Tardive parkinsonism in a bipolar patient: post-mortem examination supports a physiological rather than pathological dysfunction

Chronic Neuroleptic-Induced Parkinsonism Examined With Positron Emission Tomography

BACKGROUND

Neuroleptic drug-induced parkinsonism (NIP) is a leading cause of parkinsonism, particularly in aging. Based on abnormal dopamine transporter scan results, individuals displaying chronic NIP are often diagnosed with Lewy-body Parkinson's disease (PD), but this assumption needs further substantiation.

OBJECTIVE

To quantitate the profile of striatal dopaminergic nerve terminal density in NIP relative to PD.

METHODS

We used the positron emission tomography ligand [¹¹ C](+)-dihydrotetrabenazine targeting vesicular monoamine transporter type 2 (VMAT2) binding sites and collected various clinical parameters (motor ratings, olfaction, polysomnography to document rapid eye movement sleep muscle activity, quantitative sensory testing for pain thresholds) possibly predicting binding results in patients older than age 50 living with schizophrenia spectrum disorders under long-term stable antipsychotic drug treatment, with (N = 11) or without (N = 11) chart documention of chronic NIP, and compared them to healthy volunteers (N = 11) and others medicated for PD (N = 12).

RESULTS

Striatal VMAT2 binding was dichotomous in the NIP group between those with spared (N = 5) or low (N = 6) PD-like values. Striatal binding reduction in the low VMAT2-NIP group was asymmetric without the gradient of maximal involvement in the posterior putamen typical of PD. Anosmia was the only nonmotor parameter measured matching the abnormal striatal VMAT2 binding status.

CONCLUSION

These preliminary observations suggest that striatal VMAT2 binding is abnormal in a fraction of chronic NIP cases and differs in spatial distribution from PD. The possibility of a drug-induced axonopathy and resultant synaptopathy, as well as the evolution of the binding deficit, warrant further longitudinal studies in a large cohort. © 2020 International Parkinson and Movement Disorder Society.

Risk for antipsychotic-induced extrapyramidal symptoms: influence of family history and genetic susceptibility

OBJECTIVES

This study aims to further evaluate the impact of family history of primary movement disorders (FHpMD) and a candidate genetic variant on risk of antipsychotic-induced extrapyramidal symptoms (EPS).

METHODS

We examined 156 (76 men) inpatients receiving antipsychotics for EPS and FHpMD stratified by patient characteristics. The genetic analysis included genotyping of a multiallelic dinucleotide polymorphism in the ATP1A3 gene.

RESULTS

EPS lifetime prevalence was 69% and more frequent in the presence of FHpMD (p = 0.052), particularly in patients younger than 60 years (p = 0.012) and with acute dystonic reactions. The ATP1A3 polymorphism showed an allele length-dependent association with parkinsonism (p=0.019 uncorrected, p=0.057 corrected) exclusively. Carriers of the shortest allele had a 7.7-fold increased risk for parkinsonism.

CONCLUSIONS

The association of FHpMD and EPS may be linked to the EPS subtype and age of the patient. A common ATP1A3 genomic variation may represent a susceptibility factor for the risk for antipsychotic-induced parkinsonism in an allele-dependent manner.