A severe and irreversible case of tardive rigid-akinetic parkinsonian syndrome: the role of the DaTscan

Differences in cause and 12-month follow-up outcome of parkinsonian symptoms in depressed older adults treated with antipsychotics: a case series

BACKGROUND

Parkinsonian symptoms are common adverse effects of antipsychotics. Older adults are particularly vulnerable to drug-induced parkinsonism. Nonetheless, parkinsonian symptoms in seniors treated with antipsychotics cannot be straightforwardly attributed to antipsychotic medication. A comprehensive diagnostic workup is necessary in many cases in order to shed light on the cause of such symptoms in this patient population.

CASE SERIES

Eight cases of hospitalized depressed older adults with parkinsonian symptoms, who were treated for at least one year with antipsychotics, are reported. Based on neurological consultation, structural brain imaging and Ioflupane (I-123) dopamine transporter (DAT) single photon emission computerized tomography (SPECT), Parkinson's disease was diagnosed in one case, idiopathic tremor in another, vascular parkinsonism in another one, while in another individual parkinsonian symptoms persisted at 12-month post-discharge follow-up even though his/her symptoms were classified as drug-induced on discharge. In four patients, parkinsonian symptoms were definitely drug-induced and no movement disturbances were reported at follow-up.

CONCLUSIONS

Differences in the cause and outcome of parkinsonian symptoms in seniors treated with antipsychotics merit systematic and in-depth study considering the therapeutic and prognostic implications of an accurate detection of the cause of such symptoms. Familiarizing clinical psychiatrists with these differences could pave the way towards approaching seniors with severe, atypical and/or persistent parkinsonian symptoms in a more individualized diagnostic and therapeutic manner, and towards more cautious prescribing of antipsychotics in this age group.

Linking F-box protein 7 and parkin to neuronal degeneration in Parkinson's disease (PD)

Mutations of F-box protein 7 (FBXO7) and Parkin, two proteins in ubiquitin-proteasome system (UPS), are both implicated in pathogenesis of dopamine (DA) neuron degeneration in Parkinson's disease (PD). Parkin is a HECT/RING hybrid ligase that physically receives ubiquitin on its catalytic centre and passes ubiquitin onto its substrates, whereas FBXO7 is an adaptor protein in Skp-Cullin-F-box (SCF) SCF(FBXO7) ubiquitin E3 ligase complex to recognize substrates and mediate substrates ubiquitination by SCF(FBXO7) E3 ligase. Here, we discuss the overlapping pathophysiologic mechanisms and clinical features linking Parkin and FBXO7 with autosomal recessive PD. Both proteins play an important role in neuroprotective mitophagy to clear away impaired mitochondria. Parkin can be recruited to impaired mitochondria whereas cellular stress can promote FBXO7 mitochondrial translocation. PD-linked FBXO7 can recruit Parkin into damaged mitochondria and facilitate its aggregation. WT FBXO7, but not PD-linked FBXO7 mutants can rescue DA neuron degeneration in Parkin null Drosophila. A better understanding of the common pathophysiologic mechanisms of these two proteins could unravel specific pathways for targeted therapy in PD.