A new study finds that education, income, and the type of job may all make it more likely that people in their mid-50s are still mentally sharp.

An analysis of data from more than 7,000 adults in the U.S. showed that these factors could explain nearly 40% of the differences in how much cognitive ability people had lost by age 54. Scientists from Ohio State University wrote in a scientific journal on Wednesday that a person’s education, and especially whether or not they went to college, made the biggest difference in their memory, judgement, and ability to focus.

The researchers looked at information from the Health and Retirement Study at the University of Michigan, which has been following more than 20,000 participants for more than 20 years. The study’s database has information about each participant’s income, job, and education, as well as personal details like their history of marriage, religion, depression, and cognitive abilities, as well as their body mass index, level of activity, smoking history, and other details about their physical health.

Researchers looked at data from a single group of 7,068 adults who were 54 to 65 years old in 1996 and then again 20 years later.

Hui Zheng, a professor of sociology and one of the authors of the study, thinks that the reason people with a college degree are smarter in their 50s is because they are more likely to have a job that requires them to use their brains.

He said, “If you have a job that makes you think, you’re lucky, because you’re always using your brain.” “The better your job is, the more challenging it is for your mind.”

Still, going to college in our 20s is not the only way to keep our minds from getting worse before our mid-50s. Research from the past has shown that having hobbies and interests that keep the brain active, like learning a new language, painting, or writing, can also be helpful.

Even though the study looked at a wide range of factors that affect brain health as we age, it didn’t look at genetics, which experts say could play a big role in cognitive function.

Dr. Thomas Wisniewski, a neuropathologist and the director of the NYU Langone Alzheimer’s Disease Research Center and its Center for Cognitive Neurology, said that previous research has shown that education, household wealth, and access to health care are linked to the brain’s resilience.

Still, he said, the fact that factors that people can mostly control might explain as much as 40% of the differences in the loss of cognitive abilities at age 54 is “good news.” This is because genetics only account for about 10% of the differences.

The Ohio study found that things like keeping a healthy weight, not smoking, and doing a lot of vigorous exercise didn’t have much of an effect on the rate of cognitive decline after age 54. However, Wisniewski, who was not involved in the study, isn’t convinced that “there’s nothing you can do about it.”

“As a doctor, I know that’s not true, and other studies have shown the same thing,” he said.
When it comes to slowing cognitive decline, physical activity and a healthy diet can be highly beneficial, Wisniewski said. Taking care of health problems like obstructive sleep apnea, diabetes, high blood pressure, and high cholesterol is also helpful.

To show how important vigorous physical activity is even for people in their 70s, he points to one of his recent papers, which was about two patients with mild cognitive impairment and biological signs that they would get Alzheimer’s disease.

Once the patients either retired or cut the time spent on the job, they had more time for vigorous exercise. And they both spent more time working out. There were no signs of cognitive decline in one patient for 15 years and 18 years in the other. In fact, one of the patients’ thinking skills got a little better.

Wisniewski said, “What’s good for the heart is good for the brain.”

This article was originally published on NBCNews.com