Researcher Looks at Link Between Intelligence, Health, and Aging
Curators’ Distinguished Professor of Psychological Sciences David Geary’s research focuses on sex differences and sex-specific vulnerabilities. For example, prenatal exposure to toxins and other stressors can affect girls differently than boys, or vice versa. He says his research led him to develop a model about general biological differences and sensitivity to environmental and social stressors that focused on mitochondria—little organelles inside cells that produce adenosine triphosphate (ATP) or cellular energy.
“Mitochondria are responsible for cellular energy production but they also are involved in some stages of hormone synthesis, immunity, and a lot of other things,” Geary says. “They are amazingly versatile and are critically important but are generally overlooked.”
Geary also had written a book on brain evolution, cognition, and intelligence, and he had been reviewing research showing correlations between how well a person does on cognitive measurements and measurements of general health and successful aging. Then he had a flash of insight.
“It just occurred to me that mitochondrial functioning could explain all of these relationships and more because it is so central to so many basic cognitive and health processes and the rate of aging,” he says.
Geary developed a model showing basic mitochondrial functioning is important for brain development and cognitive development. He says if a person is good at reading, they tend to be good at math, and that is often called general intelligence—a concept that has intrigued scientists for more than 100 years. He says mitochondrial functioning could be one of the core features of general intelligence, and if it is the core, it may be the basic fundamental mechanism linking cognitive outcomes with health and aging outcomes.
Sensitive Little Engines
Geary says a number of factors can influence mitochondrial functioning. For example, the generation of cellular energy creates oxidative stress—an imbalance between free radicals and antioxidants in your body, which can invade mitochondrial DNA and create mutations. Add to that the fact that large, complex organs such as the brain or the heart use a lot of energy, putting heavy demands on the mitochondria.
“So you use these systems over and over again, but their heavy use eventually results in their gradual decline, which some have argued is the basis for aging,” he says. “That would explain parallel changes in cognition and health associated with aging.”
Geary says mitochondria also are sensitive to stress and environmental factors, such as cigarette smoke, which can undermine the efficiency with which they produce energy.
“If you have a systemic stressor that goes throughout the body, then it’s going to affect everything—the brain is not going to work as efficiently, the heart is not going to work as well, your speed of reacting to things is going to slow down,” he says. “All of these things occur simultaneously and that’s why you see those relations.”
Doctor Knows Best
It turns out we have had the key to maintaining good health and aging gracefully for some time, but some of us are better at acting upon the information than others.
“Just the things your doctor would tell you—exercise regularly and eat a regular diet with anti-oxidants like fruits and vegetables,” he says. “These will boost the protective mechanisms the mitochondria have, and if you exercise, that will produce more mitochondria, and it will increase blood flow. There’s a reason why things like exercise improve cognition as well as physical health.”
Geary says his approach may be useful for identifying genetic and environmental influences on the development of intelligence and the rate of age-related declines in cognition. He says his proposal means that emerging mitochondrial therapies for specific diseases such as Alzheimer’s could have much wider uses.