Increased iron may protect against Parkinson’s disease
INCREASED serum iron levels may be associated with a decreased risk of developing Parkinson’s disease, a study has found.
However, the suggestion that increased serum iron levels may have a protective effect against the disease has left experts divided.
A group of international scientists, including researchers from Queensland Institute of Medical Research, estimated the effect of iron levels on the risk of the disease using three polymorphisms in two iron transport genes, HFE and TMPRSS6.
They found that for every 10μg/dl increase in serum iron there was a 3% relative reduction in the risk of Parkinson’s disease.
For each polymorphism, they performed a meta-analysis of studies investigating the genetic effect on iron levels, which included almost 22,000 people from Europe and Australia, and a meta-analysis of studies investigating the genetic effect on the risk of Parkinson’s disease, which included a total of 20,809 people with Parkinson’s disease and 88,892 controls from Europe and North America.
They then performed three separate Mendelian randomisation analyses to estimate the effect of iron on Parkinson's disease for the three polymorphisms.
The authors said having higher iron levels in the brain was generally thought of as a risk factor for Parkinson’s disease but suggested that disrupted iron metabolism may be an important factor in the pathogenesis of the disease.
Professor Ashley Ian Bush, director of the Oxidation Biology Unit at The Florey Institute of Neuroscience and Mental Health, described the findings as “extremely important and exciting”.
“It uses the genetics of the iron regulatory pathway to establish that an abnormality of iron regulation causes Parkinson's disease,” he said.
“Since iron accumulates in the affected regions of the brain in Parkinson’s disease, these findings indicate that the inability to move iron from the brain into the blood can cause the disease.
“This does not mean that being exposed to iron causes the disease, since, indeed, iron is needed for health. But these results tell us that a treatment that can assist in moving the iron in brain tissue back into the blood might be a disease-modifying therapy.”
But Professor George Mellick, a clinical neuroscientist at Griffith University, said the results needed to be put into perspective.
“At face value they showed that people who carry genes that slightly increase serum iron levels are at very slightly reduced risk for Parkinson’s disease,” he said.
“It will also be very important to look at the relationship between the serum and the brain iron levels – because increased iron in the brain is generally considered to be bad.
“Working out what the mechanisms are leading to these findings will be important before people consider introducing iron supplements as a treatment in patients.”
PLOS Medicine 2013; online 4 June