Parkinsonism in the psychiatric setting: an update on clinical differentiation and management

Abstract

Parkinsonism is seen frequently in patients with psychiatric conditions. Drug-induced parkinsonism (DIP) is the second most common cause of parkinsonism in the general population after Parkinson’s disease (PD) but a range of rarer aetiologies, some of them reversible, should also be considered in patients of all ages. DIP is more common in older patients, as are neurodegenerative diseases that may produce parkinsonism and it is relatively more likely that drug exposure could be unmasking an underlying process in this population. There is an extensive literature on differentiating DIP from PD but clinical features can be indistinguishable and many proposed investigations are not readily available. Aside from cessation of the responsible medication, there is no clear consensus on treatment strategies or duration of treatment. Practically, a delicate balance must be achieved between ameliorating parkinsonism and avoiding recurrent psychosis. Long-term prognosis in the setting of DIP remains unclear. We review the features that may differentiate DIP from other causes of parkinsonism in patients with psychiatric illness, provide an update on relevant investigations and discuss management strategies. The use of atypical antipsychotics for a broad range of indications highlights the ongoing relevance of DIP.

Recognition and Management of Antipsychotic-Induced Parkinsonism in Older Adults: A Narrative Review

“…Older adults may also have an increased sensitivity to the anticholinergic effects of APs leading to constipation, blurred vision, dry mouth, and urinary retention [81]. Urinary symptoms (urgency, frequency, and nocturia), sleep disturbances (daytime sleepiness, restless legs), concentration problems, sexual dysfunction, and olfactory dysfunction, have all been significantly associated with IPD compared to DIP [4,6,69,80,82]. Olfactory impairment, in particular, is very prevalent in IPD [6,82] and represents an early sign of neurodegeneration; but it is not a common symptom of DIP [69], although this has been reported [83].…”

“…Urinary symptoms (urgency, frequency, and nocturia), sleep disturbances (daytime sleepiness, restless legs), concentration problems, sexual dysfunction, and olfactory dysfunction, have all been significantly associated with IPD compared to DIP [4,6,69,80,82]. Olfactory impairment, in particular, is very prevalent in IPD [6,82] and represents an early sign of neurodegeneration; but it is not a common symptom of DIP [69], although this has been reported [83]. It has been suggested that olfactory function tests may be a useful tool in the differential diagnosis between DIP and IPD [84], and also in the diagnosis of "masked" IPD in patients with DIP [6] who do not seem to recover after withdrawal of the offending drug.…”

“…However, SPECT using Iodine-123-Ioflupane (DaTscan) is the only imaging technique approved by the European Medicines Agency in 2000, and the US Food and Drug Administration in 2011 to differentiate essential tremor and diseases related to PD [86][87][88]. Since DIP is considered not to be related to nigrostriatal pathway degeneration, this modality of brain scanning has been used to distinguish cases of DIP (normal DaT striatal uptake of tracer) from IPD (reduced striatal uptake) [7,73,75,77,79,82,85,[87][88][89][90][91][92][93][94][95][96][97]. Even in the preliminary stages of IPD, DaT uptake in the striatum can be significantly decreased leading to an abnormal DaT scan [98].…”

“…Even in the preliminary stages of IPD, DaT uptake in the striatum can be significantly decreased leading to an abnormal DaT scan [98]. By contrast, DIP is considered a form of postsynaptic parkinsonism via D2R blockade and has negligible affinity for DaT, which leads to a normal DaT scan in pure DIP [82,88]. A meta-analysis reported that pooled accuracy measures to differentiate IPD from vascular parkinsonism and DIP were relatively high, with a sensitivity of 85% and a specificity of 80% [87].…”

“…Cardiac MIBG scintigraphy is not widely used or funded as a test for IPD in most countries, which may be the reason for the scarcity of studies using this diagnostic technique [82]. Nevertheless, it has been proposed to help diagnose IPD by means of looking at cardiac postganglionic autonomic involvement [99].…”