Researchers analyzed participants of the Rush Memory and Aging Project (MAP) – an ongoing longitudinal study that aims to identify risk factors for Alzheimer’s disease and other cognitive decline disorders – before and after death to see how their vitamin D levels affected cognitive function in later life. years.
Free of known dementia at the time of enrollment, all MAP participants have agreed to participate in annual assessments and organ donation upon death. In this study, the average age of participants was 92 years at the time of death.
Total serum vitamin D levels [25(OH)D] and global cognitive function were assessed ante mortem, while vitamin D3, 25(OH)D3 and 1,25(OH)D3 (the active form of vitamin D3) were measured in four brain regions ( the medio-temporal cortex, the cortex, cerebellum and white matter of the anterior watershed) post-mortem.
The main form of vitamin D3 found in the brain (and therefore the form the researchers focused on in their analysis) was 25(OH)D3. It should be noted that there are two types of vitamin D – D2 and D3 – and brain levels of vitamin D2 (the form found in most fortified food sources) were not measured in this study.
Ashley Jordan Ferira, Ph.D., RDN, vice president of scientific affairs at mindbodygreen, explains this limitation: “Vitamin D3 is found in animal sources and key algae and lichens, while vitamin D2 comes from plant sources. such as yeast and irradiated fungi.If your healthcare provider accidentally measured serum 25(OH)D3, but you were regrowing irradiated fungi or a vitamin D2 supplement, your lab results would not reflect not your input image.”
Although the results of this study are still relevant to dementia research, it is important to keep this discrepancy in mind when reading the results.