OBI's CEO and Scientific Director Featured in The Weather Network on Vitamin D and Dementia Risk
May 19, 2026
Ontario Brain Institute (OBI) CEO and Scientific Director Dr. Tom Mikkelsen was recently featured in The Weather Network, offering expert commentary on a new study exploring the link between vitamin D levels in midlife and long-term brain health.
Published April 1, 2026 in Neurology® Open Access, an official journal of the American Academy of Neurology, the study followed nearly 800 adults over 16 years and found that those with higher vitamin D levels in their 30s and 40s had lower levels of tau protein in their brains later in life, a key biomarker linked to Alzheimer's disease and other forms of dementia. Lead author Dr. Martin David Mulligan of the University of Galway noted that midlife is a particularly important window for intervention, where risk factor modification can have the greatest impact on long-term outcomes.
In the feature, Dr. Mikkelsen offered a clear explanation of how tau protein damages the brain: abnormal protein clumps form within neurons, interfering with their function, ultimately causing cell death, and contributing to cognitive decline.
While the findings are promising, the study demonstrates an association rather than direct causation, and further research is needed before firm conclusions can be drawn.
What this means for Canadians
This research carries particular relevance in Canada, where an estimated 1 in 5 Canadians have low vitamin D levels, largely due to long winters with limited sunlight and reduced time outdoors. Maintaining healthy levels doesn't have to be complicated: getting outside safely when you can, even in winter, makes a difference. Year-round, vitamin D-rich foods such as fatty fish (salmon, sardines), fortified dairy or plant milks, and egg yolks can also help. A routine blood test can confirm whether your levels need attention, and a doctor can advise on supplements if needed.
Vitamin D is one of several lifestyle factors emerging as potentially relevant to long-term brain health. Alongside findings like these, OBI's Physical Activity and Alzheimer's Disease Toolkit and brain health tips highlight other evidence-informed ways to support a healthy brain across the lifespan. Together, they reflect a growing understanding that dementia risk is not inevitable, and that the choices we make in midlife can matter decades later.
OBI supports dementia research through initiatives including the Canadian Dementia Registry and brain health datasets through Brain-CODE, Ontario's neuroinformatics platform that enables researchers to connect and analyze brain health data at scale. This work helps build the evidence base for prevention strategies like those explored in this research, and reflects OBI's commitment to translating science into accessible knowledge for Canadians.
Read the full Weather Network feature: Could sunshine reduce your dementia risk? Here's what a new study says
Image courtesy of The Weather Network