Serum Parathyroid Hormone, 25-Hydroxyvitamin D, and Risk of Alzheimer's Disease : A Mendelian Randomization Study

We conducted Mendelian randomization analyses to investigate the associations of serum parathyroid hormone (S-PTH) and serum 25-hydroxyvitamin D (S-25OHD) concentrations with Alzheimer&rsquo
s disease (AD). Five and seven single nucleotide polymorphisms associated with S-PTH and S-25OHD concentrations, respectively, were used as instrumental variables. Data for AD were acquired from the International Genomics of Alzheimer&rsquo
s Project (17,008 AD cases and 37,154 controls). Genetically higher S-PTH concentrations were not associated with AD (odds ratio per standard deviation increase in S-PTH = 1.11
95% CI 0.97&ndash
1.26
p = 0.12). In contrast, all seven 25OHD-increasing alleles were inversely associated with AD and two of the associations were statistically significant (p &lt
0.05). The odds ratio of AD per genetically-predicted one standard deviation increase in S-25OHD was 0.86 (95% CI 0.78&ndash
0.94
p = 0.002). This study provides evidence that vitamin D may play a role in AD but found no significant association between S-PTH and AD.