"Groundbreaking" Alzheimer's trial removes toxic brain plaques
Rsearchers have shown that drug vaccination can remove amyloid plaques from the brains of people with Alzheimer's disease, but unexpectedly found this did not slow down the disease.
The five-year study, funded by the Alzheimer's Research Trust and published in the Lancet, examined 80 patients with mild to moderate dementia who had been immunised with AN1792, a drug which acts to clear amyloid plaques from the brain.
The brains of all people with Alzheimer's disease accumulate amyloid, a protein which clumps together to form toxic plaques. This assumed role of amyloid in the development of Alzheimer's and attempts at its removal have become focal points for dementia research strategies.
The ART study showed immunisation caused a long-term reduction in amyloid in the brain and a variable degree of plaque removal compared with non-immunised control patients.
Contrary to predictions, removal of amyloid plaques did not result in an improvement in cognitive function or survival. Several patients with complete plaque removal deteriorated severely.
The previous consensus among dementia scientists - that removing amyloid plaques is key to defeating Alzheimer's - may now need to be rethought.
Lead researcher Prof Clive Holmes of the University of Southampton said: "Our results suggest that brain deterioration can occur in Alzheimer's despite the removal of plaques. It may be that these toxic plaques trigger the neurodegeneration but don't have an ongoing role. This study opens up numerous avenues for further research."
Rebecca Wood, Chief Executive of the Alzheimer's Research Trust, said: "This is groundbreaking research, and a leap forward in our understanding of Alzheimer's disease. It is disappointing that anti-amyloid treatments did not prevent the disease's progress, but we still need to do more research into whether earlier removal of this initial 'motor' of the disease could slow its progression. These findings underline the need to take a variety of research approaches in a multi-pronged attack on this devastating disease.
"The Alzheimer's Research Trust is funding further research into the toxic nature of amyloids at several UK universities."
www.alzheimers-research.org.uk
- The Alzheimer's Research Trust provides free information on Alzheimer's disease and related dementias: phone 01223 843899 or visit www.alzheimers-research.org.uk.
The paper 'Long-term effects of Aß42 immunisation in Alzheimer's disease: follow-up of a randomised, placebo-controlled phase I trial' by Clive Holmes, Delphine Boche, David Wilkinson, Ghasem Yadegarfar, Vivienne Hopkins, Anthony Bayer, Roy W Jones, Roger Bullock, Seth Love, James W Neal, Elina Zotova, and James A R Nicoll is published in the Lancet, vol. 372, pp216-223, 19th July 2008.
Nature: http://www.nature.com/news/2008/081112/full/456161a.html