People with a specific genetic variation develop Alzheimer's disease at a faster rate than others, U.S. researchers said on Thursday in a finding that may help in the search for drugs to keep the disease at bay.
They said a mutation of a gene that regulates tau -- a protein linked with Alzheimer's -- had a strong impact on the rate at which the disease progresses.
Drugs that interfere with this form of tau may offer a new way to keep the disease from advancing, a team from Washington University in St. Louis reported in the journal PLoS Genetics.
The team has filed for a patent, and it said the Anglo-Swedish drug company AstraZeneca had an option to license it.
"People who carry this genetic marker tend to have higher tau levels at any given stage of the disease than individuals without it," Alison Goate, who worked on the study, said in a statement.
Alzheimer's, the most common form of dementia, is a fatal brain disease in which people gradually lose their memory and their ability to reason and care for themselves.
Goate's team looked at a form of the protein tau that accumulates in the brains of people with Alzheimer's disease and that can also be found in spinal fluid.
Her team looked for single letter changes in the DNA code of genes that affect tau metabolism. They studied more than 800 people and found one version of the gene that regulates tau is linked with more aggressive Alzheimer's disease.
The findings suggest that drugs that interfere with this gene variant might be able to delay the rapid progression of the disease.
"We do know the disease course can last anywhere from five to 20 years. If you could prevent people from declining ... and you could slow that down, then people have a longer period of time when they have good quality of life," Goate said in a telephone interview.
Most drug research in Alzheimer's has focused on blocking another protein called beta amyloid. The new finding "gives us another avenue to think of drug targets in Alzheimer's disease," she said.
Goate and others envision a cocktail of drugs targeting both proteins, much like treatments for heart disease target different pathways of that disease.
No current drugs can permanently alter the progression of Alzheimer's, which affects more than 26 million people globally.
A separate study by a team at the University of California, Berkeley, found that healthy people who took Pfizer's Alzheimer's drug donepezil, sold under the brand Aricept, improved their ability to learn a new skill.
They said healthy people aged 18 to 35 who took the drug as part of a pilot study did much better when they were asked to track dots moving on a computer screen compared with people who took a placebo.
They said the findings, published in the journal Current Biology, could help people with learning problems such as dyslexia.