Clearing amyloid beta shows no significant impact on dementia severity

Drugs that target amyloid beta proteins in the brain likely have no clinically meaningful positive effects, while increasing the risk of bleeding and swelling in the brain, a new Cochrane review has found.

People with Alzheimer's disease have high levels of a protein known as amyloid beta in their brains, detectable before symptoms begin, but its role in disease progression is uncertain. Drugs have been developed to remove these proteins from the brain, under the theory that this would prevent or slow disease progression.

The new review examined data from 17 clinical trials with a total of 20,342 participants, all looking at the impact of anti-amyloid drugs on people with mild cognitive impairment or mild dementia due to Alzheimer's disease. Proponents of these drugs have theorised that they would be more effective at these earlier stages before the disease has progressed.

The research found that the absolute effects of anti-amyloid drugs on cognitive decline and dementia severity were absent or trivial, falling well below established thresholds for the minimum clinically important difference.