As our population ages, brain health is becoming an increasing concern in patient care. Questions about brain health may concern cognitive performance, memory, verbal ability, or even general intelligence.
But what we call “intelligence” is actually a complex system of brain structures, cognitive functions, and expressions of skill. Research shows that multiple neural systems actually contribute together to what we traditionally think of as expressions of intelligence.
While neural systems are partially shaped by genetic factors, there’s still plenty that patients can do to keep cognitive abilities at their best. Other factors that go into the development of intelligence can include physical fitness, learning new skills, healthy habits, and social connectedness.
When it comes to communicating the complex traits and nature of intelligence to your patients, it may help to be clear about what’s within their control—and what might be in their makeup. Read on for more about the role genetics play in the development of intelligence, and how best to support your patients who want to maintain good cognitive function.
How Much of Intelligence is Genetic?
In a 1994 issue of the Wall Street Journal, Linda S. Gottfredson summarized views of intelligence researchers that have since proved to be highly controversial and inaccurate. However, the statement also provided a useful definition of general intelligence: "a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience."
Many of these skills are acquired through the course of a person’s life. But it’s also true that they come more easily to some people than others.
The reasons for that could be partially explained by genetic predisposition. Genome-wide association studies (GWAS) have been conducted on a wide scale in recent decades trying to get to the bottom of how heritable intelligence is, and which genes are involved.
“The genetic contribution to intelligence differences is highly polygenic,” wrote Ian J. Deary, Simon R. Cox, and W. David Hill in an aggregate study of genetically-linked intelligence data in 2022. In other words, “there are large numbers of independent genetic variants, each of which accounts for a tiny proportion of intelligence variation.”
The overall degree to which genes account for intelligence is usually estimated to be at least half, or as high as 80%, with the rest accounted for by environment and life experience. However, a strong genetic influence on intelligence does not mean that environment is not important, or that intelligence cannot be changed. As Bruno Sauce and Louis D. Matzel (2018) summarize, there is plenty of evidence that intelligence is both heritable and malleable.
The interplay between genetic and environmental influences is not yet fully understood yet, but acknowledging the importance of both is key to removing barriers to improved brain health, particularly in under-privileged patient populations.
So is there such thing as an “IQ gene”?
While there may well be biological reasons for why one patient’s brain works a certain way, there’s no such thing as a single “IQ gene”—instead, it is likely hundreds of genes working together and interacting with environmental factors to determine cognitive abilities. How much genetic influence plays a part in learning or planning may even vary from person to person.
This said, research is ongoing and growing rapidly in this field. Practitioners may benefit from keeping up to date on the ongoing debates and emerging information when it comes to figuring out how to talk to their patients about brain health.
How Is Intelligence Measured?
We’re all familiar with the concept of IQ tests, which test cognitive abilities such as spatial reasoning, memory, verbal ability, and reaction time.
A full neuropsychological examination that includes intelligence testing can take 4 hours more. Then, after all that, the focus is often on an aggregate IQ number. What happened to the details?
Quicker computerized cognitive tests might be more appropriate in many healthcare contexts, and can measure domains like reasoning, short-term memory, and verbal ability. Getting higher scores in some domains or subdomains than others is normal, and provides more detail than an aggregate number representing an individual’s overall intelligence.
Knowing where an individual’s cognitive strengths and weaknesses are might give practitioners more information on how best to advise their patients. Cognitive tests like these, as well as assessments tailored more narrowly to measure specific areas of cognitive function, can also help to catch early signs of cognitive dysfunction in older demographics.
Can a Person Increase Their Intelligence?
The brain is an active, elastic, ever-changing organ. It’s never stagnant—and neither are intelligence skills!
We’ve covered how a number of biological factors, from brain structure to genetics, can affect how a person thinks. The good news is that social and environmental factors, as well as lifestyle factors, can also play a significant role.
People’s always-changing environments and ability to alter their habits means that no one’s intelligence is a fixed trait. Here are just a few ways patients worried about their cognitive abilities can make a difference in their thinking skills.
Read more: Does Brain Training Work?
Engage in Appropriate Exercise
Physical activity can enhance brain function in people of any age. It’s well known that exercise is shown to help with mental health, but it can also help improve performance in nearly every domain of cognition, suggesting that level of physical activity is one non-genetic factor that determines an individual's overall intelligence.
Some studies even show that older adults who exercise regularly are up to 17% less likely to report subjective cognitive decline. Exercise may make the difference in staying sharper for longer.
Intense, aerobic exercise may not be the right fit for every patient. When advising patients, noting that any amount of exercise—whatever is within their ability—may produce health benefits may help them feel empowered to make a beneficial lifestyle change.
Read more: Is Exercise Good for the Brain? Here's What the Science Says.
Learn a New Skill
Every time we learn something new, our brain lights up in a flurry of activity, which may lead to better brain health.
According to Dr. John N. Morris at the Institute of Aging Research, the three skill-building factors that make the biggest difference in cognitive ability are:
- Challenge.Even challenging a patient to reach a new bar in an activity they already enjoy has benefits!
- Complexity. Problem-solving is an important skill in robust cognitive function.
- Ease of practice.Among other things, practicing a skill is a great way to exercise memory. According to Dr. Morris, returning to a skill again and again may be even more important than mastering it.
What about easier activities, like online brain training? We’ve found that simple games have no association with overall cognitive performance. There’s still no quick fix for the brain; improving intelligence requires dedication to complex skills.
Build New—or Stronger—Habits
It’s no secret that cutting down on tobacco and alcohol can help improve health outcomes. But building new habits can be just as beneficial.
Regularly reading a book can create all kinds of positive reactions in the brain. Adults who regularly do puzzles also reflect higher levels of cognitive functions.
Get Quality Sleep
Sleep might be the most important habit of all to build. With strong connections to cognitive and mental health, getting the right amount of sleep is a significant determinant of health. The amount of sleep everyone needs is different, but some studies suggest 7 hours per night is the needed baseline for robust cognitive function.
Talk to Family and Friends
A study of Japanese adults showed that regular social exposure was linked to healthy brain structure and volume. Strengthening thinking skills can be as easy as hanging out, catching up, or even striking up a conversation while walking the dog.
Living with someone, small talk with new people, or weekly classes are all great ways to keep brains healthy and active. Patients could even mix social time with another activity and gain multiple benefits at once. A regular walking date with a neighbor offers a great double-whammy of chatting while exercising.
Read more: How To Prevent Dementia: 12 Modifiable Risk Factors
Final Thoughts: DNA Is Not Destiny
Though our genes and physical bodies have a lot of say on how we move through the world, there’s still plenty patients can do to help improve their thinking skills. Framing intelligence as merely shorthand for a whole network of pathways, structures, chemicals, and skills may help patients feel more at ease with variations in their cognitive performance.
To help guide patients concerned about their brain health, focus on the factors they can control, like skills-building, appropriate exercise, and other relevant lifestyle factors. Another approach may be to look into cognitive tests that measure performance in a number of different areas, instead of reducing intelligence to a single number.
Not only does more comprehensive cognitive information put patients at ease, but it improves your ability to provide quality patient care by pinpointing where actual deficits may exist—and where they don’t.