A new European study has strong implications for future health policy as researchers found cognitive decline may begin in the mid-40s rather than after the age of 60.
Experts say knowing when cognitive decline begins is important as pharmacological and behavioral intervention is more effective when initiated early in the course of care.
Moreover, in the context of increased life expectancies and aging populations around the world, there may well be a significant rise in the number of elderly people with various degrees of cognitive decline.
Abundant evidence has clearly established an inverse association between age and cognitive performance, but the age at which cognitive decline begins has been debated.
Recent clinical studies have demonstrated a correlation between the presence of amyloid plaques in the brain and the severity of cognitive decline. Further, new research methods and technology have helped detect amyloid plaques in the brains of young adults.
In the current study, researchers assessed the effect of age on cognitive decline over a multi-year period. This longitudinal study design is unique and a method researchers believe improves validity and generalizability of the findings.
Over a 10-year period, medical data from the Whitehall II cohort study was analyzed. The study is an ongoing assessment of 5,198 men and 2,192 women, aged between 45 and 70.
The cognitive function of the participants was evaluated three times over this time. Individual tests were used to assess memory, vocabulary, reasoning and verbal fluency.
The results show that cognitive performance (apart from the vocabulary tests) declines with age and more rapidly so as the individual’s age increases. The decline is significant in each age group.
For example, during the period studied, reasoning scores decreased by 3.6 percent for men aged between 45 and 49, and 9.6 percent for those aged between 65 and 70. The corresponding figures for women stood at 3.6 percent and 7.4 percent respectively.
The authors believe the discovery that cognition declines before the age of 60 has significant consequences.
“Determining the age at which cognitive decline begins is important since behavioral or pharmacological interventions designed to change cognitive aging trajectories are likely to be more effective if they are applied from the onset of decline,” said Archana Singh-Manoux, Ph.D., of the Centre for Research in Epidemiology and Population Health.
“As life expectancy continues to increase, understanding the correlation between cognitive decline and age is one of the challenges of the 21st Century” she said.
The study is published in the British Medical Journal.
Source: INSERM (Institut national de la santé et de la recherche médicale)