Lower cognitive ability in young adulthood was found to predict a higher risk of early-onset dementia among men from the Helsinki Birth Cohort Study in a study by Rantalainen and others, recently published in Neurology.
Men with lower cognitive ability scores at 20 years of age had a higher risk of receiving a diagnosis of dementia before 65 years of age, but not at later ages.
The associations were strongest with the total cognitive ability and verbal reasoning ability scores and were not explained by childhood socioeconomic status or maternal or early developmental factors. While lower arithmetic and visuospatial reasoning ability were also associated with a higher risk of early-onset dementia, these associations were weaker. However, the associations were not independent from the participant’s education, likely because cognitive ability and educational attainment are quite closely related.
Higher cognitive ability is thought to protect against dementia due to a more robust brain structure and learned cognitive skills and strategies that help preserve a higher-ability individual’s ability to function. The finding that cognitive ability predicted early-onset, but not late-onset dementia risk is likely related to heritable and non-heritable factors influencing cognitive ability to a different degree at different points in the lifespan, as individuals choose occupational, social and other environments according to their genetic predispositions.
/ Ville Rantalainen