Researchers in France and the UK looked at 5,198 men and 2,192 women aged between 45 and 70 over a 10-year period from 1997. Participants' cognitive functions including memory, vocabulary and aural and visual comprehension skills were assessed three times.
The study found there was a 3.6 per cent decline in mental reasoning in women and men aged 45-49.
Alzheimer's Society comment:
'This large, important study adds vital information to the debate over when cognitive decline begins. However, the study 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.
'More research is now needed to help us fully understand how measurable changes in the brain can help us improve diagnosis of dementia. An early diagnosis is essential as it can provide access to support and potential treatments which can vastly improve people's quality of life.'
Dr Anne Corbett