Dementia 'can start as early as age 45, not 60'

Study contradicts past notions and poses big challenge in search for ways to prevent ailment
The Straits Times, 7 Jan 2012

LONDON: Loss of memory and other brain function can start as early as age 45, posing a big challenge to scientists looking for new ways to stave off dementia, researchers said on Thursday.

The finding from a 10-year study of more than 7,000 British government workers contradicts previous notions that cognitive decline does not begin before age 60, and it could have far-reaching implications for dementia research.

Pinpointing the age at which memory, reasoning and comprehension skills start to deteriorate is vital as drugs are most likely to work if given when people first start to experience mental impairment.

A handful of novel medicine for Alzheimer's disease, the most common form of dementia, is now in clinical trials, but expectations are low and some experts fear the new drugs are being tested in patients who may be too old to show a benefit.

The research team, led by Dr Archana Singh-Manoux from the Centre for Research in Epidemiology and Population Health in France and University College London, found a modest decline in mental reasoning in men and women aged 45 to 49.

'We were expecting to see no decline, based on past research,' said Dr Singh-Manoux in a telephone interview.

Many societies face an 'exponential increase' in the number of elderly people as a result of increases in life expectancy, the research paper noted.

'These changes are likely to have a profound influence on individuals' lives and society at large. Poor cognitive status is perhaps the single most disabling condition in old age.'

Among older subjects in the study, the average decline in cognitive function was greater, but there was a wide variation at all ages, with a third of individuals aged 45 to 70 showing no deterioration over the period.

'It doesn't suddenly happen when you get old. That variability exists much earlier on,' Dr Singh-Manoux said. 'The next step is going to be to tease that apart and look for links to risk factors.'

Participants were assessed three times during the study, using tests for memory, vocabulary, and aural and visual comprehension skills.

Over the 10-year period, there was a 3.6 per cent decline in mental reasoning in both men and women aged 45 to 49 at the start of the study, while the decline for men aged 65 to 70 was 9.6 per cent and for women, 7.4 per cent.

Since the youngest individuals at the start of the study were aged 45, it is possible that the decline in cognition might have commenced even earlier.

Dr Singh-Manoux said the results may also have underestimated the cognitive decline in the broader population, since the office workers in the study enjoyed a relatively privileged and healthy lifestyle.

Factors affecting cardiovascular function - such as obesity, high blood pressure, high cholesterol and smoking - are believed to have an impact on the development of Alzheimer's and vascular dementia through effects on brain blood vessels and brain cells.

The research findings were published in the British Medical Journal, alongside an editorial by Dr Francine Grodstein of the Brigham and Women's Hospital in Boston, who described the results as convincing.

Most research into dementia has focused on people aged 65 and over. In future, scientists will need to devise long-term clinical studies that include much younger age groups and may have to enrol tens of thousands of participants, she said.

REUTERS, AGENCE FRANCE-PRESSE