year, which aims to develop new ways to prevent and treat Alzheimer's by 2025. About 5.4 million Americans have the disease now, according to the Centers for Disease and Prevention in Atlanta.
The goal, to develop new treatments by 2025, faces tough challenges, said Ronald Petersen, director of Alzheimer's disease research at the Mayo Clinic in Rochester, Minn.
Researchers are unsure what sets off the disease process that leads to dementia or even whether the protein tangles in the brain - a hallmark of the disease - are a cause or simply a by-product of the condition.
Alzheimer's destroys brain cells, making it difficult for patients to think, remember and function. Markers of brain-cell death include amyloid plaques and tau tangles that can begin in the brain 10 to 20 years before symptoms occur.
Researchers suspected a link between Alzheimer's disease and diabetes after scientists found excess insulin in the blood was associated with the diseases later in life. Insulin is known to help maintain the brain's synapses.
A 2010 study found that people with early stages of the disease who used an insulin inhaler made by Kurve Technology Inc. twice a day showed improved ability to carry out daily tasks such as dressing or balancing their checkbooks.
Previous studies show diabetics have an elevated risk of developing Alzheimer's disease and mild cognitive impairment, a potential precursor to the most common form of dementia in the elderly. Catching the disease early, when memory and language deficits first develop, may improve the odds of treating or preventing the condition.
Efforts to capitalize on the link have yielded mixed results. A daily dose of inhaled insulin improved the memory of patients with early-stage Alzheimer's and helped them manage routine tasks like getting dressed. The approach did not improve other measures of mental function. GlaxoSmithKline PLC's Avandia, once the biggest-selling diabetes drug, failed to benefit Alzheimer's disease patients in a 2009 study.
As part of the federal initiative, people who are genetically guaranteed to suffer from the disease years from now will for the first time be given a drug intended to stop them from developing it.
Most of the study's participants will be drawn from an extended family of 5,000 people who live in Medellin, Colombia, and remote mountain villages outside that city. Those who possess a specific genetic mutation begin showing cognitive impairment around age 45, and full-blown dementia around age 51. The 300 family members who participate in the initial phase of the trial will be years away from developing symptoms.
The $100 million study will run for five years, but results on sophisticated tests may indicate in as little as two years whether the drug is helping to delay memory decline or brain changes. The trial will be financed with $16 million from the National Institutes of Health, about $15 million from private donors through the Banner Institute and $65 million from Genentech, the drug's U.S. manufacturer.
This article contains information from Inquirer wire services.