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
Arts and Entertainment
Written protest: Julia Donaldson, author of The Gruffalo, has sent an open letter to the Culture Secretary
books
Arts and Entertainment
The teaser trailer has provoked more questions than answers
filmBut what is Bond's 'secret' that Moneypenny is talking about?
Sport
Lewis Hamilton secured his second straight pole of the season
f1Vettel beats Rosberg into third after thunderstorm delays qualifying
ebooks
ebooksA special investigation by Andy McSmith
News
Johnny Depp is perhaps best known for his role as Jack Sparrow in Pirates of the Caribbean
peopleBut how did he break it?
Sport
footballDoes Hodgson's England team have an identity yet?
Travel
travel Dreamland Margate, Britain’s oldest amusement park, is set to reopen
News
news
News
Founders James Brown and Tim Southwell with a mock-up of the first ever ‘Loaded’ magazine in 1994
media
  • Get to the point
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

Ashdown Group: Practice Accountant - Bournemouth - £38,000

£32000 - £38000 per annum: Ashdown Group: A successful accountancy practice in...

SThree: Trainee Recruitment Consultant

£18000 - £23000 per annum + Uncapped commission: SThree: Does earning a 6 figu...

Recruitment Genius: SEO Executive

£18000 - £25000 per annum: Recruitment Genius: This is an exciting opportunity...

Recruitment Genius: New Lift Sales Executive - Lift and Elevators

£35000 - £40000 per annum: Recruitment Genius: A challenging opportunity for a...

Day In a Page

The saffron censorship that governs India: Why national pride and religious sentiment trump freedom of expression

The saffron censorship that governs India

Zareer Masani reveals why national pride and religious sentiment trump freedom of expression
Prince Charles' 'black spider' letters to be published 'within weeks'

Prince Charles' 'black spider' letters to be published 'within weeks'

Supreme Court rules Dominic Grieve's ministerial veto was invalid
Distressed Zayn Malik fans are cutting themselves - how did fandom get so dark?

How did fandom get so dark?

Grief over Zayn Malik's exit from One Direction seemed amusing until stories of mass 'cutting' emerged. Experts tell Gillian Orr the distress is real, and the girls need support
The galaxy collisions that shed light on unseen parallel Universe

The cosmic collisions that have shed light on unseen parallel Universe

Dark matter study gives scientists insight into mystery of space
The Swedes are adding a gender-neutral pronoun to their dictionary

Swedes introduce gender-neutral pronoun

Why, asks Simon Usborne, must English still struggle awkwardly with the likes of 's/he' and 'they'?
Disney's mega money-making formula: 'Human' remakes of cartoon classics are part of a lucrative, long-term creative plan

Disney's mega money-making formula

'Human' remakes of cartoon classics are part of a lucrative, long-term creative plan
Lobster has gone mainstream with supermarket bargains for £10 or less - but is it any good?

Lobster has gone mainstream

Anthea Gerrie, raised on meaty specimens from the waters around Maine, reveals how to cook up an affordable feast
Easter 2015: 14 best decorations

14 best Easter decorations

Get into the Easter spirit with our pick of accessories, ornaments and tableware
Paul Scholes column: Gareth Bale would be a perfect fit at Manchester United and could turn them into serious title contenders next season

Paul Scholes column

Gareth Bale would be a perfect fit at Manchester United and could turn them into serious title contenders next season
Inside the Kansas greenhouses where Monsanto is 'playing God' with the future of the planet

The future of GM

The greenhouses where Monsanto 'plays God' with the future of the planet
Britain's mild winters could be numbered: why global warming is leaving UK chillier

Britain's mild winters could be numbered

Gulf Stream is slowing down faster than ever, scientists say
Government gives £250,000 to Independent appeal

Government gives £250,000 to Independent appeal

Donation brings total raised by Homeless Veterans campaign to at least £1.25m
Oh dear, the most borrowed book at Bank of England library doesn't inspire confidence

The most borrowed book at Bank of England library? Oh dear

The book's fifth edition is used for Edexcel exams
Cowslips vs honeysuckle: The hunt for the UK’s favourite wildflower

Cowslips vs honeysuckle

It's the hunt for UK’s favourite wildflower
Child abuse scandal: Did a botched blackmail attempt by South African intelligence help Cyril Smith escape justice?

Did a botched blackmail attempt help Cyril Smith escape justice?

A fresh twist reveals the Liberal MP was targeted by the notorious South African intelligence agency Boss