Background: Methamphetamine use has been posited to be a risk factor for the development of Parkinson’s disease (PD) and parkinsonism. The clinical implications of a potential association between methamphetamine use and PD are considered. Methods: A review of methamphetamine and PD and parkinsonism was conducted, including evidence from animal models, clinical and population studies. Results: There is biological plausibility to a link between methamphetamine use and PD. Though clinical and epidemiological evidence in this area is scant, a number of studies suggest that methamphetamine is associated with a moderately increased risk of PD and parkinsonism, and may also lead to premature onset of PD. The long lag time between exposure to methamphetamine and onset of PD, the potential for recovery from neurotoxic effects, and tobacco smoking each may attenuate the association. Individual and drug use characteristics that may modulate a user’s risk remain poorly understood. Conclusions: The use of methamphetamine may be an initiating event in the development of PD and parkinsonism, in addition to other risk factors that a given individual may hold. Clinicians should be vigilant to signs of prodromal and emerging PD among methamphetamine users. In individuals with premature onset illness, information on current or prior exposure to methamphetamine should be sought.

Introduction

Methamphetamine use is a significant public health problem, with an estimated 35 million stimulant users worldwide, predominantly of methamphetamine (Degenhardt and Hall, 2012; Degenhardt et al., 2013; UNODC, 2016). Harmful physical and mental health consequences are common, including cardiovascular and cerebrovascular pathology, psychosis, suicide and premature mortality (Callaghan et al., 2012a; Darke et al., 2008, 2011; Karch, 2015). The stimulants methamphetamine and its active metabolite amphetamine are highly related and are hereafter referred to as methamphetamine (McKetin et al., 2016) There has been recent speculation that methamphetamine use may be associated with greater risk of developing Parkinson’s disease (PD). Here, we examine the question whether methamphetamine users are at increased risk of PD or parkinsonism. There is an extensive pre-clinical literature investigating the effects of methamphetamine on brain tissue, and specifically its propensity to cause brain dopamine neuronal damage such as that observed in Parkinson’s disease. This literature has been comprehensively reviewed elsewhere (Kish et al., 2017). The current review extends beyond these preclinical findings by reviewing evidence from clinical and population studies of PD and parkinsonism among individuals exposed to methamphetamine. The clinical implications for methamphetamine users, their communities and clinicians are considered.