The next time someone compliments you on your firm handshake, you can smile to yourself, knowing that's a sign of good brain health as well.

At least that's the word from a new study published in the medical journal Schizophrenia Bulletin. It found that muscular strength, when measured by handgrip, is an indicator of the person's overall brain health.

"When taking multiple factors into account such as age, gender, bodyweight and education, our study confirms that people who are stronger do indeed tend to have better functioning brains," says lead author Joseph Firth, a research fellow at NICM Health Research Institute at Western Sydney University, in a statement.

Get a grip

A woman squeezing a stress ball Maximum grip strength was 'positively and significantly related' to visual memory, reaction time, reasoning, number memory and prospective memory,' the study authors write. (Photo: Chutima Chaochaiya/Shutterstock)

Firth and his colleagues used data collected through the U.K. Biobank between 2007 and 2010. Residents in 9.2 million homes were invited to the study, and 502,664 adults between 37 and 73 years of age from across the U.K. eventually participated. (Some with neurological disorders that impaired cognitive functions were removed from the final results, however, as were those unable to complete the tests required of the study. This resulted in researchers collecting data from 475,397 participants.)

Participants first had their grip strength measured, giving a single squeeze on a hand dynamometer with each hand and then declaring to a researcher which is their dominant hand. The score for that hand was used in the later analyses; for people who declared themselves to be ambidextrous, whichever hand registered the higher score in the grip test was used.

From there, the participants completed a 15-minute battery of cognitive exams designed by the U.K. Biobank to allow for population-wide testing without a researcher present. The five tests consisted of sequentially matching cards, solving verbal and numerical logic puzzles in two minutes, recalling a string of numbers, playing a brief round of the card game concentration, and remembering to act on a particular instruction given earlier in the exam period. Each test measured a particular cognitive domain: reaction time, reasoning, numeric memory, visuo-spatial memory and prospective memory, respectively.

Brawn and brain

woman climbing a wall The study suggests strength training may offer cognitive benefits for people who suffer from mental health problems, although its authors say more research is needed. (Photo: Poprotskiy Alexey/Shutterstock)

Strong-gripped participants younger and older than 55 performed consistently well across the cognitive tests, a good sign for this sort of research. Similar studies have often focused on aging populations, so the new findings — which seem to confirm that some kind of connection between handgrip strength and brain health exists across age groups — are encouraging.

As for why this particular study was published in a journal called Schizophrenia Bulletin, researchers also gathered data from 1,162 individuals with schizophrenia using the same methodology. While the study lacked statistical significance in regards to these results, the researchers note that they still found a correlation between handgrip strength and cognitive abilities, at least in regard to reaction time and visuospatial memory tests.

"Our research has shown that the connections between muscular strength and brain functioning also exist in people experiencing schizophrenia, major depression and bipolar disorder — all of which can interfere with regular brain functioning," Firth said. "This raises the strong possibility that weight-training exercises could actually improve both the physical and mental functioning of people with these conditions."

The next step, according to Firth, is to more directly test if the ways we make our bodies stronger can make our brains stronger, too: "Really, what we need now, are more studies to test if we can actually make our brains healthier by doing things which make our muscles stronger — such as weight training."