We know exercise is important to prevent physical and mental decline in old age, but now researchers have found that it's just as important to let your brain do some heavy lifting.

A study out of the University of Exeter Medical School and Kings College London analyzed data collected from 17,000 people aged 50 and over. It found that participants who regularly engaged in word puzzles like crosswords had brain function 10 years younger than their calendar age. They were tested for attention, short-term memory accuracy, grammatical reasoning and speed.

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"Our study suggests that the frequency of use of word puzzles is related to superior cognitive function on a range of different tests, even after controlling for age, education and gender," Keith Wesnes, lead author of the study and professor of cognitive neuroscience at the University of Exeter, said to Global News.

"One likely explanation is that when engaging in such tasks, the brain has increased blood flow to certain areas, which could have beneficial effects on brain structure and integrity. The concept of 'use it or lose it' could well apply here."

Although the study has not evaluated whether it makes a difference when people take up word puzzles — if they've been doing them all their lives versus starting them in later years — it did find that those who engaged in them more frequently performed better on the evaluating tasks. Wesnes says similar findings were seen in those who engaged in number puzzles, like Sudoku.

This study could "cast doubt" on the negative responses to brain training games like Lumosity, Wesnes says.

In January 2016, Aditi Jhaveri, a consumer education specialist with the U.S. Federal Trade Commission's Bureau of Consumer Protection, published a blog post widely debunking Lumosity's "proven neuroscience research" that claims to prevent age-related memory decline.

"The FTC charged that there isn't solid science showing that Lumosity's 'brain training' games work the way they say they would," she wrote. "Playing Lumosity's games might make you better at those games, the FTC says, but that doesn't necessarily mean it will sharpen your memory or brain power in the real world."

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Wesnes says that they will be conducting a trial where participants will engage in games like those offered by Lumosity to assess whether their cognitive function improves.

"If that occurred, it would clearly debunk [the FTC's claims]," he said.

According to the Alzheimer Society of Canada, there are 564,000 Canadians living with dementia and that number will skyrocket to 937,000 in 15 years. The annual cost to the country is $10.4 billion.

In addition to word and number puzzles, exercise and diet have been shown to delay the onset of cognitive decline in old age.