Alzheimer’s Disease

Humans are getting better at delaying death. Globally, people on average live to 72, more than five years longer than in 2000. What we haven’t yet figured out is how to beat one of the worst afflictions of aging: Alzheimer’s disease. The brain-shrinking progressive illness has emerged as one of the planet’s biggest public health challenges. More than a century after the tell-tale signs of Alzheimer’s were first seen under a microscope, a few drugs treat the disease’s symptoms, but there are still none that slow, let alone reverse, its progression. Researchers estimate there are 50 million people worldwide living with dementia, with Alzheimer’s the cause in up to 70% of cases. Aging populations mean the number is expected to almost double every 20 years in the absence of medical breakthroughs on preventions or cures.

Drug companies working to combat the underlying disease have long targeted the protein amyloid, which clumps in the brain of Alzheimer’s patients. Researchers don’t know whether amyloid triggers Alzheimer’s or is a minor contributor. Multiple trials of drugs targeting the protein have proved disappointing. The U.S. biotechnology company Biogen Inc. in late 2019 revived one such experimental treatment, after earlier stopping two studies of the medicine based on poor results. The company said additional data showed the infusion, if given for long enough and at high doses, could offer some benefit. Meanwhile, interest has grown in new approaches, especially in those focused on an aberrant protein called tau. As Alzheimer’s progresses, tau spreads through the brain, accumulating in tangles that strangle brain cells. Among the companies testing tau strategies are Eli Lilly, Johnson & Johnson, Biogen, AbbVie and TauRx Pharmaceuticals. The economic costs of dementia care were estimated at $948 billion in 2016, or about 1.2% of the globe’s economic output.