Scientists are trying to discover a link between Parkinson’s disease and low blood levels of vitamin D. A U.S. team found that 55 % of patients with Parkinson’s had low levels of vitamin D as compared to 36 % of healthy elderly people. Following this researchers at Emory University are trying to find out if the vitamin deficiency is a cause or the result of having Parkinson's.

Previous studies have shown that the substantia nigra, which is the part of the brain affected most by Parkinson's, has high levels of the vitamin D receptor, which suggests vitamin D may be important for normal functions of these cells. Nerve cells in several parts of the brain are affected in Parkinson’s, particularly those that use the chemical messenger dopamine to control movement. Characterized by stiffness, tremors and slowness in movement, Parkinson’s can be treated with oral replacement of dopamine.

 In the study100 Parkinson's disease patients, 100 Alzheimer's disease patients, and 100 healthy adults all of a similar age and economic circumstance were studied. Blood samples showed vitamin D insufficiency in 55% of the Parkinson's disease patients, 41% of the Alzheimer's patients and 36% of the healthy participants. Levels of vitamin D that were so low that they could be termed as ‘deficient’ were found in 23 % of the Parkinson group, 16 % in the Alzheimer’s group and 10 % in the healthy group.

The researchers said the study group was from the South West of the U.S. which is a sunny and warm area and makes the findings striking. Researcher Dr Marian Evatt said: "We found that vitamin D insufficiency may have a unique association with Parkinson's, which is intriguing and warrants further investigation." Scientists are testing whether vitamin D supplements can reduce symptoms of Parkinson's disease.

Dr Kieran Breen, director of research, Parkinson’s Disease Society said: "Further research is required to determine at what stage the deficiency in vitamin levels occur in the brains of people with Parkinson's and whether the provision of a dietary supplement, or increased exposure to sunlight may help alleviate symptoms or have an affect on the rate of the condition's progression. This would help us answer the question as to whether the decrease in vitamin D levels in Parkinson’s is a cause or effect of the condition."

The study appeared in the journal Archives of Neurology.