Conjugal Parkinsonism and Parkinson disease: a case series with environmental risk factor analysis

PD occurring in married couples, "conjugal PD" represents a unique opportunity to study environmental risk factors for PD due to the shared environment. This retrospective study of non-related married individuals who both presented to the Washington University Movement Disorders Center between 1994 and 2005 investigated the clinical presentation, therapy response, and disease course in conjugal PD subjects. In addition, an occupational, residential, and environmental survey was administered to elucidate potential shared environmental risk factors. Eighteen married subjects had a clinical picture suggestive of idiopathic Parkinson disease. Average age of motor symptom onset was 66.1 (+/-6.22) years in women, 63.4 (+/-7.87) years in men. Subjects cohabitated an average of 39.9 years prior to motor symptom onset in the first affected spouse and an average of nine years elapsed prior to symptom onset in their partner. Disease course in conjugal pairs varied substantially. Seventeen out of eighteen subjects reported at least one environmental exposure of interest. Concordant exposures were residential, non-occupational pesticide and heavy metal exposure, each reported by 77.8% (7/9) of couples. Multiple exposures were reported by 88.9% (16/18) of subjects, most often residential agricultural chemical and heavy metal in combination. This case series of conjugal PD suggests that combined residential exposures may be important in the pathogenesis of idiopathic PD. Larger conjugal PD studies may permit stratification of concordant environmental exposures to determine dose responsiveness and relative contributions to PD risk.