Youthful general cognitive ability (GCA), a multiple set of skills involved in perception, memory, and thinking which includes reasoning, is a ‘strong predictor of cognitive function’ and reserve later in life compared to other factors including higher education, complex occupations, and participating in late-life intellectual activities, according to a recent study.
Higher education and late-life intellectual pursuit like socializing, reading, or solving puzzles are linked with improved cognitive reserve and lower risk of dementia. Cognitive reserve is the ability of the brain to improvise or find alternate ways to complete a task, and may even help people adjust with changes related to aging.
In the new study, a team of researchers at the University of California San Diego sought to address the confusion posed by these associations; whether being in highly complex occupation help maintain cognitive abilities or individuals with higher cognitive ability are likely to be in more complex jobs.
The team examined over 1,000 men taking part in the Vietnam Era Twin Study of aging. All were veterans, of which around 80% have reported no combat experience. In addition, all the participants, now aged between 50 and 60 years, took the Armed Forces Qualification Test in their 20s which is a measure GCA.
As part of the new study, the research team assessed performance of participants who are in their mid-60s using the same GCA measure, including assessments in seven different cognitive domains such as verbal fluency, abstract reasoning, and memory.
The researchers found that participants’ GCA at age 20 accounted for 40% of the variance in the same measure at age 62, and nearly 10% of the variance in each cognitive domain. After the GCA analysis, they concluded that other factors had no or very small effect; lifetime education, job complexity, and participating in intellectual activities accounted for even less than 1% of variance at age 62.
Findings of the study, published in the journal PNAS, suggest that the impact of other factors than GCA on cognitive function later in life likely reflects reverse causations. According to first author William S. Kremen, they are widely downstream effects of youthful intellectual capacity.
Further, the researchers discovered that age 20 GCA, but not higher education, was associated with the surface area of the cerebral cortex at the age 62. This part of the brain is responsible for thinking, understanding language, perceiving, and producing.
Additional investigations are needed to confirm the finding, the researchers said.