Can breaking down brain plaques prevent Alzheimer's?

Amyloid plaques are one of the defining pathologies of Alzheimer’s disease. They are formed by the gradual build-up of a toxic protein called amyloid-beta in brain and are observed later in the disease progression. Therefore, if amyloid plaques are detected in the brain of an individual presenting with dementia then they likely already have Alzheimer’s disease and breaking up the plaques will not prevent them from getting it. Studies in animals have shown that effectively breaking up the amyloid plaques and removing the toxic amyloid-beta from the brain will, however, reduce the disease progression and improve memory (A study from our group demonstrated this using non-invasive scanning ultrasound: Leinenga, G. and Götz, J., Science Translational Medicine , 2015). Unfortunately, the restoration of memory has not been replicated in human clinical trials yet, despite the successful clearance of amyloid-plaques. However, this may be due to other factors, such as the design of the trials, rather than the treatments themselves.  In summary, breaking up amyloid plaques will not prevent Alzheimer’s disease but may slow down its progression.