Mental decline sets in at 45 not 60, says study

Our brains start to deteriorate from as young as 45 — 15 years earlier than previously thought — according to a study published on Friday.

Memory, reasoning and comprehension skills, collectively known as cognitive function, all tend to get worse as we enter middle age, found the study of thousands of Whitehall civil servants.

While full-blown dementia is usually confined to old age, the study adds weight to a growing body of evidence suggesting the disease can take decades to develop.

Writing in the online edition of the British Medical Journal, the authors said that, before their study, there had been "little evidence of cognitive decline before the age of 60". However, they noted the premise that there was no actual mental decline pre-60 was "not universally accepted".

The researchers quantified the mental abilities of more than 7,000 civil servants between 1997 and 2007. Aged between 45 and 70 at the start, they were asked to undertake a series of tests at the beginning and end of the 10-year period.

For example, in one test they were asked to recall as many words beginning with "S" and as many animal names as possible from a list of words read to them. Other tests examined their vocabulary, aural and visual comprehension.

The researchers found those aged 45 to 49 in 1997 experienced a 3.6% decline in cognitive function over the decade.

Not surprisingly, the researchers found mental decline gathered pace with age: those in their late sixties in 1997 saw their abilities decline by 8.5% by 2007.

Although the research did not specifically look at participants' general health, the authors noted that other studies had indicated that those with better cardiovascular health in middle age tended to be less likely to develop dementia in old age.

The academics from the Centre for Research in Epidemiology and Population Health in France and University College London wrote: "There is emerging consensus that 'what is good for our hearts is also good for our heads'."

Commenting on the study, Francine Grodstein of the Brigham and Women's Hospital in Boston, Massachusetts, said: "This finding potentially has profound implications for prevention of dementia and public health. As yet, there is no cure for dementia, and accumulating evidence indicates that effective interventions will need to be administered long before marked neurodegeneration has occurred."

She added that efforts to prevent dementia "may need to start in adults as young as 45 years".

Dr Anne Corbett, of the Alzheimer's Society, welcomed the study, but added: "[It] does not tell us whether any of these people went on to develop dementia, nor how feasible it would be for GPs to detect these early changes."