What causes Alzheimer's? Study puts leading theory to 'ultimate test'

An idea that has propelled Alzheimer's research for more than 30 years is approaching its day of reckoning.

Scientists are launching a study designed to make or break the hypothesis that Alzheimer's is caused by a sticky substance called beta-amyloid. The study will give an experimental anti-amyloid drug to people as young as 18 who have gene mutations that often cause Alzheimer's to appear in their 30s or 40s.

The study comes after several experimental drugs have to prevent declines in memory and thinking even though they succeeded in removing amyloid from the brains of patients in the early stages