Retirement Can Harm Your Brain. Here’s How to Keep It Healthy.

For the millions of Americans who retire each year, stopping work might seem like a well-deserved break. But it can also precipitate big changes in brain health, including an increased risk of cognitive decline and depression.

Before retiring, you’re getting up in the morning, socializing with co-workers and dealing with the mental challenges of your job, said Ross Andel, a professor at Arizona State University who studies cognitive aging and retirement. “All of a sudden, after 50 years, you lose that routine.”

There’s this idea that the body and brain adapt when they’re “no longer needed,” he added. “That’s when you see the deterioration and its natural response to inactivity.”

But retirement can also be an opportunity for improving cognitive and mental health, with newfound time to socialize and take on hobbies. And even if you have started to experience some decline, there’s strong evidence that your brain can bounce back from periods of inactivity, even in older age, said Giacomo Pasini, a professor of econometrics at Ca’ Foscari University of Venice, who studies the impact of economic policy on seniors’ mental health.

A Decline in Cognition and Mood

One analysis of more than 8,000 retirees in Europe found that people’s verbal memory (the ability to recall a set of words after a certain amount of time) generally declined faster once they retired, compared with when they were working. Another survey conducted in England showed a steep decline in verbal memory after retirement, though other skills, like abstract reasoning, were not affected.

“There’s some evidence out there that retirement may be bad for cognition, because when you retire, you don’t challenge your brain as much,” said Guglielmo Weber, a professor of econometrics at the University of Padova in Italy who worked on the Europe study.

Research has also found a link between retirement and the onset of depression. Suddenly going from a “busy work life to a lack of engagement can exacerbate feelings of worthlessness, low mood, sadness” and “severe depressive symptoms and memory loss,” said Xi Chen, an associate professor of public health at Yale University who studies aging.

The nature of your work — and how you view that work — seem to affect the risk of decline. For example, researchers think that those who worked in higher-ranking jobs may show a steeper decline than others, possibly because their identities were more strongly tied to their careers, Dr. Chen said.

The study in Europe also found that people who stopped working earlier than the standard retirement age where they lived showed less of a decline than those who stopped working later, Dr. Weber said. That could be because the people who retired earlier may not have had as mentally demanding jobs, resulting in a more gradual decline once they retired.

People who are forced to retire “due to health issues or blatant ageism,” or who face financial challenges in retirement, can see more severe effects, said Dr. Emily Fessler, an assistant professor at Weill Cornell Medicine who specializes in geriatric care.

And women may be less likely to experience a steep mental or cognitive decline, potentially because they are more likely than men to continue to socialize and spend time with family after they retire, Dr. Weber said.

The Value of Having a Plan

Retirement can be an occasion for growth instead of decline, the experts said. The key is to lay some groundwork ahead of time.

Don’t wait for retirement to plan for retirement.

“The plan cannot be, ‘I worked so hard for so long that I’m going to take this long vacation and then I’m going to figure it out,’” Dr. Andel said.

Ideally, you should introduce new mentally and physically engaging routines a couple of years before you stop working, said Dr. Alison Moore, chief of the geriatrics, gerontology and palliative care division at the University of California, San Diego. Even if you don’t start them right away, you should make the plan ahead of time. Delaying those decisions — like whether to spend half the year traveling — until after you’ve retired makes it harder to take the plunge, she said.

The goal is to “pivot from one type of daily life to another,” she said. “Being open to new experiences before you make this big life change can kind of prep you.”

Find a new sense of purpose.

“People may have felt their purpose was contributing through work, and when that’s taken away, they have to invent something else to take its place,” said John Beard, a professor of productive aging at Columbia University Medical Center. Studies suggest that people with a sense of purpose tend to experience less age-related cognitive decline.

Volunteer work, in particular, can help, Dr. Chen said. Research has found that people who regularly volunteer in retirement show slower rates of biological aging, and that they can head off cognitive decline by staying active and engaged (without the stress of full-time employment).

Commit to staying social.

It’s common for people to lose social connections during retirement, said David Richter, a professor of survey research in the department of educational science and psychology at Freie Universität Berlin. “We have rather solid proof that first social contacts are reduced, and then cognition declines,” he said.

To stave off the depression, cognitive decline and early mortality that can come with social isolation, Dr. Richter recommended that retirees replace workplace socializing with routine in-person or virtual gatherings.

Not all socializing is created equal, he added. The best activities are ones that challenge your mind and foster meaningful discussions with others; think things like book clubs.

“Listening to the radio, watching TV is not the same,” he said. “We really need to have this back and forth of a conversation.”

Try new things.

Doing something creative and novel can give you a sense of purpose and keep your brain agile. Research suggests you can practice creativity just like any other skill, said Jonathan Schooler, a distinguished professor of psychological and brain sciences at the University of California, Santa Barbara. That could mean writing for a few minutes every day or attempting an adventurous new recipe for dinner. Regular exercise is critical for brain health as you age, so you could also consider trying a new type of fitness class.

Creativity can also boost a person’s sense of “meaning,” Dr. Schooler added. “There is great evidence that finding meaning in life gives one a great personal satisfaction.”