Alzheimer's can be spotted decades before illness starts

People at high risk of developing Alzheimer's disease in later life possess hidden signs of the senile disorder decades before the onset of the illness, scientists have found.

The findings might eventually form the basis of a diagnostic test for Alzheimer's which could enable doctors to identify and treat people who would otherwise be destined to develop the progressive illness.

Abnormalities in the brain of people aged between 20 and 40, who carried a gene that is known to increase the risk of Alzheimer's, were discovered in a study by Eric Reiman and colleagues at the University of Arizona in Tucson.

The abnormalities do not appear to affect people's mental abilities but they do seem to indicate that something is beginning to happen long before the onset of the traditional symptoms of the disease, such as forgetfulness and mental distraction. The same "functional" abnormalities - low rates of glucose metabolism in specific regions of the brain - are also found in older patients with the disease, the scientists report in the journal Proceedings of the National Academy of Sciences.

Alzheimer's disease affects some 10 per cent of people over the age of 65, and almost half of those aged 85 or over.

With more people living longer, the proportion of the population affected by the disease will rise significantly in the next 20 years. A method of diagnosing Alzheimer's early in a patient's life could help doctors to develop better preventative treatments or even drugs that could delay the onset of symptoms.

Different varieties of a gene known as APOE - which is responsible for a protein called apolipoprotein E - are linked with different risks of developing Alzheimer's, with one version, known as APOE-4, resulting in the highest risk.

When people inherit two copies of the APOE-4 gene, one from their father and one from their mother, the chances of developing Alzheimer's by the time they are aged 70 rises to more than 90 per cent.

Dr Reiman wanted to assess the brains of younger people aged between 20 and 40 in order to compare those carrying both maternal and paternal copies of the APOE-4 version of the gene with those who had other versions of the gene. Using a sophisticated brain scanner that could measure the rate at which the brain uses up its supply of glucose - the "fuel" that keeps brain cells alive and active - the scientists found a way of comparing the mental activity of the two groups of volunteers in the experiment.

Dr Reiman's team found that the carriers of APOE-4 had abnormally low levels of activity in precisely the same areas of the brain seen to be low in activity in Alzheimer's patients.

"Carriers of a common Alzheimer's susceptibility gene have functional brain abnormalities in young adulthood, several decades before the possible onset of dementia," the researchers say.

"Our findings raise the possibility that functional alterations provide a foothold for the subsequent onset of neuropathology [disease] in brain regions that are preferentially vulnerable to this disorder," they say.

If this is true - and the scientists want further research to be done - then it raises the possibility that drugs or therapy may be developed to counteract the abnormalities in the way the brain functions before they develop into the full-blown disease.

A number of studies have suggested that people with active mental lives - those for instance who do crosswords or memory tests - are less prone to developing Alzheimer's. Some scientists have called this the "use it, or lose it" phenomenon.

Start your day with The Independent, sign up for daily news emails
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Parts Advisor

£16500 - £18500 per annum: Recruitment Genius: One of the leading Mercedes-Ben...

Recruitment Genius: Software Developer

£27500 - £35000 per annum: Recruitment Genius: This is an exciting opportunity...

Recruitment Genius: Telemarketers / Sales - Home Based - OTE £23,500

£19500 - £23500 per annum: Recruitment Genius: Experienced B2B Telemarketer wa...

Recruitment Genius: Showroom Assistant

Negotiable: Recruitment Genius: This global company are looking for two Showro...

Day In a Page

Fifa corruption: The 161-page dossier that exposes the organisation's dark heart

The 161-page dossier that exposes Fifa's dark heart

How did a group of corrupt officials turn football’s governing body into what was, in essence, a criminal enterprise? Chris Green and David Connett reveal all
Mediterranean migrant crisis: 'If Europe thinks bombing boats will stop smuggling, it will not. We will defend ourselves,' says Tripoli PM

Exclusive interview with Tripoli PM Khalifa al-Ghweil

'If Europe thinks bombing boats will stop smuggling, it will not. We will defend ourselves'
Raymond Chandler's Los Angeles: How the author foretold the Californian water crisis

Raymond Chandler's Los Angeles

How the author foretold the Californian water crisis
Chinese artist who posted funny image of President Xi Jinping facing five years in prison as authorities crackdown on dissent in the arts

Art attack

Chinese artist who posted funny image of President Xi Jinping facing five years in prison
Marc Jacobs is putting Cher in the limelight as the face of his latest campaign

Cher is the new face of Marc Jacobs

Alexander Fury explains why designers are turning to august stars to front their lines
Parents of six-year-old who beat leukaemia plan to climb Ben Nevis for cancer charity

'I'm climbing Ben Nevis for my daughter'

Karen Attwood's young daughter Yasmin beat cancer. Now her family is about to take on a new challenge - scaling Ben Nevis to help other children
10 best wedding gift ideas

It's that time of year again... 10 best wedding gift ideas

Forget that fancy toaster, we've gone off-list to find memorable gifts that will last a lifetime
Paul Scholes column: With the Premier League over for another year, here are my end of season awards

Paul Scholes column

With the Premier League over for another year, here are my end of season awards
Heysel disaster 30th anniversary: Liverpool have seen too much tragedy to forget fateful day in Belgium

Liverpool have seen too much tragedy to forget Heysel

Thirty years ago, 39 fans waiting to watch a European Cup final died as a result of a fatal cocktail of circumstances. Ian Herbert looks at how a club dealt with this tragedy
Amir Khan vs Chris Algieri: Khan’s audition for Floyd Mayweather may turn into a no-win situation, says Frank Warren

Khan’s audition for Mayweather may turn into a no-win situation

The Bolton fighter could be damned if he dazzles and damned if he doesn’t against Algieri, the man last seen being decked six times by Pacquiao, says Frank Warren
Blundering Tony Blair quits as Middle East peace envoy – only Israel will miss him

Blundering Blair quits as Middle East peace envoy – only Israel will miss him

For Arabs – and for Britons who lost their loved ones in his shambolic war in Iraq – his appointment was an insult, says Robert Fisk
Fifa corruption arrests: All hail the Feds for riding to football's rescue

Fifa corruption arrests

All hail the Feds for riding to football's rescue, says Ian Herbert
Isis in Syria: The Kurdish enclave still resisting the tyranny of President Assad and militant fighters

The Kurdish enclave still resisting the tyranny of Assad and Isis

In Syrian Kurdish cantons along the Turkish border, the progressive aims of the 2011 uprising are being enacted despite the war. Patrick Cockburn returns to Amuda
How I survived Cambodia's Killing Fields: Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape the US

How I survived Cambodia's Killing Fields

Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape to the US
Stephen Mangan interview: From posh buffoon to pregnant dad, the actor has quite a range

How Stephen Mangan got his range

Posh buffoon, hapless writer, pregnant dad - Mangan is certainly a versatile actor