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. 2021 Jun;36(6):1353-1361.
doi: 10.1002/mds.28484. Epub 2021 Jan 6.

Increased Risk of Parkinson's Disease in Patients With Schizophrenia Spectrum Disorders

Tomi Kuusimäki  1 , Haidar Al-Abdulrasul  1   2 , Samu Kurki  3 , Jarmo Hietala  4 , Sirpa Hartikainen  5   6 , Marjaana Koponen  5   6   7 , Anna-Maija Tolppanen  5 , Valtteri Kaasinen  1
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Free article

Increased Risk of Parkinson's Disease in Patients With Schizophrenia Spectrum Disorders

Tomi Kuusimäki et al. Mov Disord. 2021 Jun.
Free article

Abstract

Background: PD comorbid with schizophrenia has been considered rare because these diseases associate with opposite alterations in the brain dopamine system. The objective of this study was to investigate the risk of PD after a diagnosis of a schizophrenia spectrum disorder.

Methods: Regionally, this was a retrospective record-based case-control study. The cohort included 3045 PD patients treated 2004-2019 in southwestern Finland. Nationally this was a nested case-control study using registers to examine Finnish patients who received a clinically confirmed PD diagnosis 1996-2015 (n = 22,189). PD patients with previously diagnosed schizophrenia spectrum disorder (separate analysis for schizophrenia) were included. Comparable non-PD control groups were derived from both data sets. All PD diagnoses were based on individual clinical examinations by certified neurologists.

Results: In PD patients, the prevalence of earlier schizophrenia spectrum disorder was 0.76% in regional data and 1.50% in nationwide data. In age-matched controls, the prevalence in the regional and national data was 0.16% and 1.31%, respectively. The odds ratio for PD after schizophrenia spectrum disorder diagnosis was 4.63 (95% CI, 1.76-12.19; P < 0.01) in the regional data and 1.17 (95% CI, 1.04-1.31; P < 0.01) in the national data.

Conclusions: Schizophrenia spectrum disorder increases the risk of PD later in life. This association was observed in both individual patient data and nationwide register data. Therefore, despite the opposite dopaminergic disease mechanisms, schizophrenia spectrum disorder increases rather than decreases the risk of PD. The increased PD risk could be related to risk-altering effects of dopamine receptor antagonists or to the increased vulnerability of the dopamine system induced by illness phase-dependent dopamine dysregulation in schizophrenia/schizophrenia spectrum disorder. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Keywords: Parkinson's disease; comorbidity; dopamine; schizophrenia.

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References

    1. Kalia LV, Lang AE. Parkinson's disease. Lancet 2015;386(9996):896-912.
    1. Gallagher CL, Oakes TR, Johnson SC, et al. Rate of 6-[18F]fluorodopa uptake decline in striatal subregions in Parkinson's disease. Mov Disord 2011;26(4):614-620.
    1. Grace AA. Phasic versus tonic dopamine release and the modulation of dopamine system responsivity: a hypothesis for the etiology of schizophrenia. Neuroscience 1991;41(1):1-24.
    1. Grace AA. Dysregulation of the dopamine system in the pathophysiology of schizophrenia and depression. Nat Rev Neurosci 2016;17(8):524-532.
    1. Howes OD, Kapur S. The dopamine hypothesis of schizophrenia: version III-the final common pathway. Schizophr Bull 2009;35(3):549-562.

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