Signs of dementia may be detectable nine years before diagnosis - study

Scientists have discovered that it may be possible to spot signs of dementia as early as nine years before patients receive an official diagnosis.

The findings raise the possibility that, in the future, at-risk people could be screened to help select those who could benefit from interventions, or help identify patients suitable for clinical trials for new treatments.

Researchers at Cambridge University published the study - funded by the Medical Research Council with support from the NIHR Cambridge Biomedical Research Centre - in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.

Dr Richard Oakley, associate director of research at the Alzheimer's Society, said the "important" findings suggested that "for some people who go on to develop Alzheimer's disease, memory and thinking problems can begin up to nine years before they receive a diagnosis".

He added: "This opens up the possibility of screening programmes in the future to help identify people at risk and who may benefit from interventions, and identify more people suitable for clinical trials for new dementia treatments, which are both so desperately needed."

The study's first author, Nol Swaddiwudhipong, said: "When we looked back at patients' histories, it became clear that they were showing some cognitive impairment several years before their symptoms became obvious enough to prompt a diagnosis. The impairments were often subtle, but across a number of aspects of cognition.

"This is a step towards us being able to screen people who are at greatest risk - for example, people over 50 or those who have high blood pressure or do not do enough exercise - and intervene at an earlier stage to help them reduce their risk."

In the study, researchers analysed data from the UK Biobank and found impairment in several areas, such as problem solving and number recall, across a range of conditions, years before patients received an official diagnosis.

There are currently very few effective treatments for dementia. Experts say this is partly because the condition is often diagnosed only once symptoms appear, whereas the underlying issue may have begun years or even decades earlier.

That means that by the time patients take part in clinical trials, it can already be too late in the disease to alter its course.

Until now, it has been unclear whether it could be possible to detect changes in brain function before the onset of symptoms.

As well as collecting information on health and disease diagnoses, researchers collected data from a range of tests, including problem solving, memory, reaction times and grip strength, as well as data on weight loss and gain and on the number of falls experienced.

This allowed researchers to see whether any signs were present at baseline, when measurements were first collected between five and nine years before diagnosis.

People who went on to develop Alzheimer's scored more poorly compared with healthy individuals when it came to problem solving tasks, reaction times, remembering lists of numbers, and memory. According to the study, they were also more likely than healthy adults to have had a fall in the previous 12 months.

The senior author, Dr Timothy Rittman, from Cambridge's Department of Clinical Neurosciences, said: "People should not be unduly worried if, for example, they are not good at recalling numbers. Even some healthy individuals will naturally score better or worse than their peers. But we would encourage anyone who has any concerns or notice that their memory or recall is getting worse to speak to their GP."