- Higher serum vitamin D levels in midlife were associated with lower tau pathology in later years in a prospective cohort study.
- There was no association between vitamin D levels and subsequent amyloid burden.
- Modifying vitamin D in midlife may reduce dementia risk, but clinical trials are needed.
In a prospective cohort study, higher serum levels of 25-hydroxyvitamin D in midlife were associated with lower levels of later tau pathology, an Alzheimer’s disease biomarker.
At 16 years, higher vitamin D levels in midlife were associated with lower global tau PET (β = -0.022, 95% CI -0.040 to -0.004,). P=0.010) and overall tau PET deposition (β = -0.023, 95% CI -0.043 to -0.003, P=0.016), Martin Mulligan, MBCh, of the University of Galway in Ireland, and co-authors reported.
Mulligan and colleagues wrote that there was no association between vitamin D levels and subsequent amyloid PET burden. Neurology Open Access.
“This study suggests that high vitamin D levels in midlife may provide protection against pathological tau deposition in the brain, while low vitamin D may represent a potentially modifiable risk factor for healthy middle-aged individuals who want to reduce dementia risk,” said co-author Emer McGrath, MBBCh, MSc, PhD, of the University of Galway.
“However, this requires further testing in clinical trials,” McGrath said. Medpage Today.
They added, “To our knowledge, there have been no previous studies evaluating the association between serum vitamin D and neuroimaging markers of preclinical dementia.” “Notably, our study included individuals in early midlife, when there are more opportunities for risk modification.”
Low circulating vitamin D levels measured at the end of life have been linked to an increased risk of cognitive impairment. Meta-analyses have shown an association between vitamin D deficiency in older adults and both dementia And alzheimer’s disease.
Autopsy studies have also linked vitamin D levels in brain tissue to cognitive function in older adults. Other observational data has shown that people who take vitamin D supplements may be less likely to develop dementia.
Mulligan and colleagues studied Framingham Heart Study Generation 3 participants who were dementia-free at the time of brain imaging had serum vitamin D measured from 2002 to 2005, and had amyloid or tau PET scans between 2016 and 2019. Results included global tau PET deposition, overall tau and amyloid PET deposition in areas susceptible to early involvement in Alzheimer’s dementia.
In total, serum vitamin D of 793 participants was measured; 424 had amyloid PET, 369 had tau PET, and 360 had both amyloid and tau PET imaging. The findings were adjusted for age, gender, depressive symptoms and other variables.
The analysis included 435 participants. The mean age was 39.2 years and 53.8% were female. The mean time between blood sampling and PET was 16.2 years.
High levels of vitamin D were defined as more than 30 ng/mL; The low level was even lower. The mean serum vitamin D level was 38 ng/mL. One third (34%) of participants had baseline levels less than 30 ng/mL, and 5.1% (22 participants) were taking vitamin D supplements.
The researchers acknowledged several limitations of the study, including that the group was mostly Caucasian. Serum vitamin D was measured once and may change over time. Only 22 participants used vitamin D supplements at baseline, possibly due to the relatively young age of the group, hindering the ability to assess the effects of exogenous vitamin D.
McGrath said the results require validation in other studies. They reported, “Although our results support a hypothesis that modifying vitamin D levels in early to mid-life may reduce future risk of clinical dementia, this will require formal evaluation in clinical trials.”
He emphasized that the study does not prove causation. If patients feel they need vitamin D treatment, they should discuss it with their doctor, he said.
