Experts from the University of Exeter and University College London (UCL) have developed a cognitive test to detect subtle memory deficits years before Alzheimer's disease symptoms develop, set out in a new paper published in The Lancet Neurology.
The study involved 21 people who carry the mutation for early onset Alzheimer's disease who have not shown any symptoms based on standard cognitive tests, alongside 14 controls. On average the study participants were seven years away from predicted onset of symptomatic disease.
The participants underwent a memory test with 30-minute recall, and were then checked seven days later to see if they still remembered. The authors found that people who were closest to the expected onset of symptoms could remember things after 30 minutes but then had forgotten things after seven days.
The researchers say their findings demonstrate that memory formation wasn't the issue, so typical tests wouldn’t identify any problems.
Professor Adam Zeman, one of the co-authors of the paper from the University of Exeter Medical School, said: “This exciting work may lead to new approaches to early diagnosis and monitoring of Alzheimer's disease and its treatments.”
Professor Nick Fox, senior author of the paper from UCL, said: “It is clear that in Alzheimer’s disease there are changes in the brain that occur long before people have obvious symptoms – and this may be when treatments have their best chance of being effective. We found that people without symptoms but who carry a genetic mutation causing Alzheimer’s disease have difficulty retaining memories over longer periods than are used in conventional test – essentially, accelerated forgetting.”
The researchers found a correlation between long-term forgetting and subjective memory complaints. They say this could be the earliest test to detect changes in someone’s cognition that lead to Alzheimer’s disease.
They say their study advances the scientific understanding of how exactly memory losses begin, as the researchers say this kind of long-term forgetting seems to start quite early.
While the study was only done in people who carry the mutation for autosomal dominant Alzheimer’s disease, alongside healthy controls, the researchers are hopeful that their findings would also be relevant to later-onset (sporadic) Alzheimer’s disease, as the disease progression is understood to be very similar. The early test could help identify people for early clinical trials, in addition to helping monitor whether a treatment is working.
The study involved researchers at UCL, the London School of Hygiene & Tropical Medicine, the University of Oxford and the University of Exeter, and was funded by the Medical Research Council, the National Institute for Health Research, Alzheimer's Research UK, Dementias Platform UK, Dunhill Medical Trust, Epilepsy Research UK, Great Western Research, Health Foundation and the Patrick Berthoud Trust.