Heightened cognitive ability in adolescence linked to lower dementia risk decades later

An analysis of Project Talent Aging Study data has found that individuals who had better cognitive ability as adolescents were less likely to develop dementia 60 years later. Education played a mediating role, with better-educated individuals showing a reduced likelihood of developing dementia. The paper was published in the Journal of the Alzheimer’s Association.

Dementia is a general term for a decline in mental ability severe enough to interfere with daily life, encompassing various symptoms related to memory loss, reasoning, problem-solving, and other cognitive functions. It is typically caused by damage to or loss of nerve cells and their connections in the brain, which can affect behavior, feelings, and relationships. Dementia is most commonly seen in the elderly, although it is not a normal part of aging.

Research indicates an inverse relationship between cognitive abilities in childhood and the risk of developing dementia later in life. However, other studies suggest that the complexity of one’s education and occupation play minimal roles in predicting dementia risk.

Higher educational attainment and participation in mentally stimulating activities throughout life may slow cognitive decline or even reduce the risk of certain types of dementia. Scientists hypothesize that these activities help develop a ‘cognitive reserve’ that enables the brain to compensate for some dementia-related damage through alternative neural pathways or more efficient use of brain networks.

Much of the previous research has been retrospective, relying on data collected only when participants are already advanced in age. Study author Jimi Huh and his colleagues aimed to explore the impact of cognitive functioning in early life on cognitive status in later life, using data gathered when participants were young. They sought to identify early-life factors that influence general cognitive ability and whether additional education or occupations with higher cognitive demands could mitigate the risk of dementia.

The authors analyzed data from the Project Talent Aging Study (PTAS). As part of this project, high school students across the U.S. completed cognitive ability tests in 1960. A subset of these individuals was re-examined in 2018 (58 years later), where they underwent another evaluation of cognitive abilities and indicators of dementia, involving tasks that require cognitive skills and good working memory.

Originally, in 1960, 377,015 students participated in the PTAS. By 2018, researchers selected 22,584 individuals from this cohort for a new assessment, which included a self-report mail questionnaire, a phone-based battery of neurocognitive tests, and a web survey. Of these, 6,491 participants completed the mail questionnaire, which also featured a brief assessment for dementia. Ultimately, 2,411 completed the neurocognitive tests. The study’s findings were based on the responses of these participants, who had an average age of 74 years at the time.

For their analysis, the study authors used data on participants’ cognitive abilities made in 1960, attained education level, occupation complexity (evaluated using items from the Occupational Information Network database), dementia (assessed by the neurocognitive battery in 2018), and various sociodemographic data.

Results showed that participants with better cognitive abilities as adolescents, in 1960, tended to get better education later in life (i.e., have more years of formal education in total) and work on more complex jobs. Individuals with better cognitive abilities as adolescents (in 1960) were slightly less likely to have dementia symptoms in the 2018 assessment.

In a similar fashion, participants who attained more education and engaged in more complex jobs throughout their lives were somewhat less likely to exhibit dementia symptoms in 2018. The study authors tested a statistical model suggesting that cognitive abilities in adolescence not only directly affect dementia risk but also help individuals attain higher education and more complex jobs, which in turn may reduce the likelihood of developing dementia. The results confirmed that such relationships among these factors are indeed possible.

“We conclude that general cognitive ability measured relatively early in life strongly influences whether a person develops CI [cognitive impairment] or dementia much later in life and that those effects partially express themselves through their influence on how much education a person attains. Interventions focusing on continued learning, beyond compulsory education, as well as occupation-related activities during adulthood, may be incrementally beneficial in reducing CI or dementia,” the study authors concluded.

The study sheds light on the links between early cognitive ability and dementia later in life. However, it should be noted that participants whose data were analyzed in this study are just a small part of those whose data were collected back in 1960. This potentially leaves room for survival bias that could have affected the results.

The paper, “General cognitive ability in high school, attained education, occupational complexity, and dementia risk,” was authored by Jimi Huh, Thalida Em Arpawong, Tara L. Gruenewald, Gwenith G. Fisher, Carol A. Prescott, Jennifer J. Manly, Dominika Seblova, Ellen E. Walters, and Margaret Gatz.