Study: Vitamin D may prevent dementia
Taking vitamin D supplements may help ward off dementia, according to a new, large-scale study.
Researchers at the University of Calgary are starting a national project to try to get more insight into the brain as people age.
The CAN-PROTECT project, led by Dr. Zahinoor Ismail, begins Wednesday — the same day that a new paper he co-authored shows taking vitamin D could help prevent dementia.
“We compared older adults who were on vitamin D to those who were not on vitamin D over 10 years for the rate of development of dementia,” said Ismail, a professor of psychiatry and neurology at the U of C and the University of Exeter in the United Kingdom.
The 12,000 participants in the study, published in the journal Alzheimer’s & Dementia, were part of the National Alzheimer’s Coordinating Center in the United States. They had an average age of 71 and didn’t have dementia when they signed up for it. About 37 per cent of those involved took vitamin D supplements.
“What we found was that persons who were taking vitamin D at baseline compared to those who took no vitamin D over that time developed dementia probably at a 40 per cent lower rate, so it’s quite a significant association,” Ismail said in an interview.
Researchers also found the effects were greater in women than men and in those with normal cognition than those with mild cognitive impairment, which is associated with a higher risk of getting dementia.
Ismail said that could suggest “the earlier you start, the more you can prevent progression.”
The effects of vitamin D were also significantly greater in people who did not carry the APOEe4 gene, known to present a higher risk for Alzheimer’s dementia, compared to non-carriers. The authors suggest that people who carry the APOEe4 gene absorb vitamin D better from their intestine, which might reduce the vitamin D supplementation effect. However, no blood levels were drawn to test this hypothesis.
Previous research has found that low levels of vitamin D are linked to higher dementia risk. Vitamin D is involved in the clearance of amyloid in the brain, the accumulation of which is one of the hallmarks of Alzheimer’s disease. Studies have also found that vitamin D may provide help to protect the brain against build-up of tau, another protein involved in the development of dementia.
Ismail said he and others are now working to get Canadian-specific data through the national research project. It is modelled after an online platform called PROTECT, based at the University of Exeter, that asks annual questionnaires on detailed lifestyle factors combined with some cognitive testing to determine what keeps the brain sharp later in life.
The Canadian project, he said, will build on the results of the vitamin D study with U.S. participants.
“We’re farther north and there are other variables that we want to measure more closely regarding your ethnocultural group, whether you live in a sunny place or not, whether you go south for the winter,” said Ismail.
“There are many other variables that we’d like to know about that would allow us to refine our understanding even more.”
The study will be conducted online and researchers hope to recruit about 10,000 participants from across Canada.
“People sign up along with a study partner — someone who knows them well for at least five years — and then there are annual measures of health and wellness, risk and resilience, cognition, behaviour function,” he said.
The study will run for 20 years, and he said people from all areas and backgrounds can join at any time.
“It’s a way to really get an understanding of brain aging over time,” said Ismail, noting researchers will look closer at vitamin D and many other factors that could affect the brain.
The research, he added, will also include an examination of people who care for those with dementia — family caregivers as well as nurses, occupational therapists and others who work in a care-giving role.
Co-author Dr Byron Creese, at the University of Exeter, also said: “Preventing dementia or even delaying its onset is vitally important given the growing numbers of people affected. The link with vitamin D in this study suggests that taking vitamin D supplements may be beneficial in preventing or delaying dementia, but we now need clinical trials to confirm whether this is really the case. The ongoing Vitamin D study at the University of Exeter is exploring this issue further by randomly assigning participants to either take vitamin D or placebo and examining changes in memory and thinking tests over time.”
Part of the article was reported by Global News.