Parkinson's disease

Abstract

We studied the relative etiologic importance upon the development of Parkinson's disease (PD) of occupational exposure to herbicides and other compounds, ionizing radiation exposure, family history of PD and essential tremor, smoking, and history of various viral and other medical conditions. We identified patients (n = 130) with neurologist-confirmed idiopathic PD through contacts with Calgary general hospitals, long-term care facilities, neurologists, the Movement Disorder Clinic, and the Parkinson's Society of Southern Alberta, and selected two matched (by sex and age +/- 2.5 years) community controls for each case by random digit dialing. We obtained lifetime work, chemical, radiation, medical, and smoking exposure histories and family histories of PD and essential tremor by personal interviews, and analyzed the data using conditional logistic regression for matched sets. After controlling for potential confounding and interaction between the exposure variables, using multivariate statistical methods, having a family history of PD was the strongest predictor of PD risk, followed by head trauma and then occupational herbicide use. Cases and controls did not differ in their previous exposures to smoking or ionizing radiation; family history of essential tremor; work-related contact with aluminum, carbon monoxide, cyanide, manganese, mercury, or mineral oils; or history of arteriosclerosis, chicken pox, encephalitis, hypertension, hypotension, measles, mumps, rubella, or Spanish flu. These results support the hypothesis of a multifactorial etiology for PD, probably involving genetic, environmental, trauma, and possibly other factors.

Epidemiology and etiology of Parkinson’s disease: a review of the evidence

“…Four case-control studies found no association between exposure to manganese and PD [132,292,300,317]. Similarly, one small study (29 cases) found no association between serum or urinary levels of manganese and PD [384].…”

“…An early case-control study [127] reported higher frequency of hypertension among PD cases compared to controls, although no p value was provided. Six other case-control studies [132,142,303,358,409,466] found no association between selfreported hypertension and PD, one study found lower risk of PD associated with hypertension in univariate analyses, but when adjusting for smoking and other variables, the association did not persist [631]. Another case-control study reported increased PD risk associated with hypertension in women (OR 1.62, 95% CI 1.00-2.62) but not in men [540].…”

“…Studies that assessed occupational exposure to mercury [132,154,382] and zinc [154,382] found no relation to PD.…”

“…Whilst most studies found similar antibody levels in cases and controls, one study observed higher antibody levels for herpes simplex [538], while another study found lower antibody levels for herpes simplex, rubella and measles [539]. Similarly, studies that examined self-reported history of influenza [132,292,344] or other viral infections [142,411,540] generally reported no association with PD. A case-control study nested within the Harvard Alumni cohort, USA [541] found reduced PD risk associated with measles infection (OR 0.53, 95% CI 0.31-0.93) and another case-control study [411] found increased PD risk associated with diphtheria (OR 2.3, 95% CI 1.2-4.7) and croup (OR 4.1, 95% CI 1.1-16.1).…”

“…Only a minority of studies adjusted for possible confounders such as smoking, and different definitions of head trauma make comparisons between studies difficult. Of 22 case-control studies, 9 reported increased risk of PD following head trauma [131,132,300,310,312,355,[621][622][623] with ORs ranging between 1.4 and 11.7. The remaining 13 studies found no association [140-142, 145, 147, 154, 156, 296, 309, 315, 358, 411, 420].…”