Alzheimer’s study finds signs years before symptoms
Thursday, 19 July 2012 13:28. RESEARCH SHOWING Alzheimer’s-related changes begin to develop 25 years before symptoms such as memory loss manifest themselves has the potential to have a crucial impact on future treatment, an Irish advocacy body has said. The study, published in the New England Journal of Medicine, shows a timeline of changes in spinal fluid, brain size, the appearance of brain plaques and other factors that precede the onset of Alzheimer’s in people who are genetically disposed to developing the brain-wasting disease.
Plaques and “tangles” – a build-up of proteins in the brain – gradually damage and eventually destroy nerve cells, causing the characteristic loss of memory, reason and sometimes language. “It’s really the first report that we have in living people of these changes,” said Dr Randall Bateman of Washington University School of Medicine in St Louis, Missouri, who helped lead the study. Current drugs for Alzheimer’s only treat symptoms and none has yet been able to keep the disease from progressing.
Scientists have been searching for ways to test treatments at an earlier stage. The study by the team at Washington University focused on families who are genetically predisposed to develop the disease at an early age. “On average, patients with this form get Alzheimer’s disease by 45,” Dr Bateman said. People in these families have a 50 per cent chance of inheriting one of three genes that cause early Alzheimer’s and most develop symptoms around the same time as their affected parent.
Dr Bateman followed the progress of 129 individuals and used family histories to estimate when study subjects were likely to develop Alzheimer’s symptoms. They developed a timeline of changes leading up to the memory loss and declines in thinking skills. The first of these changes, a drop in the level of a protein known as amyloid, can be detected in spinal fluid 25 years before the disease is expected to develop.
At 15 years before onset, clumps of an Alzheimer’s-related protein called beta amyloid become visible on brain scans. Other scans show shrinkage of brain structures, and levels of a toxic protein start to rise in spinal fluid. At 10 years before onset, the brain becomes less adept at using glucose and some slippage in certain kinds of memory skills can be detected.
The World Health Organization estimates some 35.6 million people worldwide are living with dementia. It affects almost 44,000 people in Ireland and Alzheimer’s accounts for two-thirds of all cases. Alzheimer Society of Ireland chief executive Maurice O’Connell said the research had the potential to have “a crucial impact” on future treatments and diagnosis of Alzheimer’s and dementia.
“However it must be noted that this research focuses solely on dominantly inherited Alzheimer’s disease so more research will be needed in order to see whether there are similar changes in those who develop non-hereditary Alzheimer’s disease,” he said. “We welcome all research into the area of early intervention in the Alzheimer Society of Ireland and see it as a crucial step, along with the development of a national dementia strategy in Ireland, for providing the best possible services and care for people with dementia.”