Vitamin D is known to benefit our health by regulating the amount of calcium and phosphate in the body - which helps keep our bones and teeth healthy. But new research suggests that for people with Parkinson's disease, the vitamin may help prevent or delay the onset of cognitive impairment and depressive symptoms.
According to the Parkinson's Disease Foundation, around 60% of patients with Parkinson's disease suffer from depression, and the research team, including Dr. Amie L. Peterson of the Oregon Health and Sciences University, states that around 30% have cognitive impairment or dementia.
In the background of their study, findings of which are published in the Journal of Parkinson's Disease, the investigators say previous research has found that vitamin D appears to play an important role in the central nervous system, assisting with neurodevelopment and stabilizing mitochondrial function.
With this in mind, the investigators decided to see how vitamin D levels affected the cognitive impairment and mood of 286 patients with Parkinson's disease.
All patients were tested for measures of global cognitive function, verbal memory, semantic verbal fluency, executive function and depression. The researchers also measured their vitamin D levels the same day.
Higher vitamin D levels 'beneficial' before dementia onset
The researchers found that 225 patients suffered from symptoms of dementia, while 61 did not.
For all patients, those who had higher levels of vitamin D were better able to recall names and experienced a shorter delay in remembering items on a verbal learning test.
But on dividing the participants into dementia and non-dementia groups, higher levels of vitamin D only appeared to improve fluency and verbal learning for Parkinson's patients who were free of dementia.
Commenting on these findings, Dr. Peterson says:
"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."
The researchers also found that higher levels of vitamin D appeared to improve symptoms of depression in subjects who were free of dementia.
They note that higher vitamin D levels had no impact on depression for participants with dementia, and for the group as a whole, vitamin D levels made no difference to disease severity.
The research team points out that their study has some weaknesses. It was not able to determine causative effects of vitamin D on Parkinson's, such as whether low levels of the vitamin impact cognitive performance.
Furthermore, the study did not take into consideration whether patients were taking vitamin D supplements.
Medical News Today recently reported on a study suggesting that mothers with a high vitamin D intake during pregnancy are more likely to have children with stronger muscles.