We live longer and longer in good health, but our brains begin to show - discreet - signs of aging from the age of 45 years. This is the grim conclusion of a study published in the latest issue of British Medical Journal. Carried out by a research team from Inserm and University College London led by Archana Singh-Manoux, this work also shows that the decline is a little faster in men than in women (everyone will be able to draw their own conclusions, depending on their gender ...).
Everyone knows and can easily see on a daily basis that so-called cognitive performance gradually decreases with age. But until now it has been very difficult to define the point at which reasoning skills and speed of comprehension begin to falter. "Until now, it was generally accepted that there was no decline before 60 years", specify Inserm specialists in a press release explaining their work. They also recall that studies in patients show a correlation between the existence of so-called amyloid plaques in the brain and the severity of cognitive decline. These amyloid plaques, which are present in large numbers in people suffering from Alzheimer's disease, seem to exist in the brains of young adults.
Ten years of study
But this time, Archana Singh-Manoux's team wanted to assess the effect of age on cognitive decline, a field that has not yet been explored. It relied on the Whitehall II cohort, which collected medical data from 5 men and 198 women, aged 2 to 192 at the start of the study. All of these people were followed for ten years. Their cognitive functions have been assessed three times during this decade. Individual tests assessed the participants' memory, vocabulary, reasoning and verbal fluency.
The results show that cognitive performance (except for vocabulary tests) declines over time, and the faster the older people are. For example, over the study period, the decline in reasoning scores was 3,6% for men aged 45 to 49 and 9,6% for those aged 65 to 70. For women, the corresponding figures were 3,6% and 7,4% respectively. The authors do not provide any hypothesis to explain this difference.
"Determining the age at which cognitive decline begins is important because behavioral or pharmacological interventions designed to change the trajectories of cognitive aging are probably more effective if they are applied from the onset of the phenomenon", underlines Archana Singh-Manoux. “As life expectancy continues to increase, and this implies fundamental changes in the composition of populations, understanding age-related cognitive decline is one of the challenges of the XNUMXst century,” she concludes.