We came across a post on X which claims that brushing your teeth with your non-dominant hand (your “wrong” hand) can prevent dementia. Within 24 hours, the post garnered over 130,000 views.
The post was published by Dexerto, an entertainment and gaming news outlet, with a link to an article on its website. The article cites a viral TikTok video by a researcher named Neal K. Shah, which has since garnered over 893,000 views. A separate version of the same video shared on Facebook has since accumulated around 8.4 million views.
Dementia is a syndrome caused by diseases that damage the brain over time, leading to deterioration in memory, thinking and the ability to perform daily activities beyond normal ageing. Alzheimer’s disease is the most common form, accounting for around 60 to 70% of cases.
According to the Well-being of the Singapore Elderly (WiSE) study by the Institute of Mental Health in 2023, approximately one in eleven adults aged 60 and above in Singapore lives with dementia. This figure rises sharply with age, with approximately one in two people aged 85 and above diagnosed with the condition. The Ministry of Health has projected that the number of persons living with dementia in Singapore could reach 152,000 by 2030. Given Singapore’s growing concerns about dementia, claims offering simple preventive habits carry significant appeal, and we decided to take a closer look at what the science actually says.
What does the article say?
The Dexerto article, published on 30 June 2026, carries the headline: “Researcher reveals why using your ‘wrong hand’ to do tasks can prevent dementia.” It describes Shah as a researcher funded by the National Institute of Health in the United States and presents his TikTok tip as scientifically grounded advice for people looking to reduce their risk of dementia.
The article explains that switching to the non-dominant hand for automatic tasks such as brushing teeth, forces the brain to develop new strategies to complete the same task, activating areas responsible for planning, coordination and focus. It states that this encourages neuroplasticity, the brain’s ability to reorganise and strengthen connections between brain cells, and builds cognitive reserve, the brain’s ability to continue functioning despite age-related changes or early neurodegeneration.
The article, however, includes a caveat that contradicts its headline, stating “[w]hile habits like these may support long-term brain health, they are not a proven way to prevent dementia or Alzheimer’s disease.”
What does Shah actually claim?
In the video, Shah does not claim that brushing teeth with the wrong hand prevents dementia, contrary to Dexerto’s headline. His argument is that the habit builds cognitive reserve, the brain’s ability to absorb damage from ageing or early neurodegeneration without showing clinical symptoms.
Shah explains that brushing teeth with the dominant hand puts the brain on autopilot, executing a familiar motor pattern with minimal cognitive effort. Switching to the non-dominant hand forces the brain to recruit new motor pathways, activating the prefrontal cortex to manage an unfamiliar task. Shah argues that with repetition, these new neural connections strengthen into “actual structural changes in brain tissue”, in a process he describes as neuroplasticity in action.
In sum, Shah claims that two minutes of brushing with the wrong hand every morning builds cognitive reserve and protects the brain against age-related decline. However, Dexerto’s headline takes Shah’s claim a step further, framing it as a dementia prevention strategy that Shah himself never asserts.
The article’s description of Shah as an “NIH-funded principal investigator” also warrants closer examination. While technically accurate, the framing implies a level of institutional endorsement that does not extend to this specific claim. Shah’s NIH-funded work, as publicly documented, relates to AI tools for dementia care delivery, specifically, an AI-powered caregiver training application developed at Johns Hopkins University, rather than neuroscience research. Shah is also not a medical doctor.
Can brushing teeth with your non-dominant hand really help?
Shah does not cite a specific study at any point in the video. However, his references to neuroscience mechanisms are not without basis. The claim that switching hands activates different neural pathways is well-established. More recently, a 2023 study by researchers from Japan’s National Institute of Advanced Industrial Science and Technology found that tasks done with the non-dominant hand may help stimulate interhemispheric interactions between the left and right brain hemispheres.
However, Shah’s claim that two minutes daily of using your non-dominant hand leads to actual structural changes in brain tissue appears to overstate what the research supports. Structural changes in the brain, where the physical architecture of brain tissue is altered, are distinct from the brain simply becoming more active during a task.
For instance, a 2018 critical review led by researchers in Australia, examining 25 studies on training-dependent structural neuroplasticity (changes in the physical structure of the brain resulting from repeated practice or rehabilitation) in patients recovering from brain injuries, found that even in clinical rehabilitation settings, structural brain changes required sustained, intensive programmes incorporating varied exercises over extended periods, verified using brain imaging. In addition, a 2025 systematic review published by researchers from the University of Coimbra, Portugal, found that measuring neuroplasticity reliably remains a significant challenge, as most imaging techniques can only capture indirect indicators of brain change rather than direct molecular evidence. The review explicitly calls for more objective and direct criteria in plasticity studies.
Furthermore, a 2025 review published by researchers in South Korea, synthesising longitudinal cohort studies on cognitive reserve in ageing and Alzheimer’s disease, found that a variety of factors led to higher cognitive reserve. This might include occupational complexity, bilingualism, and engagement in enriching leisure activities. While higher cognitive reserve was associated with delayed onset of cognitive impairment and reduced dementia risk, the study pointed to sustained, varied engagement as the mechanism through which cognitive reserve is built, not just one habit.
Notably, current research has not identified any measures that have been proven to prevent dementia.
Hence, we find the claim that brushing your teeth with your non-dominant hand can prevent dementia to be misleading and false, as it overstates what current research supports.
When encountering health claims, it is important to look beyond attention-grabbing headlines. Headlines may overstate the implications of a study, even where the article itself includes important caveats about the limits of the research.
