Incidence of Parkinson's disease among hospital patients with methamphetamine-use disorders

Authors

  • Russell C. Callaghan PhD,

    Corresponding author
    1. Social, Epidemiological Research Department, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
    • Centre for Addiction and Mental Health, 33 Russell St., Toronto, Ontario, Canada M5S 2S1
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  • James K. Cunningham PhD,

    1. Department of Family and Community Medicine, The University of Arizona, Tucson, Arizona, USA
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  • Gautam Sajeev MSc,

    1. Social, Epidemiological Research Department, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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  • Stephen J. Kish PhD

    1. Social, Epidemiological Research Department, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Departments of Psychiatry and Pharmacology, University of Toronto, Toronto, Ontario, Canada
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  • Potential conflict of interest: Dr. Callaghan: This research was supported by an indirect institutional grant from the Ontario Ministry of Health and Long-Term Care to the Centre for Addiction and Mental Health (CAMH; this grant provides salary support to research scientists at CAMH). Dr. Cunningham received support from the Canada-US Fulbright Program and the Mexico-US Fulbright-García Robles Program, as part of the Fulbright Canada-Mexico Joint Award in North American Studies. Dr. S. Kish receives related research funding from: US NIH NIDA R01 DA017301 and DA025096; an Honorarium for a seminar on methamphetamine toxicity, Centre for Addiction and Mental Health, Toronto, Canada; and an expert witness fee to provide an opinion on amphetamine toxicity. Mr. G. Sajeev reports receiving no research funding in the last 12 months or at any time in his professional career.

Abstract

Because methamphetamine exposure to experimental animals can damage brain dopamine neurones, we examined whether hospital patients diagnosed with methamphetamine-related disorders might have greater risk of subsequent admission with a Parkinson's disease diagnosis. This was a population-based cohort study using all statewide inpatient hospital discharge records from July 1, 1990, through June 30, 2000, in California, USA, in which subjects aged at least 50 years were followed for up to 10 years. Individuals with reported methamphetamine-related conditions (n = 1,863; ICD-9 codes 304.4, 305.7, 969.7, and E854.2) were matched on demographic variables and follow-up time with those with primary appendicitis conditions (n = 9,315). The appendicitis group had a Parkinson's disease incidence rate no different than the rate found among members of a large health maintenance organization in California. Cox regression procedures were used to estimate group differences in the rates of receiving a subsequent inpatient diagnosis of Parkinson's disease (ICD-9 332.0). The methamphetamine group showed increased risk of a subsequent admission with Parkinson's disease compared with that of the matched appendicitis group (adjusted hazard ratio = 2.65, 95% CI, 1.17–5.98, P= 0.019). Study limitations include a population limited to hospital admissions, an uncertainty regarding diagnostic validity of the ICD-9 code 332.0 (Parkinson's disease), and a small number of incident cases with suspected Parkinson's disease. We strongly emphasize the preliminary nature of the findings. Nevertheless, these data, requiring replication, provide some evidence that methamphetamine users might be at greater than normal risk for developing Parkinson's disease. © 2010 Movement Disorder Society

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