Objective: Characterize the population with parkinsonism and exposure to antipsychotics who underwent dopamine transporter single-photon emission computed tomography (DATSPECT).

Background: Atypical antipsychotics are used in  refractory depression and anxiety, which are highly prevalent in Parkinson’s disease (PD) and can present in the prodromal period. While less commonly associated with atypical antipsychotics than typical antipsychotics, drug induced parkinsonism (DIP) remains a concern and in susceptible individuals, these drugs may unmask subclinical PD^1,2.

Methods: We identified individuals with parkinsonism, exposure to antipsychotics, and DATSPECT imaging who were evaluated by a neurologist between March 2011 and February 2016. We abstracted information regarding demographics, psychiatric history, clinical characteristics of parkinsonism, and DATSPECT imaging. We used descriptive statistics to characterize the population and either the chi-square test or Student’s t test as appropriate to compare the abnormal and normal DATSPECT groups.

Results: We identified sixteen individuals; eleven with abnormal DATSPECTs, indicative of neurodegenerative parkinsonism, and five with normal DATSPECTs, consistent with DIP. The abnormal DATSPECT group was 45% male with a mean age of 57.7.  The normal DATSPECT group was 60% male with a mean age of 59.4.  All 16 individuals had been exposed to an atypical antipsychotic, with 15 of the 16 having been exposed to only atypical antipsychotics. The indication for antipsychotics was depression and/or anxiety in 73% of the abnormal and 60% of the normal DATSPECT group. Of the examined clinical characteristics of parkinsonism, the only statistically significant difference observed was that there was no progression of symptoms among 80% in the normal DATSPECT group versus 18% in the abnormal DATSPECT (p=0.017). Interestingly, equal proportions in each group presented with asymmetric parkinsonism.

Conclusions: While this study was limited by a small sample size, our findings suggest that there are minimal clinical differences between DIP and PD. The most common indication for atypical antipsychotic use was depression and/or anxiety.  It is possible that motor features of PD may be unmasked by atypical antipsychotic use in certain patients with early disease, manifesting only premotor symptoms. 

References:

1. Erro, R.; Bhatia, K.P.; Tinazzi, M. Parkinsonism Following Neuroleptic Exposure: A Double Hit Hypothesis? Mov. Disord. 2001, 30, 780–785.
2. Foubert-Samier, A.; Helmer, C.; Perez, F.; Le Goff, M.; Auriacombe, S.; Elbaz, A.; Dartigues, J.F.; Tison, F. Past exposure to neuroleptic drugs and risk of Parkinson disease in an elderly cohort. Neurology 2012, 79, 1615–1621.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-use-of-atypical-antipsychotics-in-depression-and-anxiety-may-unmask-parkinsons-disease-a-retrospective-chart-review/