The findings, published in the Journal of Parkinson’s Disease, point to the possibility that early intervention could delay or prevent the onset of cognitive impairment and depression, according to the researchers.
They add that the effect was even more pronounced in patients who did not suffer from dementia.
“About 30 percent of persons with PD suffer from cognitive impairment and dementia, and dementia is associated with nursing home placement and shortened life expectancy,” said Amie L. Peterson, M.D., of the Oregon Health and Sciences University.
“We know mild cognitive impairment may predict the future development of dementia. Intervening in the development of dementia has the potential to improve morbidity and mortality in persons with PD.”
In the analysis, which was an add-on study to an ongoing study of neuropsychiatric function in people with PD, 286 Parkinson’s patients were given a battery of tests measuring global cognitive function, verbal memory, semantic verbal fluency, executive function, and depression.
On the same day, serum 25-hydroxy Vitamin D levels were measured.
Of the 286 subjects, 61 were considered to be suffering dementia by a consensus panel based on the Diagnostic and Statistical Manual of the American Psychiatric Association (4th edition), the researchers noted.
The researchers found that, for the entire group, higher levels of Vitamin D3 were associated with greater fluency for naming vegetables and animals and immediate and delayed recall on a verbal learning test.
The researchers also discovered that for those patients who weren’t suffering from dementia, those with higher levels of Vitamin D did better on the fluency and verbal learning assessments.
“The fact that the relationship between Vitamin D concentration and cognitive performance seemed more robust in the non-demented subset suggests that earlier intervention before dementia is present may be more effective,” said Peterson.
The analysis also found a link between lower levels of Vitamin D and depression, for the entire group, as well as for those patients not suffering from dementia. There was no “significant relationship” for those who were demented, according to the researchers.
The researchers noted that the study did not determine the cause of the link. For example, does low Vitamin D affect cognitive performance, or are people with more advanced Parkinson’s and worse cognition less ambulatory, which means they get less sun exposure, and subsequently have lower Vitamin D levels?
The study also did not consider if patients were taking Vitamin D supplements, the researchers noted.
Source: IOS Press