From Nature magazine
Of the top ten leading causes of death in the United States, Alzheimer's disease--which ranks sixth--is particularly devastating in that there is no cure, no way to prevent it and no proven way to slow its progression. And with at least 11 million Americans expected to have the disease by the middle of the century--boosting the annual costs of health care to more than $1 trillion--the U.S. government is anxiously looking to researchers to improve the prognosis.
Last week, the government set out how it planned to spend a $50-million top-up to this year's funding for the National Institutes of Health (NIH) in Bethesda, Md., announced in February as part of a bid to "prevent and effectively treat Alzheimer's disease by 2025".
The money adds to the $448 million that the NIH was allocated to spend on the disease this year, and roughly half of it is already being used by scientists funded by the National Human Genome Research Institute and the National Institute on Aging. They are preparing to conduct whole-genome and whole-exome studies to discover mutations that may predispose someone to the disease or protect against it. The scientists are assembling a bank of thousands of DNA samples from patients and other people whose DNA could be informative--such as elderly individuals who carry predisposing mutations but show no sign of the disease. The first results from the effort are expected as early the end of this year.
Of the remaining money, $4 million will fund Alzheimer's-oriented grants to small businesses, and $2 million will be used to help generate model human Alzheimer's cells from induced pluripotent stem cells. The rest will be devoted to two groundbreaking clinical trials, one of which builds on the fact that Alzheimer's begins to attack the brain 10-15 years before symptoms appear--a conclusion confirmed by new imaging tools that allow the disease to be monitored in living people.
This trial will receive $16 million, and is the first attempt to avert the onset of Alzheimer's by treating people who have not yet developed symptoms. It is a five-year study using an antibody called crenezumab, made by Genentech of South San Francisco, California. Already in phase II trials in patients with mild-to-moderate symptoms, the drug is thought to work by binding to fragments of amyloid-beta--insoluble, neuron-damaging peptides that aggregate in the brains of those with Alzheimer's--both neutralizing it and making it easier for immune cells in the brain to eliminate it (see 'Neural defenders'). The Banner Alzheimer's Institute (BAI) in Phoenix, Ariz., together with a team at the University of Antioquia in Medellin, Colombia, will test the drug against a placebo in 300 symptom-free people, two-thirds of whom carry a rare genetic mutation that makes them certain to get the disease. Mild cognitive impairment sets in at a median age of 44 in people carrying the mutation, and full-blown dementia at 49, decades earlier than is common with the more typical sporadic form of the disease.
Most of the participants will come from a well-studied extended Colombian family living in Medellin and its surrounding rural areas that is estimated to have 5,000 members. They range from educated urbanites to humble farmers, all descendants of the same eighteenth-century founder. Although most do not know, and do not wish to know, their genetic status, about 1,500 are estimated to carry the mutation.
"You cannot meet these families and not be converted to their cause. It's heartbreaking," says Eric Reiman, one of the trial's three leaders and executive director of the BAI.
The other trial will receive $7.9 million and is being led by Suzanne Craft, a neuropsychologist at the University of Washington and associate director of geriatric research at the VA Puget Sound Health Care System, both in Seattle. It will test an intranasal insulin spray against placebo in people with mild cognitive impairment or early Alzheimer's. Insulin receptors are abundant in synapses in brain regions that are important for memory and cognition, and in Alzheimer's, amyloid-beta can knock out the receptors and disrupt memory formation. Flooding rat brain cells with insulin has been found to block the fragments and protect the receptors (F. G. De Felice et al. Proc. Natl Acad. Sci. USA 106, 1971-1976; 2009). When Craft tried the strategy in humans by giving intranasal insulin to people with mild cognitive impairment or early Alzheimer's, the results were impressive: about three-quarters remained stable or improved cognitively over the four months of treatment, Craft says.