For many older workers, advancing age brings an inevitable and often subtle erosion of their reasoning abilities. Suddenly, employees who once were a perfect fit for their jobs might begin to feel overwhelmed.

That’s not only bad news for someone’s performance, it also might be bad for their health.

A study published in the Journal of Occupational Health Psychology found that older employees had fewer health issues when their reasoning abilities matched their job demands compared with those whose mental skills were in decline. This is a critical issue with more Americans staying in the workforce longer and as baby boomers increasingly enter their golden years. One estimate says the number of Americans over 60 might grow up to 20 percent by 2050.

The research examined a group of nearly 400 people taking part in the Cognition and Aging in the USA survey who were quizzed about their jobs and tested on their mental acuity. Their average age was 61 years.

Researchers found that those employees faced with the prospect of declining cognitive ability that left them struggling at work often retired early. One reason might be due to accumulated strain and stress.

The lesson here isn’t that people who can’t handle their office duties should be out of a job. The study noted employers benefit from the experience of older workers, who can often serve as mentors to younger colleagues.

Instead, scientists said, jobs might be better designed to complement the skills of these workers, keeping them healthier and in their careers longer.

Of course, not everybody retires because work becomes too challenging. Some might just want to spend more time with the grandkids.