Drug-induced parkinsonism

Prevalence and causative drugs of drug-induced Parkinsonism in pediatric patients

Although several studies provided evidence on the epidemiology of drug-induced Parkinsonism (DIP) and its causative drugs, it is still limited in pediatrics. This study aimed to investigate the prevalence and risk of DIP in pediatrics. We used the Health Insurance Review and Assessment Service-Pediatric Patients Sample in Korea between 2010 and 2017 to estimate the annual prevalence of DIP and causative drug use using a cross-sectional design. The risk of DIP associated with causative drugs was evaluated using a case-crossover design. Adjusted odds ratios (aOR) with 95% confidence intervals (CI) were calculated using a conditional logistic regression. A total of 2925 pediatric patients had diagnosed with DIP from 2010 to 2017. Most patients were aged between 12 and19 years old, and 99.8% had any diagnosis of mental health disorder (MHD). During the study period, the prevalence of DIP increased by 10.0-fold from 2010 to 2017. All causative drugs showed a corresponding increase in their use, with atypical antipsychotics being the most prominent (increase ratio, 2.07). For both in the prevalence of DIP and atypical antipsychotic use, the increment was much bigger in patients with non-psychotic MHD than that in patients with psychotic MHD. In the case-crossover study, antipsychotics showed the largest aOR with DIP. Risperidone among antipsychotics showed the highest risk for DIP (aOR = 7.09, 95% CI = 3.83-13.09), followed by aripiprazole (aOR = 5.03, 95% CI = 2.88-8.80). This study suggests that the increase in DIP prevalence in pediatric patients might be because of the increased use of atypical antipsychotics.

Treatment Changes and Prognoses in Patients with Incident Drug-Induced Parkinsonism Using a Korean Nationwide Healthcare Claims Database

This retrospective cohort study assessed treatment changes and prognoses after incident drug-induced parkinsonism (DIP). We used the National Health Insurance Service's National Sample Cohort database in South Korea. We selected patients diagnosed with incident DIP and given prescriptions to take offending drugs (antipsychotics, gastrointestinal (GI) motility drugs, or flunarizine) for a period of time that overlapped with the time of DIP diagnosis during 2004-2013. The proportion of patients experiencing each type of treatment change and prognosis was assessed for 2 years after DIP diagnosis. We identified 272 patients with incident DIP (51.9% of patients were aged ≥ 60 years and 62.5% of them were women). Switching (38.4%) and reinitiation (28.8%) were the most common modifications in GI motility drug users, whereas dose adjustment (39.8%) and switching (23.0%) were common in antipsychotic users. The proportion of persistent users was higher among antipsychotic users (7.1%) than that among GI motility drug users (2.1%). Regarding prognosis, 26.9% of patients experienced DIP recurrence or persistence, the rate being the highest in persistent users and the lowest in patients who discontinued the drug. Among patients with incident DIP diagnoses, the patterns of treatment change and prognosis differed across the types of offending drugs. Over 25% of patients experienced DIP recurrence or persistence, highlighting the need for an effective strategy to prevent DIP.

Permanent non-progressive cinnarizine and flunarizine-induced parkinsonism: An under-recognized tardive syndrome in the elderly?

Secondary parkinsonism induced by exposure to dopamine (DA) receptor antagonists as first and second generation antipsychotics, DA storage depleters, calcium channel blockers, benzamides substituted and other classes of drugs is traditionally believed to be completely reversible in most of patients following withdrawal of the offending drug even though after a variable time delay. The lack of recovery or initial full recovery with subsequent development of progressive parkinsonism has been regarded to result from an underlying subclinical degenerative process like PD unmasked by the inducing drug. These well-recognized clinical outcomes of drug-induced parkinsonism (DIP) have disregarded the existence of another outcome, characterized by permanent non-progressive parkinsonism. This syndrome may fullfil the criteria of tardive parkinsonism, a controversial entity currently referred to as a persistent condition without indication of its long-term course and clinical features. On reviewing the published literature on DIP, we have identified two prospective long-term follow-up of elderly patients in which parkinsonism induced by the calcium channel antagonists cinnarizine and flunarizine became permanent and non-progressive following drug discontinuation in a non-negligible proportion of patients, consistent with the clinical concept of a true tardive syndrome, according to currently accepted criteria. The authors hypothesize that the development of tardive parkinsonism might be due to a neurotoxic effect of the pharmacodynamic proprieties of the calcium channel blockers and their metabolites, exerted on post-synaptic striatal neurons and/or a neurotoxic damage on presynaptic DA neurons in patients without an underlying subclinical degenerative parkinsonism, so accounting for the stable and non-progressive course over time.

Updated Perspectives on the Management of Drug-Induced Parkinsonism (DIP): Insights from the Clinic

Parkinsonism refers to the clinical combination of bradykinesia, rigidity, tremor, and postural instability. Parkinsonism is often neurodegenerative, but it can be secondary or iatrogenic, as in drug-induced parkinsonism (DIP), which is the topic of this review. We review the pathophysiology of DIP, differentiate DIP and idiopathic Parkinson's disease (PD), list culprit medications in the development of DIP, discuss the diagnosis of DIP as well as the motor and nonmotor signs and symptoms that can help with differentiation of DIP and PD, and detail the management of DIP.

Pathophysiological Mechanisms of Antipsychotic-Induced Parkinsonism

Among neurological adverse reactions in patients with schizophrenia treated with antipsychotics (APs), drug-induced parkinsonism (DIP) is the most common motility disorder caused by drugs affecting dopamine receptors. One of the causes of DIP is the disruption of neurotransmitter interactions that regulate the signaling pathways of the dopaminergic, cholinergic, GABAergic, adenosinergic, endocannabinoid, and other neurotransmitter systems. Presently, the development mechanisms remain poorly understood despite the presence of the considered theories of DIP pathogenesis.

Use of antipsychotics and long-term risk of parkinsonism

INTRODUCTION

Few epidemiological studies have assessed the risk of parkinsonisms after prolonged use of neuroleptics. We aimed to examine the long-term risk of degenerative parkinsonisms (DP) associated with previous use of neuroleptics.

METHODS

All residents in Piedmont, Northern-west Italy, older than 39 years (2,526,319 subjects), were retrospectively followed up from 2013 to 2017. Exposure to neuroleptics was assessed through the regional archive of drug prescriptions. The development of DP was assessed using the regional archives of both drug prescriptions and hospital admissions. We excluded prevalent DP cases at baseline as well as those occurred in the first 18 months (short-term risk). The risk of DP associated with previous use of neuroleptics was examined through Cox regression, using a matched cohort design.

RESULTS

The risk of DP was compared between 63,356 exposed and 316,779 unexposed subjects. A more than threefold higher risk of DP was observed among subjects exposed to antipsychotics, compared to those unexposed (HR = 3.27, 95% CI 3.00-3.57), and was higher for exposure to atypical than typical antipsychotics. The risk decreased after 2 years from therapy cessation but remained significantly elevated (HR = 2.38, 95% CI 1.76-3.21).

CONCLUSIONS

These results indicate a high risk of developing DP long time from the start of use and from the cessation for both typical and atypical neuroleptics, suggesting the need of monitoring treated patients even after long-term use and cessation.

Candidate Genes Encoding Dopamine Receptors as Predictors of the Risk of Antipsychotic-Induced Parkinsonism and Tardive Dyskinesia in Schizophrenic Patients

(1) Introduction: Extrapyramidal disorders form the so-called extrapyramidal syndrome (EPS), which is characterized by the occurrence of motor disorders as a result of damage to the basal ganglia and the subcortical-thalamic connections. Often, this syndrome develops while taking medications, in particular antipsychotics (APs). (2) Purpose: To review studies of candidate genes encoding dopamine receptors as genetic predictors of development of AP-induced parkinsonism (AIP) and AP-induced tardive dyskinesia (AITD) in patients with schizophrenia. (3) Materials and Methods: A search was carried out for publications of PubMed, Web of Science, Springer, and e-Library databases by keywords and their combinations over the last 10 years. In addition, the review includes earlier publications of historical interest. Despite extensive searches of these commonly used databases and search terms, it cannot be ruled out that some publications were possibly missed. (4) Results: The review considers candidate genes encoding dopamine receptors involved in pharmacodynamics, including genes DRD1, DRD2, DRD3, and DRD4. We analyzed 18 genome-wide studies examining 37 genetic variations, including single nucleotide variants (SNVs)/polymorphisms of four candidate genes involved in the development of AIP and AITD in patients with schizophrenia. Among such a set of obtained results, only 14 positive associations were revealed: rs1799732 (141CIns/Del), rs1800497 (C/T), rs6275 (C/T), rs6275 (C/T) DRD2; rs167771 (G/A) DRD3 with AIP and rs4532 (A/G) DRD1, rs6277 (C/T), rs6275 (C/T), rs1800497 (C/T), rs1079597 (A/G), rs1799732 (141CIns/Del), rs1045280 (C/G) DRD2, rs6280 (C/T), rs905568 (C/G) DRD3 with AITD. However, at present, it should be recognized that there is no final or unique decision on the leading role of any particular SNVs/polymorphisms in the development of AIP and AITD. (5) Conclusion: Disclosure of genetic predictors of the development of AIP and AITD, as the most common neurological adverse drug reactions (ADRs) in the treatment of patients with psychiatric disorders, may provide a key to the development of a strategy for personalized prevention and treatment of the considered complication of AP therapy for schizophrenia in real clinical practice.

Cell-Type-Specific High Throughput Toxicity Testing in Human Midbrain Organoids

Toxicity testing is a crucial step in the development and approval of chemical compounds for human contact and consumption. However, existing model systems often fall short in their prediction of human toxicity in vivo because they may not sufficiently recapitulate human physiology. The complexity of three-dimensional (3D) human organ-like cell culture systems ("organoids") can generate potentially more relevant models of human physiology and disease, including toxicity predictions. However, so far, the inherent biological heterogeneity and cumbersome generation and analysis of organoids has rendered efficient, unbiased, high throughput evaluation of toxic effects in these systems challenging. Recent advances in both standardization and quantitative fluorescent imaging enabled us to dissect the toxicities of compound exposure to separate cellular subpopulations within human organoids at the single-cell level in a framework that is compatible with high throughput approaches. Screening a library of 84 compounds in standardized human automated midbrain organoids (AMOs) generated from two independent cell lines correctly recognized known nigrostriatal toxicants. This approach further identified the flame retardant 3,3',5,5'-tetrabromobisphenol A (TBBPA) as a selective toxicant for dopaminergic neurons in the context of human midbrain-like tissues for the first time. Results were verified with high reproducibility in more detailed dose-response experiments. Further, we demonstrate higher sensitivity in 3D AMOs than in 2D cultures to the known neurotoxic effects of the pesticide lindane. Overall, the automated nature of our workflow is freely scalable and demonstrates the feasibility of quantitatively assessing cell-type-specific toxicity in human organoids in vitro.

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.

Trimetazidine-Induced Parkinsonism: A Systematic Review

Importance: Trimetazidine (TMZ) is a medication given to patients with stable coronary artery disease. While it is reportedly well-tolerated, there are increasing numbers of reports of adverse events such as parkinsonism.

Objectives: The purpose of this study was to systematically review the currently available literature on TMZ-induced parkinsonism.

Evidence Review: A search of Scopus, MEDLINE, EMBASE, the Cochrane Library, the Health Technology Assessment Database, PubMed, Science Direct, and Google Scholar was conducted on or before November 7, 2019. The literature search included cohort studies, prospective and/or retrospective studies, meta-analysis, and other systematic reviews published as an original article, including abstracts and full texts. We included patients taking TMZ who developed one or more of the parkinsonian symptoms of bradykinesia, tremors, rigidity, and postural instability, where these symptoms improved after withdrawal of the said medication.

Findings: There are currently five studies on TMZ use and associated parkinsonism. The literature included two case reports, one case series, and one retrospective and one prospective study. We found no results from randomized clinical trials. Overall, 88 patients developed TMZ-induced parkinsonism. Regression of parkinsonism was reported in all of the participants after withdrawal of TMZ. A total of 49 patients (55.7%) had complete regression of symptoms, while 39 patients (44.3%) had significant reduction of symptoms. The duration between TMZ (dose, 60–80 mg/day) intake and onset of symptoms ranged from 4 months to 20 years. The most commonly reported extrapyramidal symptoms were akinesia, rigidity, postural disturbances, and gait disorders, which were usually mild and symmetric.

Conclusions and Relevance: The current literature suggests that TMZ can induce parkinsonism that is reversible with drug withdrawal. It is warranted to examine patients, especially the elderly, on TMZ for parkinsonian symptoms and those with pre-existing neurodegenerative diseases. Further studies are needed to assess the risk-benefit ratio of this drug, especially in the elderly age group.

Drug-Induced Parkinsonism Manifesting as Gait Freezing in a Patient With Traumatic Brain Injury: A Case Report

BACKGROUND

Among the neuropsychiatric complications commonly induced by traumatic brain injury (TBI), behavioral disorders, such as agitation and aggression, can hinder neurological recovery and deteriorate rehabilitation outcomes. Pharmacological treatment for behavioral disorders might be beneficial but could lead to drug-induced parkinsonism. We report a case of a patient with drug-induced parkinsonism manifested as freezing of gait after TBI, which improved with the cessation of the offending drugs and comprehensive rehabilitation.

CASE PRESENTATION

A 35-year-old male patient left with a TBI after a car accident was referred to our hospital. He had been on many neuropsychiatric medications, including atypical antipsychotics, for his agitated behaviors. He could walk independently but showed freezing of gait at the initiation of his gait, when turning to the side, when reaching his destination, and passing through narrow corridors. Under the impression of drug-induced parkinsonism, we gradually tapered the patient off his neuropsychiatric medications. He also underwent comprehensive rehabilitation, including gait training under visual and auditory cues and balance training. Five weeks after admission to the hospital, the patient's freezing of gait improved, with disappearance of his hesitation at gait initiation and a decreased freezing duration while turning around.

CONCLUSIONS

This is a rare report of drug-induced parkinsonism manifested as freezing of gait, which showed improvement after discontinuation of the causative drugs and subsequent rehabilitation.

Pediatric Iatrogenic Movement Disorders

The acute development of a movement disorder is often a dramatic and frightening experience for patients and families, often requiring urgent or emergent evaluation by a neurologist. In the assessment of these patients, one relies on the history, physical and neurologic examination to determine the etiology of the condition. We aim to demonstrate that a thorough medication history is an incredibly critical part of this evaluation as iatrogenic movement disorders can arise from exposure not only to psychoactive medications, but from drugs prescribed for a variety of nonneurologic disorders. This comprehensive review is organized by movement disorder semiology so that the reader can more readily develop a differential diagnosis when evaluating a patient with a movement disorder.

Common toxidromes in movement disorder neurology

BACKGROUND

Physicians can come across patients who are exposed to certain prescription drugs or toxins that can result in adverse effects and complications which have high rates of morbidity and mortality.

OBJECTIVE

To summarise the key clinical features and management of the common movement disorder toxidromes relevant to physicians (with an interest in neurology).

METHODS

We searched PUBMED from 1946 to 2016 for papers relating to movement toxidromes and their treatment. The findings from those studies were then summarised and are presented here.

RESULTS

The key features of 6 of the common movement disorder toxidromes and their treatment are tabulated and highlighted. The management of toxidromes with the highest mortality like neuroleptic malignant syndrome and serotonin syndrome are discussed in detail.

CONCLUSION

There are several toxidromes that have the potential to become a serious life-threatening emergency if there is a delay in recognition of key clinical features and instituting the appropriate treatment at the earliest is crucial.

A 5-Year Follow-up Study on the Relationship between Obstructive Sleep Apnea and Parkinson Disease

STUDY OBJECTIVE

Sleep disturbances are among the most common nonmotor symptoms of Parkinson disease. However, no large epidemiological data regarding the association between obstructive sleep apnea (OSA) and Parkinson disease have been reported. The goal of this study was to investigate the risk for Parkinson disease during a 5-y follow-up period after a diagnosis of OSA using a population-based dataset.

METHODS

The data for this retrospective longitudinal cohort study were retrieved from the Taiwan Longitudinal Health Insurance Database 2000. We identified 1,532 patients with OSA as the study cohort and randomly selected 7,660 patients as the comparison cohort. Each subject was individually followed up for a 5-y period to identify those in whom Parkinson disease subsequently developed. Stratified Cox proportional hazard regressions were performed as a means of comparing the 5-y risk of subsequent Parkinson disease between the study cohort and comparison cohort.

RESULTS

Of the 9,192 total patients, Parkinson disease developed in 0.73% during the 5-y follow-up period: 1.24% and 0.63% in the OSA and control cohorts, respectively. After censoring patients who died during the follow-up period and adjusting for socio-demographic characteristics, the hazard ratio (HR) of Parkinson disease during the 5-y follow-up period for patients with OSA was 2.26 (95% confidence interval [CI] = 1.32-3.88) compared with comparison patients. In addition, among females, the adjusted HR of Parkinson disease was 3.54 (95% CI = 1.50-8.34) for patients with OSA compared to patients without OSA. However, among males, there was no significantly increased hazard of Parkinson disease for patients with OSA compared to those without OSA.

CONCLUSIONS

Female patients with OSA were found to be at a significant risk of subsequent Parkinson disease during a 5-y follow-up period.

Tricyclic Antidepressants Amitriptyline and Desipramine Induced Neurotoxicity Associated with Parkinson's Disease

Recent studies report that a history of antidepressant use is strongly correlated with the occurrence of Parkinson's disease (PD). However, it remains unclear whether antidepressant use can be a causative factor for PD. In the present study, we examined whether tricyclic antidepressants amitriptyline and desipramine can induce dopaminergic cell damage, both in vitro and in vivo. We found that amitriptyline and desipramine induced mitochondria-mediated neurotoxicity and oxidative stress in SH-SY5Y cells. When injected into mice on a subchronic schedule, amitriptyline induced movement deficits in the pole test, which is known to detect nigrostriatal dysfunction. In addition, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta was reduced in amitriptyline-injected mice. Our results suggest that amitriptyline and desipramine may induce PD-associated neurotoxicity.

Parkinsonism following neuroleptic exposure: A double-hit hypothesis?

Drug-induced parkinsonism is caused by an offending drug and should resolve after the causative agent has been withdrawn. However, in a number of patients, symptoms persist or may even worsen over time, suggesting the development of concomitant Parkinson's disease. The prevalence estimates of Parkinson's disease after neuroleptic exposure are unexpectedly high, suggesting a causal relationship. We critically review available literature in this regard, and some pathophysiological hypotheses that might explain such a relationship are suggested. Some patients may have an undetermined genetic susceptibility to parkinsonism. We speculate that the possible neurotoxic effect of neuroleptics exerted on a susceptible dopaminergic system would lead over the long-term to a self-fostering, progressive process. Knowledge gaps and future perspectives are discussed.

Diagnostic accuracy of Parkinson's disease and atypical parkinsonism in nursing homes

INTRODUCTION

Management of Parkinson's disease (PD) and atypical parkinsonism in nursing homes depends on a timely and accurate diagnosis. However, little is known about the diagnostic accuracy of these parkinsonian syndromes in nursing homes. We examined this issue in a large group of Dutch nursing home residents.

METHODS

Twelve large nursing home organizations in the Netherlands accounting for 100 nursing homes with a total population of 5480 residents participated. Residents with PD or atypical parkinsonism were identified according to their nursing home medical chart diagnosis. Additionally, local pharmacists provided a list of all residents using antiparkinson medication. We compared the admission diagnosis to a clinical diagnosis made in the study, based upon interview and detailed neurological examination by movement disorders experts. Diagnoses were based on accepted clinical criteria for PD and atypical parkinsonism.

RESULTS

In the total population of 5480 residents, 258 had previously been diagnosed with a form of parkinsonism according to their medical record. In 53 of these residents (20.5%) we changed or rejected the diagnosis. Specifically, we found no parkinsonism in 22 of these 53 residents (8.5% of all patients with suspected parkinsonism). In the remaining 31 residents (12%), we established a new diagnosis within the parkinsonian spectrum.

CONCLUSIONS

In a large population of Dutch nursing home residents, 20% of diagnoses within the parkinsonian spectrum were inaccurate. Almost 9% of residents had inadvertently received a diagnosis of parkinsonism. Better recognition of parkinsonism in nursing homes is important, because of the consequences for management and prognosis.

Differentiating drug-induced parkinsonism from Parkinson's disease: an update on non-motor symptoms and investigations

Drug-induced parkinsonism is the second most common cause of parkinsonism after Parkinson's disease and their distinction has crucial implications in terms of management and prognosis. However, differentiating between these conditions can be challenging on a clinical ground, especially in the early stages. We therefore performed a review to ascertain whether assessment of non-motor symptoms, or use of ancillary investigations, namely dopamine transporter imaging, transcranial sonography of the substantia nigra, and scintigraphy for myocardial sympathetic innervation, can be recommended to distinguish between these conditions. Among non-motor symptoms, there is evidence that hyposmia can differentiate between patients with "pure" drug-induced parkinsonism and those with degenerative parkinsonism unmasked by an anti-dopaminergic drug. However, several issues, including smoking history and cognitive functions, can influence smell function assessment. Higher diagnostic accuracy has been demonstrated for dopamine transporter imaging. Finally, preliminary evidence exists for sympathetic cardiac scintigraphy to predict dopaminergic pathway abnormalities and to differentiate between drug-induced parkinsonism and Parkinson's disease. Imaging of the dopaminergic pathway seems to be the only, reasonably available, technique to aid the differential diagnosis between drug-induced parkinsonism and Parkinson's disease.

Increased risk of Parkinson disease following a diagnosis of neovascular age-related macular degeneration: a retrospective cohort study

PURPOSE

To investigate the risk for Parkinson disease during a 3-year follow-up period after a diagnosis of neovascular age-related macular degeneration (AMD) using a nationwide population-based dataset in Taiwan.

DESIGN

A retrospective matched-cohort study.

METHODS

We identified 877subjects with neovascular AMD as the study cohort and randomly selected 8770 subjects for a comparison cohort. Each subject was individually followed for a 3-year period to identify those who subsequently developed Parkinson disease. Stratified Cox proportional hazard regressions were performed as a means of comparing the 3-year risk of subsequent Parkinson disease between the study and comparison cohorts.

RESULTS

The incidence rate of Parkinson disease was 5.32 (95% confidence interval [CI]: 3.03-8.72) per 1000 person-years in patients with neovascular AMD and 2.09 (95% CI: 1.59-2.70) per 1000 person-years in comparison patients. The log-rank test indicated that subjects with neovascular AMD had a significantly lower 3-year Parkinson disease-free survival rate than comparison subjects (P < .001). After censoring cases in which patients died during the follow-up period and adjusting for monthly income, geographic region, hypertension, diabetes, hyperlipidemia, and coronary heart disease, the hazard ratio of Parkinson disease during the 3-year follow-up period for subjects with neovascular AMD was 2.57 (95% CI: 1.42-4.64) that of comparison subjects.

CONCLUSION

In this study, subjects with neovascular AMD were found to be at a significant risk of Parkinson disease during a 3-year follow-up period after their diagnosis among Taiwanese Chinese. Further study is needed to confirm our findings and explore the underlying pathomechanism.

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

In elderly patients, exposure to antipsychotic medication and subsequent withdrawal may lead to the development of persistent extrapyramidal symptoms, possibly including a syndrome suggested to be tardive parkinsonism. We describe a case in which withdrawal of antipsychotics was unexpectedly associated with progressive deterioration, rather than improvement, of extrapyramidal parkinsonian symptoms. Abnormal imaging of presynaptic dopamine transporters (DaTs) using single-photon emission computed tomography (SPECT) with ioflupane I 123 (DaTscan) substantially contributed to the differential diagnosis, suggesting it was likely that the patient had an underlying neurodegenerative disorder that preceded the onset of medicationinduced parkinsonian symptoms. Our report illustrates how novel findings from DaTscan may assist with diagnosing the cause of persistent parkinsonian symptoms after antipsychotic withdrawal and provide insight into the controversial concept of tardive parkinsonism.

Optimal extent of dopamine D2 receptor occupancy by antipsychotics for treatment of dopamine supersensitivity psychosis and late-onset psychosis

Several studies have proposed an optimal dopamine D2 receptor occupancy by antipsychotics (OOc) to establish optimal pharmacological treatment of schizophrenia. However, there are limitations to the use of the OOc, especially in application to patients with treatment-resistant schizophrenia, including dopamine supersensitivity psychosis (DSP) or late-onset psychosis (LOP). It has been suggested that D2 receptor density is up-regulated by chronic treatment of antipsychotics in DSP, whereas it may be low in LOP owing to age-related reduction. In estimation of the proposed OOc, these alterations have not been taken into account, which may be one of the factors contributing to the limited application of this index. We here hypothesize that there is an optimal range in the number of D2 receptors available for dopamine binding to elicit adequate neurotransmission in the treatment of patients with schizophrenia. We then estimated the OOc under the assumption that the range is constant while D2 density is variable. The results showed that the OOc and plasma level of antipsychotics increase with an increase in the D2 density but decrease with a decrease in the D2 density. That is, if the range of OOc is 65% to 78% in a standard D2 density, it becomes 82% to 89% under 2-fold up-regulated density and 42% to 63% under a 40% reduced density. The results also indicated that the reduction of the plasma antipsychotic level is greater during a given time period in patients with higher D2 density, as they need a higher antipsychotic dose to achieve the raised OOc, which would account for the clinical features of DSP, for example, acute exacerbation after a discontinuation of antipsychotics. On the other hand, in patients with lower D2 density, only a lower antipsychotic dose will achieve the OOc, and a small increase in the dose will result in a greater increase in occupancy and induce extrapyramidal adverse effects more easily. Furthermore, the reduction of the plasma antipsychotic level during the time period is smaller, which prolongs extrapyramidal adverse effects after discontinuation of antipsychotics in LOP. We also attempted to develop a strategy for the prevention and treatment of patients with DSP or LOP by focusing on D2 density.

Specific needs of dopamine neurons for stimulation in order to survive: implication for Parkinson disease

Parkinson disease (PD) is a degenerative brain disorder characterized by motor symptoms that are unequivocally associated with the loss of dopaminergic (DA) neurons in the substantia nigra (SN). Although our knowledge of the mechanisms that contribute to DA cell death in both hereditary and sporadic forms of the disease has advanced significantly, the nature of the pathogenic process remains poorly understood. In this review, we present evidence that neurodegeneration occurs when the electrical activity and excitability of these neurons is reduced. In particular, we will focus on the specific need these neurons may have for stimulation in order to survive and on the molecular and cellular mechanisms that may be compromised when this need is no longer met in PD.

Waveform analysis of tremor may help to differentiate Parkinson's disease from drug-induced parkinsonism

In this study, we analyzed the waveform characteristics of resting tremor by accelerometer recordings in patients with drug-induced parkinsonism (DIP) and Parkinson's disease (PD). We prospectively recruited 12 patients with tremulous PD and 12 patients with DIP presenting with resting tremor. Tremor was recorded from the more affected side and was recorded twice for a 60 s period in each patient. Peak frequency, amplitude and all harmonic peaks were obtained, and the asymmetry of the decay of the autocorrelation function, third momentum and time-reversal invariance were also computed using a mathematical algorithm. Among the parameters used in the waveform analysis, the harmonic ratio, time-reversal invariance and asymmetric decay of the autocorrelation function were different between PD and DIP at a statistically significant level (all p < 0.01). The total harmonic peak power and third momentum in the time series were not significantly different. The clinical characteristics of DIP patients may be similar to those of PD patients in some cases, which makes the clinical differentiation between DIP and PD challenging. Our study shows that the identification of parameters reflecting waveform asymmetry might be helpful in differentiating between DIP and PD.

Psoriasis is associated with an increased risk of parkinsonism: a population-based 5-year follow-up study

BACKGROUND

Few studies have examined the association between autoimmune diseases and parkinsonism.

OBJECTIVE

We sought to investigate the risk for parkinsonism during a 5-year follow-up period after a diagnosis of psoriasis using a population-based data set in Taiwan.

METHODS

We identified 4885 patients with psoriasis for the study cohort and randomly selected 24,425 patients as a control cohort. Each subject was individually followed up for a 5-year period to identify those who subsequently developed parkinsonism.

RESULTS

Stratified Cox proportional hazards regression showed that the adjusted hazard ratio for parkinsonism during the 5-year follow-up period for patients with psoriasis was 1.74 (95% confidence interval 1.35-2.20) that of control patients. Furthermore, the adjusted hazard ratios for parkinsonism within the 5-year follow-up period after the index date for subjects with psoriasis were similar between both sexes (1.78 and 1.66 for men and women, respectively).

LIMITATION

Our data set did not provide detailed information on the severity of psoriasis, or individual factors such as cigarette smoking, alcohol consumption, body mass index, and dietary patterns.

CONCLUSION

Patients with psoriasis were found to be at a significant risk of parkinsonism during a 5-year follow-up.

Psychotropic medications and falls in nursing homes: a cross-sectional study

BACKGROUND

Psychotropic medications are very frequently used in nursing homes and have been associated with falls. Little is known on the potential differences between types and subtypes of these medications, and also regarding different prescription patterns.

METHODS

Data from 4502 residents living in 41 nursing homes belonging to a Spanish private chain were collected during a study period of 1 month and analyzed. Frequency of injurious and noninjurious falls were investigated for the following groups of psychotropic medications: typical neuroleptics; atypical neuroleptics; antidepressants; short and middle half-life benzodiazepines (BZD); long half-life BZD; BZD (of any type) administered only if needed; other hypnotic, sedative or anxiolytic drugs; cholinesterase inhibitors, and memantine. OR (95% CI) were calculated using regression analysis adjusted for age, sex, number of medications, physical restraint, and cognitive performance.

RESULTS

Mean age (SD) was 84.3 (8.6) and 73.4% of the subjects were female. Psychotropic medication was prescribed to 2987 residents (66.3%), and there were 490 falls. Total falls were associated with use of atypical neuroleptics (OR 1.50, CI 1.17‒1.94), antidepressants (OR 1.36, CI 1.03‒1.78), short and middle half-life BZD (OR 1.27, CI 1.00‒1.60), long half-life BZD (OR 1.65, CI 1.14‒2.38), cholinesterase inhibitors (OR 1.42, CI 1.05‒1.92), and memantine (OR 1.90, CI 1.32‒2.74). Injurious falls were associated with typical neuroleptics (OR 1.77, CI 0.99‒3.17), atypical neuroleptics (OR 1.64, CI 1.11‒2.44), and long half-life BZD (OR 2.57, CI 1.56‒4.25). The use of 2 or more psychotropics in combination was also associated with a significant increase of total falls and injurious falls.

CONCLUSIONS

Psychotropic medications were highly prescribed in the studied sample and were associated with falls. The most unsafe profile was detected for long half-life BZD, neuroleptics, and psychotropics in combination.

Diagnostic accuracy of 123 I-FP-CIT SPECT in diagnosing drug-induced parkinsonism: a prospective study

INTRODUCTION

Drug-induced parkinsonism is a major type of parkinsonism in our setting. Symptoms usually disappear after discontinuation of the drug. However, they may persist in patients with a variant known as subclinical drug-exacerbated parkinsonism; early identification of this entity has important prognostic and therapeutic implications. The most widely used complementary test in this diagnosis is single-photon emission computed tomography with ioflupane ((123)I), also known as (123)I-FP-CIT SPECT. The aim of our study is to verify its diagnostic accuracy.

METHODS

We designed a prospective study of patients with drug-induced parkinsonism in which, after discontinuing the drug and undergoing a (123)I-FP-CIT SPECT scan, patients would be monitored for at least 6 months. Patients were categorised as having iatrogenic parkinsonism if symptoms disappeared, or as having subclinical drug-exacerbated parkinsonism if they persisted. Lastly, we verified concordance between the clinical diagnosis and results from the (123)I- FP-CIT SPECT scan.

RESULTS

The sample included 19 patients. The most commonly prescribed drug class was neuroleptic agents. For the diagnosis of both subgroups, (123)I-FP-CIT SPECT showed a sensitivity of 66.7%, specificity and positive predictive value of 100%, a negative predictive value of 86.7%, and a negative likelihood ratio of 0.33.

CONCLUSIONS

Although the study needs to be repeated in a larger sample of patients, (123)I-FP-CIT SPECT is useful in the diagnosis of drug-induced parkinsonism since it is a very precise tool for identifying patients with that illness.

NSAID use and risk of Parkinson disease: a population-based case-control study

BACKGROUND

Previous epidemiologic studies have produced inconsistent findings regarding the association between the use of non-steroidal anti-inflammatory drugs (NSAIDs) and the risk of Parkinson disease (PD).

METHODS

We conducted a case-control analysis using the General Practice Research Database. Cases (≥40 years) had a new diagnosis of PD between 1994 and 2009. We matched four controls to each PD case on age, sex, general practice, and index date. Use of NSAIDs, aspirin, and acetaminophen was stratified by exposure timing and duration for both cases and controls. We calculated odds ratios (OR) using conditional logistic regression. For additional analyses, the index date was brought backward 1, 2, and 3 years, respectively.

RESULTS

We identified 4026 cases with an incident idiopathic PD diagnosis and 15,969 matched controls. Compared with patients without any previous prescription for NSAIDs, those with prior use had no increased risk of a PD diagnosis (OR 1.07, 95% CI 0.99-1.16). Long-term use (≥15 prescriptions) was associated with a slightly lower PD risk (adjusted OR 0.94, 95% CI 0.83-1.07). The relative PD risks of the use of aspirin or acetaminophen were not materially higher (PD risk of long-term use: adjusted ORs 1.16, 95% CI 1.03-1.30 and 1.15, 95% CI 1.02-1.30, respectively) compared with those for non-users. The risk estimate diminished toward the null in subsequent analyses with shifted index dates.

CONCLUSION

In this large observational study with data from the UK primary care, the long-term use of NSAIDs, aspirin, or acetaminophen was not associated with a substantially altered risk of developing PD.

Neuroglia in neurodegeneration

Neuroglial cells are fundamental for control of brain homeostasis and they represent the intrinsic brain defence system. All forms in neuropathology therefore inevitably involve glia. The neurodegenerative diseases disrupt connectivity within brain circuits affecting neuronal-neuronal, neuronal-glial and glial-glial contacts. In addition neurodegenerative processes trigger universal and conserved glial reactions represented by astrogliosis and microglial activation. The complex of recently acquired knowledge allows us to regard the neurodegenerative diseases as primarily gliodegenerative processes, in which glial cells determine the progression and outcome of neuropathological process.

Glial Cells as Players in Parkinsonism: The “Good,” the “Bad,” and the “Mysterious” Glia

The role of glia in Parkinson's disease (PD) is very interesting because it may open new therapeutic strategies in this disease. Traditionally it has been considered that astrocytes and microglia play different roles in PD: Astroglia are considered the “good” glia and have traditionally been supposed to be neuroprotective due to their capacity to quench free radicals and secrete neurotrophic factors, whereas microglia, considered the “bad” glia, are thought to play a critical role in neuroinflammation. The proportion of astrocytes surrounding dopamine (DA) neurons in the substantia nigra, the target nucleus for neurodegeneration in PD, is the lowest for any brain area, suggesting that DA neurons are more vulnerable in terms of glial support than any neuron in other brain areas. Astrocytes are critical in the modulation of the neurotoxic effects of many toxins that induce experimental parkinsonism and they produce substances in vitro that could modify the effects of L-DOPA from neurotoxic to neurotrophic. There is a great interest in the role of inflammation in PD, and in the brains of these patients there is evidence for microglial production of cytokines and other substances that could be harmful to neurons, suggesting that microglia of the substantia nigra could be actively involved, primarily or secondarily, in the neurodegeneration process. There is, however, evidence in favor of the role of neurotoxic diffusible signals from microglia to DA neurons. More recently a third glial player, oligodendroglia, has been implicated in the pathogenesis of PD. Oligodendroglia play a key role in myelination of the nervous system. Recent neuropathological studies suggested that the nigrostriatal dopamine neurons, which were considered classically as the primary target for neurodegeneration in PD, degenerate at later stages than other neurons with poor myelination. Therefore, the role of oligodendroglia, which also secrete neurotrophic factors, has entered the center of interest of neuroscientists.

Viral parkinsonism

Parkinson's disease is a debilitating neurological disorder that affects 1-2% of the adult population over 55 years of age. For the vast majority of cases, the etiology of this disorder is unknown, although it is generally accepted that there is a genetic susceptibility to any number of environmental agents. One such agent may be viruses. It has been shown that numerous viruses can enter the nervous system, i.e. they are neurotropic, and induce a number of encephalopathies. One of the secondary consequences of these encephalopathies can be parkinsonism, that is both transient as well as permanent. One of the most highlighted and controversial cases of viral parkinsonism is that which followed the 1918 influenza outbreak and the subsequent induction of von Economo's encephalopathy. In this review, we discuss the neurological sequelae of infection by influenza virus as well as that of other viruses known to induce parkinsonism including Coxsackie, Japanese encephalitis B, St. Louis, West Nile and HIV viruses.