People with Parkinson’s disease who have higher levels of vitamin D in blood are less likely to experience their cognitive impairment or dementia, a new study suggests.
The results provide support for future research to test whether vitamin D supplements could reduce the risk of cognitive problems for Parkinson’s patients.
The study, “Correlation between serum 25(OH)D and cognitive impairment in Parkinson’s disease,” was published in the Journal of Clinical Neuroscience.
Vitamin D plays a number of important roles, including to help regulate calcium levels and modulate nervous system activity. Prior research has linked low levels to an increased risk of falls, depression, and sleep problems in people with Parkinson’s.
Researchers in China analyzed possible connections between cognitive outcomes and levels of serum 25(OH)D, a form of the vitamin that’s easily detectable in blood.
The study enrolled 112 people with Parkinson’s at the Affiliated Hospital of Xuzhou Medical University, China. A group of 70 people with no known health problems were included as controls. In both groups, slightly more than half the participants were male, and the average age was in the mid-60s.
Cognition was assessed with the Montreal cognitive assessment (MoCA), which is used to test for dementia. Based on standard criteria, Parkinson’s patients were divided into those with normal cognition, those with mild cognitive impairment (MCI), and those with Parkinson’s disease dementia (PDD).
“This is one of the few studies investigating the association between serum 25(OH)D and cognitive impairment in Chinese [Parkinson’s] patients,” the researchers wrote.
They found that average vitamin D levels were significantly higher in the healthy controls than the Parkinson’s patients: 56.54 vs. 45.86 nanomoles per liter (nmol/L). Among the Parkinson’s patients, average levels were highest in those with normal cognition (53.67 nmol/L), followed by those with MCI (44.57 nmol/L) and then PDD (36.53 nmol/L).
Higher levels of serum 25(OH)D were also significantly associated with better MoCA scores. This association remained significant even after statistical adjustments for age, gender, body mass index (BMI), years of education, and sunlight exposure.
Researchers found that assessing vitamin D levels could be used to accurately predict cognitive impairment risks. These results suggest that “low serum 25(OH)D may be involved in the occurrence and development of cognitive impairment in [Parkinson’s] patients,” the researchers wrote.
The scientists did emphasize that, because of the way the study was designed, it’s not possible to make any definitive conclusions about cause and effect with regard to vitamin D and cognition in Parkinson’s. They said further research is needed to see whether supplements may protect against cognitive problems in Parkinson’s.
Although efficacy remains to be proven, “long-term vitamin D supplementation carries a low risk and many possible benefits for patients,” the researchers concluded. “Therefore, evaluating vitamin D for patients with [Parkinson’s] and supplementing vitamin D for deficient patients are worth trying.”