Journal of Psychiatric Research 60 (2015) 187
Contents lists available at ScienceDirect
Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/psychires
Letter to the Editor
Zolpidem use as a predictor of Parkinson's disease Contributors
Sir, In a retrospective observational study using data from the Taiwan National Health Insurance Research Database, Yang et al. (2014) showed that the use of zolpidem for >3 months was associated with a 30e40% increased risk of incident Parkinson's disease across a 5-year follow up period. On the surface, it appears that Yang et al. (2014) controlled for confounding by indication because the experimental and control groups were both selected on the basis of presence of sleep disturbance. However, importantly, Yang et al. (2014) neither specified nor controlled for the nature and severity of the sleep disturbance and the persistence thereof. Furthermore, they did not present a sensitivity analysis for PD risk associated with the use of other hypnotic drugs. Therefore, the most parsimonious explanation for their findings is that patients with persistent sleep disturbance, operationalized as those who need zolpidem for >3 months, are more likely to develop PD later. Persistent sleep disturbance and prolonged zolpidem use, therefore, are merely predictors and not causal for PD. In this context, it has long been known that PD is associated with sleep disorders that may antedate the onset of motor symptoms by many years (Raggi et al., 2013). Yang et al. (2014) failed to consider this point of view and, instead, posited a causal role for zolpidem with an unknown mechanism.
I am the sole contributor to this letter. Conflict of interest I have no conflicting interests with regard to the present submission. Acknowledgements I have no acknowledgements to declare.
References Raggi A, Bella R, Pennisi G, Neri W, Ferri R. Sleep disorders in Parkinson's disease: a narrative review of the literature. Rev Neurosci 2013;24:279e91. Yang YW, Hsieh TF, Yu CH, Huang YS, Lee CC, Tsai TH. Zolpidem and the risk of Parkinson's disease: a nationwide population-based study. J Psychiatr Res 2014 Jul 25. http://dx.doi.org/10.1016/j.jpsychires.2014.07.003. pii: S0022e3956(14) 00200-3. [Epub ahead of print].
Chittaranjan Andrade* Department of Psychopharmacology, National Institute of Mental Health and Neurosciences, Bangalore 560 029, India *
Role of funding source This submission was unfunded.
http://dx.doi.org/10.1016/j.jpsychires.2014.09.015 0022-3956/© 2014 Elsevier Ltd. All rights reserved.
Tel.: þ91 80 26995109; fax: þ91 80 26564830. E-mail addresses: [email protected], [email protected]. 5 September 2014
Contents lists available at ScienceDirect
Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/psychires
Letter to the Editor
Zolpidem use as a predictor of Parkinson's disease Contributors
Sir, In a retrospective observational study using data from the Taiwan National Health Insurance Research Database, Yang et al. (2014) showed that the use of zolpidem for >3 months was associated with a 30e40% increased risk of incident Parkinson's disease across a 5-year follow up period. On the surface, it appears that Yang et al. (2014) controlled for confounding by indication because the experimental and control groups were both selected on the basis of presence of sleep disturbance. However, importantly, Yang et al. (2014) neither specified nor controlled for the nature and severity of the sleep disturbance and the persistence thereof. Furthermore, they did not present a sensitivity analysis for PD risk associated with the use of other hypnotic drugs. Therefore, the most parsimonious explanation for their findings is that patients with persistent sleep disturbance, operationalized as those who need zolpidem for >3 months, are more likely to develop PD later. Persistent sleep disturbance and prolonged zolpidem use, therefore, are merely predictors and not causal for PD. In this context, it has long been known that PD is associated with sleep disorders that may antedate the onset of motor symptoms by many years (Raggi et al., 2013). Yang et al. (2014) failed to consider this point of view and, instead, posited a causal role for zolpidem with an unknown mechanism.
I am the sole contributor to this letter. Conflict of interest I have no conflicting interests with regard to the present submission. Acknowledgements I have no acknowledgements to declare.
References Raggi A, Bella R, Pennisi G, Neri W, Ferri R. Sleep disorders in Parkinson's disease: a narrative review of the literature. Rev Neurosci 2013;24:279e91. Yang YW, Hsieh TF, Yu CH, Huang YS, Lee CC, Tsai TH. Zolpidem and the risk of Parkinson's disease: a nationwide population-based study. J Psychiatr Res 2014 Jul 25. http://dx.doi.org/10.1016/j.jpsychires.2014.07.003. pii: S0022e3956(14) 00200-3. [Epub ahead of print].
Chittaranjan Andrade* Department of Psychopharmacology, National Institute of Mental Health and Neurosciences, Bangalore 560 029, India *
Role of funding source This submission was unfunded.
http://dx.doi.org/10.1016/j.jpsychires.2014.09.015 0022-3956/© 2014 Elsevier Ltd. All rights reserved.
Tel.: þ91 80 26995109; fax: þ91 80 26564830. E-mail addresses: [email protected], [email protected]. 5 September 2014
