Alzheimer's could be spotted in people 20 years before the first symptoms appear, scientists have found.
Researchers at Sweden’s Karolinska Institute and the Uppsala University discovered that inflammation occurs in the brain decades before the condition shows any other signs.
It means that in future doctors could predict which people will go on to develop Alzheimer’s disease when there is still time to make lifestyle changes or take drugs to slow down the condition.
Treatments which can put the brakes on dementia are currently undergoing trials and could be available within a few years, so tests which can pick up the disease early are likely to be crucial in future care.
Researchers followed families who were known to carry genes which made them more susceptible to Alzheimer's. Most of them will develop the condition by the time they are in their mid-50s.
All participants underwent memory tests and brain scans.
The mutation carriers were found to have inflammatory changes – known as astrocyte activation - almost twenty years before the estimated debut of memory problems. Astrocytes are a type of brain cell which increase following an injury to aid repair.
The researchers also found a crucial window, around seventeen years before symptoms develop, where the sticky amyloid plaques which cause dementia began to increase.
“Inflammatory changes in the form of higher levels of brain astrocytes are thought to be a very early indicator of disease onset,” explains principal investigator Professor Agneta Nordberg at the Department of Neurobiology, Care Sciences and Society, Centre for Alzheimer Research at the Karolinska Institute.
“Astrocyte activation peaks roughly twenty years before the expected symptoms and then goes into decline, in contrast to the accumulation of amyloid plaques, which increases constantly over time until clinical symptoms show.”
There are currently 850,000 people living with dementia in Britain, most of whom have Alzheimer’s disease. That number is due to rise to one million by 2020 and two million by 2050.
Photo: Heathcliff O'Malley
The researchers say that targeting the initial cause of inflammation could prevent amyloid plaques ever forming.
“As of today, no therapeutic strategy has succeeded at changing the course of the disease,” said first author Dr Elena Rodriguez-Vieitez.
“The current therapies are only symptomatic, that is, they mitigate symptoms but they don’t change the course of the disease. So, an early diagnosis today would not help prevent dementia using with the currently available drugs.
“Our research aims at understanding especially the earliest phases of the disease. Clinical trials aimed at clearing amyloid plaques have not yet succeeded at curing the disease, and therefore it is necessary to find new therapeutic targets.”
The research was published in the journal Brain.
It comes as a second study appears to confirm the possibility that Alzheimer’s can be transmitted from person to person.
In September, a landmark study by scientists at University College London found Alzheimer's disease may be transmissible through blood transfusions and medical accidents in the same way as Creuzfeldt Jakob Disease (CJD).
Now a study – published in in the Swiss Medical Weekly – by researchers in Switzerland and Austria have reported autopsy results that suggest Alzheimer’s disease might occasionally be transmitted to people during certain medical treatments