Why you should be brushing your teeth with your left hand to prevent dementia

The secret to a better brain workout might already be sitting in your bathroom.

That matters as more and more people experience memory concerns. About one in 10 adults ages 45 and older report worsening memory loss or cognitive decline, according to the CDC, and many more are caring for someone experiencing cognitive challenges.

There are plenty of brain-training apps designed to challenge the mind, but there’s also another simple trick that costs nothing and takes about two minutes: Brushing your teeth with your non-dominant — in most cases, your left — hand.

Neal K. Shah, an NIH-funded principal investigator, shared the idea in a TikTok video, encouraging people to use their “wrong hand” during everyday tasks.

For most adults, brushing one’s teeth is automatic. After years of practice, your brain has the routine mapped out, so your muscles know what to do with little conscious thought, explained Shah.

But when you switch hands, your brain has to pay closer attention and create a new strategy.

That extra challenge activates different areas of the brain involved in planning, coordination and focus. Over time, repeating unfamiliar tasks can strengthen connections between brain cells, a process known as neuroplasticity.

In short, your brain is constantly adapting based on what you do, and just like a muscle responds to new exercises, the brain responds to new experiences.

Shah pointed out that cross-lateral movements — using the opposite side of the body from what we normally use — can engage broader brain networks involved in attention, memory and coordination.

This can be especially important as we age, he added.

People with greater cognitive reserve — the brain’s ability to keep functioning despite normal aging or changes associated with conditions like dementia and Alzheimer’s — may be able to tolerate more brain changes before experiencing noticeable symptoms.

Building that reserve doesn’t require expensive treatment or a fancy program. Learning new skills, staying socially engaged, exercising and challenging your brain in new ways can all contribute.

In fact, research has found that learning another language can make a major difference in long-term brain health.

“What is emerging consistently is that older adults who speak more than one language have clear advantages against dementia,” Natalie Phillips, a psychology professor at Concordia University in Montreal, told New Scientist last year.

“Bilingualism changes the way you cope with an increasingly compromised brain,” she continued. “It doesn’t prevent dementia, it holds back the flood. When bilingual people eventually show cognitive problems, they decline faster, but it starts later.”

Another study out of Japan found that older adults who cooking at home might lower their risk of dementia by anywhere from 30% to almost 70% — with novice cooks who were less skilled (and thus challenging themselves more) reaping the biggest benefit.