MONDAY, Oct. 13 (HealthDay News) -- Parkinson's disease patients are more likely than healthy people or Alzheimer's patients to have vitamin D deficiency, say researchers from the Emory University School of Medicine in Atlanta. They compared vitamin D levels in 100 Parkinson's patients, 97 Alzheimer's patients, and 99 healthy people matched for age and other factors. "Significantly more patients with Parkinson's disease [55 percent] had insufficient vitamin D than did controls [36 percent] or patients with Alzheimer's disease [41 percent]," the researchers wrote. The average vitamin D concentration among Parkinson's patients was 31.9 nanograms per milliliter, compared with 34.8 nanograms among Alzheimer's patients, and 37 nanograms among healthy people. The study was published in the October issue of theArchives of Neurology. "These findings support the previously suggested need for further studies to assess what contribution a low 25 (OH)D [a measure of blood vitamin D levels] concentration adds to the risk of developing Parkinson's disease [vs. other neurodegenerative disorders] and to determine whether correction of vitamin D insufficiency and deficiency will improve motor or non-motor symptoms in Parkinson's disease," the study authors concluded. "Finally, the finding of a high incidence of vitamin D deficiency in the Parkinson's disease and other cohorts highlights the importance of routinely checking the level of 25(OH)D, particularly in elderly patients, since deficiency is strongly associated with a higher incidence of osteoporosis, falls and hip fractures and has been associated with a higher incidence of several forms of cancer and autoimmune disorders," the researchers added.