title: Methamphetamine/amphetamine abuse and risk of Parkinson's disease in Utah: a population-based assessment.
abstract: BACKGROUND
  Despite widespread use of methamphetamine and other amphetamine-type stimulants (METH/AMPH), little is known about the long-term medical consequences of METH/AMPH abuse and dependence. Preclinical neurotoxicity findings raise public health concerns that these stimulants may damage dopamine neurons, resulting in dopamine-related disorders such as Parkinson's disease (PD).
  
  
  METHODS
  A retrospective design was used to examine statewide medical records (1996 through 2011) linked to the Utah Population Database. Individuals 30 years or older on December 31, 2011 were assigned to a METH/AMPH cohort (ICD-9-CM 304.4, 305.7, 969.7, E854.2; N=4935), a cocaine cohort (ICD-9-CM 304.2, 305.6, 968.5, E855.2; N=1867) or a population cohort unexposed to drugs or alcohol for control selection. A competing-risks, proportional hazards model was used to determine whether the METH/AMPH or cocaine cohorts were at increased risk of developing PD (ICD-9-CM 332.0) or PD/parkinsonism/essential tremor (PD/PT; ICD-9-CM 332.0, 332.1, 333.0, 333.1) compared to individually sex- and age-matched controls (5:1 control to case ratio; N=34,010).
  
  
  RESULTS
  In METH/AMPH users, we observed an increased risk of PD and PD/PT (HRPD=2.8, 95%CI 1.6-4.8, P<10(-3); HRPD/PT=3.1, 95%CI 1.9-4.9, P<10(-4)) compared to population-based controls. Conversely, cocaine users exhibited no elevated risk of PD compared to controls.
  
  
  CONCLUSIONS
  We observed a near three-fold increased risk of PD in METH/AMPH users vs. controls which confirms prior observations and supports that PD risk in users may be higher than previous estimates. A suggestion that female and male users may differ in PD susceptibility warrants further study.
authors.affiliation: Department of Internal Medicine, University of Utah, Salt Lake City, UT 84112, United States; Population Sciences, Huntsman Cancer Institute, Salt Lake City, UT 84112, United States. Electronic address: karen.curtin@hsc.utah.edu.
authors.forename: Karen
authors.initials: K
authors.lastname: Curtin
authors.affiliation: Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, United States; School of Dentistry, University of Utah, Salt Lake City, UT 84112, United States.
authors.forename: Annette E
authors.initials: AE
authors.lastname: Fleckenstein
authors.affiliation: Intermountain Healthcare, Salt Lake City, UT 84111, United States; Utah Foundation for Biomedical Research, Provo, UT 84601, United States.
authors.forename: Reid J
authors.initials: RJ
authors.lastname: Robison
authors.affiliation: Intermountain Healthcare, Salt Lake City, UT 84111, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Crookston
authors.affiliation: Population Sciences, Huntsman Cancer Institute, Salt Lake City, UT 84112, United States; Department of Family and Consumer Studies, University of Utah, Salt Lake City, UT 84112, United States.
authors.forename: Ken R
authors.initials: KR
authors.lastname: Smith
authors.affiliation: Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, United States; School of Dentistry, University of Utah, Salt Lake City, UT 84112, United States.
authors.forename: Glen R
authors.initials: GR
authors.lastname: Hanson
mesh_terms: D000328:Adult; D000368:Aged; D019969:Amphetamine-Related Disorders / Q000453:epidemiology*; D019970:Cocaine-Related Disorders / Q000453:epidemiology*; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D014589:Utah / Q000453:epidemiology
keywords: Amphetamine; Cocaine; Dopamine; Drug abuse; Methamphetamine; Parkinson's disease