Researchers believe the protein beta-amyloid is a primary driver of Alzheimer’s disease. Beta-amyloid plays an essential role in neural growth and repair. However it can become corrupted as you get older. This leads to the breakdown of nerve cells. Studies show that people in their 30’s take about four hours to clear half the beta-amyloid amount in their brains. For people 80 years old and older, the amount of time jumps to ten hours.