Possible risk factors for primary adult onset dystonia: a case-control investigation by the Italian Movement Disorders Study Group

OBJECTIVES—Little is known about the aetiology ofidiopathic adult onset dystonia. The Italian Movement Disorders StudyGroup promoted a case-control study on some hypothetical risk factorsincluding past medical events, life events, life habits, occupationalhazards, and family hystory of dystonia, parkinsonism, and tremor.
METHODS—Cases affected by idiopathic adult onsetdystonia (age at symptom onset >20 years, duration of disease >oneyear and <five years) were selected among consecutive outpatientsattending 14Italian centres. Control outpatients matched for age(±5 years), sex, and referral centre were identified amongdiagnostic categories thought to be unassociated with studyexposures. Information was obtained by a standardised questionnaireadministered by medical interviewers. Conditional logistic univariateand multivariate regression analyses were performed by a standardstatistical package.
RESULTS—Multivariate analysis on 202 cases and 202 age and sex matched control outpatients indicated that head or facialtrauma with loss of consciousness, family history of dystonia, andfamily history of postural tremor independently increased the risk of developing adult onset dystonia, whereas hypertension and cigarette smoking exerted a protective effect. The findings also suggested apositive association between local body injury—for example, previousocular diseases and neck or trunk trauma—and dystonia of the same body part.
CONCLUSIONS—The results support the idea thatenvironmental and genetic factors may both be important in theaetiology of adult onset dystonia, and suggest aetiological cluesworthy of further analytical investigation.