Can crosswords and games prevent dementia?

It makes sense in principle: You exercise your muscles to make them stronger and prevent frailty and decline; shouldn’t your brain work the same way?

That premise is behind brain training websites and apps, and most likely contributed to the sale of countless Sudoku, crossword and logic puzzle books over the past two decades. It also inspired academic researchers to explore whether cognitive training really can make people smarter and even lower the risk for dementia.

But, as often happens in science, a seemingly straightforward idea is more complicated than it appears. Because the answer to “Is training your brain helpful?” depends on what type of exercises you’re doing and what benefits you’re seeking.

When psychologists conduct research on whether it’s possible to improve cognition, they mostly use computer games developed to enhance a specific aspect of how we think. Some brain training games teach people strategies to improve a skill or recognize patterns. Others gradually increase speed and difficulty to challenge the brain, said Lesley Ross, a professor of psychology at Clemson University.

Many studies have shown that playing these games can improve people’s cognitive abilities — not just on the specific task they’re working on, but related tasks, too. That “isn’t terribly surprising,” said Adrian Owen, a professor of cognitive neuroscience and imaging at Western University in Ontario, Canada, just as someone who practiced memorizing phone numbers would probably get better at remembering dates.

Evidence that playing one type of game will make you smarter overall or help you improve on a completely different kind of task is less compelling.

“Brain training works in the sense that, if you want to learn to play the violin,” you will get better if you practice the violin, Owen said. But if you learn to play the violin, “do you get any better at the trumpet? Well, the obvious answer is no.”

Some brain training companies have said that their games can help stave off cognitive decline, but research into the connection is slim. One of the few studies that has looked at this found that healthy older adults who played a game designed to improve processing speed had a 29% lower risk of dementia a decade later. People who played two other games, a memory task or a problem-solving task, also had decreased risk, but the benefit wasn’t significant compared with people who didn’t play any games.

Experts said this study suggested that brain training games have promise, but additional clinical trials are needed.

There is more research on how everyday hobbies and behaviors — like doing crossword puzzles, playing board games, reading books or newspapers, or learning another language — may protect against cognitive decline.

Several studies have suggested that the more often people engage in cognitively stimulating activities, the lower their risk for cognitive impairment or the later they receive a dementia diagnosis. For example, one found that, among adults who developed dementia, those who regularly completed crossword puzzles delayed the onset of memory decline by more than two years compared with those who didn’t.

If something is mentally challenging, “chances are that’s probably pretty good for your brain,” Ross said. But, she added, those studies of everyday activities are not randomized controlled trials — the gold standard in science and medicine — that would provide a definitive link between cognitively stimulating hobbies and a lowered risk of dementia. In other words, the current evidence only shows an association, not a direct cause and effect.

When asked why either of these types of activities, whether it’s a specially designed game or a crossword puzzle, might help the brain, experts mentioned the theory of “cognitive reserve.” The idea is the more “mental muscle” someone has built up, the more resilient they are to dementia, said Dr. Joe Verghese, the chair of the neurology department at the Stony Brook University Renaissance School of Medicine.

These activities most likely won’t prevent the brain damage that leads to dementia. But if someone does get Alzheimer’s disease, cognitive reserve “can mask the effect and delay the onset of symptoms for a few years,” Verghese said.

Support for this theory comes from research demonstrating that people with more education have a lower risk of developing dementia, said Dr. Samuel Gandy, associate director of the Mount Sinai Alzheimer’s Disease Research Center in New York City. Other studies have shown the same for people with cognitively challenging jobs. It’s possible that mentally stimulating hobbies might have a similar effect.

However, there is no way to directly measure cognitive reserve, Owen said. As a result, it’s difficult to say whether brain training games can also enhance it.

Instead, some researchers point to evidence that the games can increase and strengthen the connections between neurons, called synapses. It could be that “by having more synapses, you may be able to lose some and not notice it,” Gandy said.

The experts generally agreed that, much like physical exercise or staying socially active, cognitively stimulating activities could potentially help protect against cognitive decline, with virtually no downsides.

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When it comes to specially designed brain training games, opinions were more mixed and largely came down to whether the cost of a subscription to a brain training website was worth it. Verghese said the games deliver “cognitive stimulation in a systematic way,” making them a worthwhile expense for those who can afford it.

Owen countered that people should save their money, since many claims about improving cognition or staving off dementia “are simply not scientifically defensible.”

Perhaps Gandy summed up the debate best: “I don’t think it’ll hurt,” adding, “I can’t promise you that will help either.”

This article originally appeared in The New York Times.