Risk factors for idiopathic dystonia in Queensland, Australia.

It is currently hypothesised that a combination of genetic and environmental factors underlies the development of idiopathic isolated dystonia (IID). In this study, we examined several possible environmental or other non-genetic factors that may influence the risk for IID in Queensland, Australia. We surveyed several environmental exposures, lifestyle factors, medical and family histories to investigate potential risk factors for IID. Associations between putative risk factors and IID were assessed using a total of 184 dystonia patients and 1048 neurologically-normal control subjects sampled from Queensland between 2005 and 2012. Our analyses revealed that anxiety disorders, depression, tremor, cigarette smoking and head injuries with a loss of consciousness were associated with increased risk for IID (p<0.05), all of which remained statistically significant following an adjustment for multiple hypothesis testing except for depression. We also observed that the risk for dystonia increased with higher cigarette smoking pack-year quartiles in our analyses. Our results suggest possible environmental factors that influence the development of IID and complement the findings of similar dystonia risk factor studies. Further investigation defining the environmental and other non-genetic risk factors for IID may provide insight into the development of the disorder in genetically-susceptible individuals.