Vitamin D Levels, APOE Allele, and MRI Volumetry Assessed by NeuroQuant in Norwegian Adults with Cognitive Symptoms

Allele epsilon 4 of the apolipoprotein (APOE epsilon 4) gene is the strongest known genetic risk factor for late-onset sporadic Alzheimer's disease. A possible relationship between vitamin D and APOE is not yet clear. Objective: In this exploratory, cross-sectional study, we examined the association between serum levels of 25-hydroxyvitamin D [25(OH)D] and brain volumes and the associations of both serum levels of 25(OH)D and APOE polymorphism to brain volumes in 127 persons (mean age 66 years) with cognitive symptoms. Methods: All subjects were examined with fully automated software for MRI volumetry, NeuroQuant. Results: After adjustment for relevant covariates, higher serum 25(OH)D levels were associated with greater volumes of cortical gray matter on both left (p = 0.02) and right (p = 0.04) sides. When both 25(OH)D levels and APOE genotype were used as the main covariates, no significant associations were found between vitamin D level and brain volume in any of the 11 brain regions. In adjusted models, only homozygous but not heterozygous APOE epsilon 4 allele carriers had significantly larger inferior lateral ventricles (p = 0.003) and smaller hippocampal volume (p = 0.035) than those without epsilon 4. Homozygous APOE epsilon 4 carriers also had significantly higher vitamin D levels (p = 0.009) compared to persons without the APOE epsilon 4 allele. Conclusion: Higher vitamin D levels might have a preserving effect on cortical grey matter volume.

Automated summary

The study explored the relationship between serum 25(OH)D levels and brain volumes, finding higher vitamin D levels were associated with greater cortical grey matter volume. Brain structural changes in homozygous APOE ε4 carriers were related to vitamin D levels.