After the age of 65, the risk of developing Alzheimer’s disease doubles every 5 years. Now, in line with this, new research finds that the brain’s ability to clear away a toxic protein fragment associated with the disease is much reduced in older people. “We found that people in their 30s typically take about 4 hours to clear half the amyloid beta 42 from the brain. In this new study, we show that at over 80 years old, it takes more than 10 hours,” says Randall J. Bateman, senior author and professor of neurology. It’s long been suspected that these proteins are associated with the disease.