New study finds link between intelligence at age 20 and future lung health

April 29, 2015

Can an intelligence test taken at age 20 predict poorer lung health later in life?

A new study from researchers at University of Florida Health, the University of Chicago, the University of California, San Diego and Boston University shows a link between poorer cognitive ability in young people and pulmonary problems later in life. The findings could help scientists create ways to minimize the effect.

“Aging and our health are very connected,” said Terrie Vasilopoulos, an assistant professor of anesthesiology in the UF College of Medicine and lead author on the study. “Things like cognition and other mental abilities are related to your physical health in some capacity and vice versa.”

The study, published in the March 2015 issue of the Journal of Epidemiology and Community Health, looked at data from the Vietnam Era Twin Study of Aging, a longitudinal study of cognition and aging beginning when participants were 51-60 years old. The participants represent a national sample of men who served in the U.S. military sometime between 1965 and 1975.

The data included information on the men’s pulmonary — or lung — function, such as how much air they could breathe in and out, and how easily they could do so.

The researchers then compared this data to the participants’ test scores from the Armed Forces Qualification Test, a general intelligence assessment that’s required of everyone entering the armed forces. At the time of the test, the study participants were, on average, 20 years old.

Even after adjusting for factors such as smoking, occupation, income and education, the researchers found that participants who did better on the intelligence test had better lung health 35 years later.

Specifically, individuals scoring in the top 25 percent on the Armed Forces Qualification Test had midlife forced expiratory lung volume that was 104 percent of the predicted normal function for those who are a similar age, ethnicity, body size and gender. Forced expiratory lung volume is the volume of air that can be exhaled during the first second of a forced breath, and predicted normal lung function is considered to be 100 percent, as compared to similar individuals.

Meanwhile, individuals scoring in the bottom 25 percent on the intelligence test had midlife forced expiratory lung volume at only 93 percent of the predicted normal function. In other words, individuals with the lowest intelligence scores in young adulthood had poorer than normal lung function for their age, ethnicity, body size and gender. Clinically, forced expiratory lung volume that is below 80 percent of the predicted normal values is considered a sign of lung disease, Vasilopoulos said. Furthermore, poorer lung function in midlife increases the risk of multiple diseases in older age, such as lung disease, cardiovascular disease and dementia, as well as earlier mortality.

“People with poor cognition earlier in life tend to have poorer health later in life,” she said. “One of the reasons they may be related is what they call health literacy; if you have poor cognition early in life, you may not be able to understand health messages that are communicated to you.”

While previous studies have found a relationship between cognitive function in childhood and lung function in adulthood, this is the first to show this relationship as it relates to specific measurements of lung function, such as lung volume and airflow. In doing so, the researchers found that one trait was unaffected by the correlation: lung obstruction, which is a marker of chronic obstructive pulmonary disease — the main cause of which is smoking.

Some studies suggest there’s also a genetic link between cognition and lung function. Next, Vasilopoulos hopes to study how different genes influence the relationship between pulmonary function and cognition.

“There’s still a lot to be done to understand the biological and social mechanisms underlying these relationships,” she said. “Perhaps not all the facets are related to cognition, because they have different genetic mechanisms.”

Understanding the role early cognitive ability plays in our future health is important, Vasilopoulos said.

“Your cognitive abilities really early in life are affecting health measures 30 to 40 years later,” she said. “We really need to understand this so we can intervene — so this relationship isn’t as strong.”

The study was funded by a National Research Service Award fellowship from the National Institutes of Health.