Clinical features of drug-induced Parkinsonism

Alterations in type 2 dopamine receptors across neuropsychiatric conditions: A large-scale PET cohort

PURPOSE

Aberrant dopaminergic function is linked with motor, psychotic, and affective symptoms, but studies have typically compared a single patient group with healthy controls.

METHODS

Here, we investigated the variation in striatal (caudate nucleus, nucleus accumbens, and putamen) and thalamic type 2 dopamine receptor (D2R) availability using [11C]raclopride positron emission tomography (PET) data from a large sample of 437 humans including healthy controls, and subjects with Parkinson's disease (PD), antipsychotic-naïve schizophrenia, severe violent behavior, pathological gambling, depression, and overweight. We analyzed regional group differences in D2R availability. We also analyzed the interregional correlation in D2R availability within each group.

RESULTS

Subjects with PD showed the clearest decline in D2R availability. Overall, the groups showed high interregional correlation in D2R availability, while this pattern was weaker in violent offenders. Subjects with schizophrenia, pathological gambling, depression, or overweight did not show clear changes in either the regional receptor availability or the interregional correlation.

CONCLUSION

We conclude that the dopaminergic changes in neuropsychiatric conditions might not only affect the overall receptor availability but also how coupled regions are across people. The region-specific receptor availability more profoundly links to the motor symptoms, while the between-region coupling might be disrupted in violence.

Agony of akathisia: a case of sodium valproate-induced akathisia

Akathisia is a subjective feeling of restlessness that often results in a compulsion to move. Drug-related causes are the most common aetiologies. It can often be confused with restless legs syndrome (RLS). We describe a case of valproate-induced akathisia that improved with drug cessation. This case reports a rare but treatable adverse effect of sodium valproate and highlights the importance of differentiating akathisia from RLS.

Prevention of Parkinson's Disease: From Risk Factors to Early Interventions

Parkinson's disease (PD) is a debilitating neurological disorder characterized by progressively worsening motor dysfunction. Currently, available therapies merely alleviate symptoms, and there are no cures. Consequently, some researchers have now shifted their attention to identifying the modifiable risk factors of PD, with the intention of possibly implementing early interventions to prevent the development of PD. Four primary risk factors for PD are discussed including environmental factors (pesticides and heavy metals), lifestyle (physical activity and dietary intake), drug abuse, and individual comorbidities. Additionally, clinical biomarkers, neuroimaging, biochemical biomarkers, and genetic biomarkers could also help to detect prodromal PD. This review compiled available evidence that illustrates the relationship between modifiable risk factors, biomarkers, and PD. In summary, we raise the distinct possibility of preventing PD via early interventions of the modifiable risk factors and early diagnosis.

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

Background: Parkinsonism is a common side-effect of antipsychotic drugs especially in older adults, who also present with a higher frequency of neurodegenerative disorders like Idiopathic Parkinson’s disease (IPD). Distinguishing between antipsychotic-induced parkinsonism (AIP) and IPD is challenging due to clinical similarities. Up to 20% of older adults may suffer from persisting parkinsonism months after discontinuation of antipsychotics, suggesting underlying neurodegeneration. A review of the literature on AIP in older adults is presented, focusing on epidemiology, clinical aspects, and management. Methods: A literature search was undertaken on EMBASE, MEDLINE and PsycINFO, for articles on parkinsonism induced by antipsychotic drugs or other dopamine 2 receptor antagonists in subjects aged 65 or older. Results: AIP in older adults is the second most common cause of parkinsonism after IPD. Older age, female gender, exposure to high-potency first generation antipsychotics, and antipsychotic dosage are the main risk factors. The clinical presentation of AIP resembles that of IPD, but is more symmetrical, affects upper limbs more, and tends to have associated motor phenomena such as orofacial dyskinesias and akathisia. Presence of olfactory dysfunction in AIP suggests neurodegeneration. Imaging of striatal dopamine transporters is widely used in IPD diagnosis and could help to distinguish it from AIP. There is little evidence base for recommending pharmacological interventions for AIP, the best options being dose-reduction/withdrawal, or switching to a second-generation drug. Conclusions: AIP is a common occurrence in older adults and it is possible to differentiate it from IPD. Further research is needed into its pathophysiology and on its treatment.

Secondary parkinsonism due to drugs, vascular lesions, tumors, trauma, and other insults

In addition to neurodegenerative disorders, there are many secondary forms of parkinsonism. The most common cause for secondary parkinsonism is the intake of distinct drugs. Neuroleptics and calcium channel blockers have been mainly described to induce parkinsonism, but also other drugs were suspected to cause or worsen parkinsonism. Another common cause for secondary parkinsonism are vascular lesions (i.e. vascular parkinsonism). Furthermore, also brain tumors have been described as rare causes for parkinsonism. Moreover, parkinsonism can be caused by chronic traumatic encephalopathy, which is a special case, since secondary insults to the brain leads to the occurrence of a neuropathologically defined disease. Other rare causes for secondary parkinsonism are lesions caused by infectious or immunological diseases as well as toxins or street drugs.