Review of the role of the endogenous opioid and melanocortin systems in the restless legs syndrome.

Restless legs syndrome (RLS) is responsive to opioid, dopaminergic and iron-based treatments. Receptor blocker studies in RLS patients suggest that the therapeutic efficacy of opioids is specific to the opioid receptor and mediated indirectly through the dopaminergic system. An RLS autopsy study reveals decreases in endogenous opioids, ß-endorphin and perhaps Met-enkephalin in the thalamus of RLS patients. A total opioid receptor knock-out (mu, delta and kappa) and a mu-opioid receptor knock-out mouse model of RLS show circadian motor changes akin to RLS and, although both models show sensory changes, the mu-opioid receptor knock mouse shows circadian sensory changes closest to those seen in idiopathic RLS. Both models show changes in striatal dopamine, anaemia and low serum iron. However, only in the total receptor knock-out mouse do we see the decreases in serum ferritin that are normally found in RLS. There are also decreases in serum iron when wild-type mice are administered a mu-opioid receptor blocker. In addition, the mu-opioid receptor knock-out mouse also shows increases in striatal zinc paralleling similar changes in RLS. Adrenocorticotropic hormone and α-melanocyte stimulating hormone are derived from pro-opiomelanocortin as is ß-endorphin. However, they cause RLS-like symptoms and periodic limb movements when injected intraventricularly into rats. These results collectively suggest that an endogenous opioid deficiency is pathogenetic to RLS and that an altered melanocortin system may be causal to RLS as well.

A Randomized Phase 2 KINETIC Trial Evaluating SAGE-324/BIIB124 in Individuals with Essential Tremor.

BACKGROUND: SAGE-324/BIIB124 is an investigational positive allosteric modulator of GABAA receptors. OBJECTIVE: KINETIC (NCT04305275), a double-blind, randomized, placebo-controlled, phase 2 study, evaluated SAGE-324/BIIB124 in individuals with essential tremor (ET). METHODS: Individuals aged 18 to 80 years were randomly assigned 1:1 to orally receive 60 mg of SAGE-324/BIIB124 or placebo once daily for 28 days. The primary endpoint was change from baseline in The Essential Tremor Rating Assessment Scale-Performance Subscale (TETRAS-PS) Item 4 (upper-limb tremor) at day 29 with SAGE-324/BIIB124 versus placebo. RESULTS: Between May 2020 and February 2021, 69 U.S. participants were randomly assigned to receive SAGE-324/BIIB124 (n = 34) or placebo (n = 35). There was a significant reduction from baseline in TETRAS-PS Item 4 at day 29 with SAGE-324/BIIB124 versus placebo (least squares mean [standard error]: -2.31 [0.401] vs. -1.24 [0.349], P = 0.0491). The most common treatment-emergent adverse events included somnolence, dizziness, fatigue, and balance disorder. CONCLUSION: These results support further development of SAGE-324/BIIB124 for potential ET treatment. © 2024 Sage Therapeutics, Inc and The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The Self-Administered Screening Questionnaire for Parkinson's Disease-Associated Psychosis (SASPAP).

BACKGROUND: Psychosis is a common manifestation of Parkinson's disease (PD), and a major source of caregiver burden, nursing home placement, and mortality. Psychosis symptoms are often not volunteered during the clinic visit because of embarrassment or lack of insight, and there is no validated screening scale. We compare a new self-administered psychosis screening questionnaire against the Parkinson's Disease Psychosis Scale (PDPS) and physician interview as the gold standard assessments. OBJECTIVE: To create and validate the Self-Administered Screening Questionnaire for PD-Associated Psychosis (SASPAP). METHODS: The questionnaire was developed through a modified Delphi method by a committee of two neurologists, a psychiatrist, a patient, and patient advocate and underwent several rounds of revisions, including patient ß-testing. It was provided by staff at intake to 250 consecutive patients diagnosed with PD, at the Methodist Hospital Movement Disorders Clinic, and separately to their caregivers when available. Later, the PDPS and a general psychosis interview were administered by PD specialists without knowledge of the screening questionnaire responses. RESULTS: Two hundred and fifty consecutive patients with PD (mean age, 68.6 ± 7.0; mean age of PD onset, 62.7 ± 10.5 years; 35.2% female) were included. The screening questionnaire was positive for psychosis (any of the four questions positive) in 33.6% of patients. Compared to the gold standard, the SASPAP sensitivity was 87.8% and the specificity 92.3%. CONCLUSION: This four-question self-administered screening questionnaire for PD psychosis demonstrated high diagnostic accuracy compared with the gold standard assessments and can be self-completed at visit intake. © 2023 International Parkinson and Movement Disorder Society.

THN 102 for Excessive Daytime Sleepiness Associated with Parkinson's Disease: A Phase 2a Trial.

BACKGROUND: Excessive daytime sleepiness (EDS) is a frequent and disabling symptom of Parkinson's disease (PD) without approved treatment. THN102 is a novel combination drug of modafinil and low-dose flecainide. OBJECTIVE: The aim of this study is to evaluate the safety and efficacy of THN102 in PD patients with EDS. METHODS: The method involved a randomized, double-blind, placebo-controlled, crossover trial testing two doses of THN102 (200 mg/d modafinil with 2 mg/d [200/2] or 18 mg/d flecainide [200/18]) versus placebo; 75 patients were exposed to treatment. The primary endpoint was safety. The primary efficacy outcome was the change in Epworth Sleepiness Scale (ESS) score. RESULTS: Both doses of THN102 were well tolerated. ESS significantly improved with THN102 200/2 (least square means vs. placebo [95% confidence interval, CI]: -1.4 [-2.49; -0.31], P = 0.012) but did not change significantly with the 200/18 dosage. CONCLUSIONS: THN102 was well tolerated and showed a signal of efficacy at the 200/2 dose, supporting further development for the treatment of EDS in PD. © 2021 International Parkinson and Movement Disorder Society.

Exploratory cross-over, trial of augmented RLS with the dopamine receptor 1/5 antagonist ecopipam D1/D5 antagonist ecopipam for augmented RLS.

BACKGROUND: Restless legs syndrome (RLS) is a common condition that initially responds dramatically to dopaminergic therapy. Over time, however, dopaminergics cause augmentation, where symptoms occur earlier and intensify. Animal models suggest this may result from increased dopamine receptor type-1 affinity in the spinal cord. Ecopipam is a potent, specific dopamine-1/5 receptor antagonist. METHODS: We performed a small (N = 10) exploratory placebo controlled, cross-over safety trial of ecopipam (25-100 mg/day) for patients with augmented RLS currently taking dopamine agonists. RESULTS: Ecopipam was well tolerated with sedation being the most common adverse event in drug and placebo. Safety scales and serology data were similar to placebo. The study was not powered to demonstrate efficacy and exploratory efficacy data showed no significant improvement compared to placebo, but RLS diaries, the international RLS rating scale, and clinical global impressions all favored drug. No subject worsened on drug or demonstrated rebound worsening after drug discontinuation. CONCLUSION: Ecopipam was safe and well tolerated in this initial study for RLS. Given the lack of alternate options, larger efficacy studies for augmented RLS, and potentially de novo RLS are justified.

A Multi-center Genome-wide Association Study of Cervical Dystonia.

BACKGROUND: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility. OBJECTIVE: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach. METHODS: We performed a genome-wide association study using cervical dystonia samples from the Dystonia Coalition. Logistic and linear regressions, including age, sex, and population structure as covariates, were employed to assess variant- and gene-based genetic associations with disease status and age at onset. We also performed a replication study for an identified genome-wide significant signal. RESULTS: After quality control, 919 cervical dystonia patients compared with 1491 controls of European ancestry were included in the analyses. We identified one genome-wide significant variant (rs2219975, chromosome 3, upstream of COL8A1, P-value 3.04 × 10-8 ). The association was not replicated in a newly genotyped sample of 473 cervical dystonia cases and 481 controls. Gene-based analysis identified DENND1A to be significantly associated with cervical dystonia (P-value 1.23 × 10-6 ). One low-frequency variant was associated with lower age-at-onset (16.4 ± 2.9 years, P-value = 3.07 × 10-8 , minor allele frequency = 0.01), located within the GABBR2 gene on chromosome 9 (rs147331823). CONCLUSION: The genetic underpinnings of cervical dystonia are complex and likely consist of multiple distinct variants of small effect sizes. Larger sample sizes may be needed to provide sufficient statistical power to address the presumably multi-genic etiology of cervical dystonia. © 2021 International Parkinson and Movement Disorder Society.

Restless abdomen: a spectrum or a phenotype variant of restless legs syndrome?

BACKGROUND: With the growing awareness of restless legs syndrome (RLS), sensory disorders similar to RLS but initially confined to the arms, abdomen, and perineum have been reported. One of them is restless abdomen, which refers to a restless sensation in abdomen. Our study is designed to evaluate the clinical phenotype of restless abdomen and investigate its relationship with RLS. METHODS: We enrolled 10 patients with restless abdomen according to RLS diagnostic criteria, excluding the requiring of leg involvement. Laboratory examinations were performed to exclude mimics and notable comorbidities. RESULTS: All 10 patients had RLS like symptoms in the abdomen and otherwise satisfied all other RLS diagnostic criteria, and responded to dopaminergic therapy. CONCLUSIONS: Neurologists and gastroenterologists should be aware that RLS-related restlessness can occur in extra-leg anatomy in the absence of episodes of worsening or augmentation of restlessness.

A Randomized Trial of Focused Ultrasound Thalamotomy for Essential Tremor.

BACKGROUND: Uncontrolled pilot studies have suggested the efficacy of focused ultrasound thalamotomy with magnetic resonance imaging (MRI) guidance for the treatment of essential tremor. METHODS: We enrolled patients with moderate-to-severe essential tremor that had not responded to at least two trials of medical therapy and randomly assigned them in a 3:1 ratio to undergo unilateral focused ultrasound thalamotomy or a sham procedure. The Clinical Rating Scale for Tremor and the Quality of Life in Essential Tremor Questionnaire were administered at baseline and at 1, 3, 6, and 12 months. Tremor assessments were videotaped and rated by an independent group of neurologists who were unaware of the treatment assignments. The primary outcome was the between-group difference in the change from baseline to 3 months in hand tremor, rated on a 32-point scale (with higher scores indicating more severe tremor). After 3 months, patients in the sham-procedure group could cross over to active treatment (the open-label extension cohort). RESULTS: Seventy-six patients were included in the analysis. Hand-tremor scores improved more after focused ultrasound thalamotomy (from 18.1 points at baseline to 9.6 at 3 months) than after the sham procedure (from 16.0 to 15.8 points); the between-group difference in the mean change was 8.3 points (95% confidence interval [CI], 5.9 to 10.7; P<0.001). The improvement in the thalamotomy group was maintained at 12 months (change from baseline, 7.2 points; 95% CI, 6.1 to 8.3). Secondary outcome measures assessing disability and quality of life also improved with active treatment (the blinded thalamotomy cohort)as compared with the sham procedure (P<0.001 for both comparisons). Adverse events in the thalamotomy group included gait disturbance in 36% of patients and paresthesias or numbness in 38%; these adverse events persisted at 12 months in 9% and 14% of patients, respectively. CONCLUSIONS: MRI-guided focused ultrasound thalamotomy reduced hand tremor in patients with essential tremor. Side effects included sensory and gait disturbances. (Funded by InSightec and others; ClinicalTrials.gov number, NCT01827904.).

Long-term safety and efficacy of deutetrabenazine for the treatment of tardive dyskinesia.

OBJECTIVE: To evaluate the long-term safety and efficacy of deutetrabenazine in patients with tardive dyskinesia (TD). METHOD: Patients with TD who completed the 12 week, phase 3, placebo-controlled trials were eligible to enter this open-label, single-arm study. The open-label study consisted of a 6 week dose-escalation phase and a long-term maintenance phase (clinic visits at Weeks 4, 6 and 15, and every 13 weeks until Week 106). Patients began deutetrabenazine at 12 mg/day, titrating up to a dose that was tolerable and provided adequate dyskinesia control, based on investigator judgement, with a maximum allowed dose of 48 mg/day (36 mg/day for patients taking strong cytochrome P450 2D6 (CYP2D6) inhibitors). Safety measures included incidence of adverse events (AEs) and scales used to monitor parkinsonism, akathisia/restlessness, anxiety, depression, suicidality and somnolence/sedation. Efficacy endpoints included the change in Abnormal Involuntary Movement Scale (AIMS) score (items 1 to 7) from baseline and the proportion of patients rated as 'Much Improved' or 'Very Much Improved' on the Clinical Global Impression of Change. RESULTS: A total of 343 patients enrolled in the extension study, and there were 331 patient-years of exposure in this analysis. The exposure-adjusted incidence rates of AEs with long-term treatment were comparable to or lower than those observed in the phase 3 trials. The mean (SE) change in AIMS score was -4.9 (0.4) at Week 54 (n = 146), - 6.3 (0.7) at Week 80 (n = 66) and -5.1 (2.0) at Week 106 (n = 8). CONCLUSIONS: Overall, long-term treatment with deutetrabenazine was efficacious, safe, and well tolerated in patients with TD. TRIAL REGISTRATION NUMBER: NCT02198794.

Restless legs syndrome in end stage renal disease patients undergoing hemodialysis.

BACKGROUND: The prevalence of Restless legs syndrome (RLS) in End Stage Renal Disease (ESRD) patients is higher than that in the general population. However, the associations of RLS within the ESRD population are inconsistent and RLS is usually neglected in dialysis centers, although it impairs the life quality among ESRD patients. We aim to investigate the prevalence of RLS in patients with ESRD undergoing maintenance hemodialysis and evaluate the risk factors of developing RLS and the effect of RLS on quality of life among ESRD patients. METHODS: ESRD patients undergoing maintenance hemodialysis in Shanghai General Hospital dialysis unit from July 2016 to October 2016 were enrolled in the study. RLS was diagnosed according to the criteria of the International Restless Legs Syndrome Study Group (IRLSSG). IRLSSG Severity Scale was used to evaluate the severity of RLS. Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality, and Hospital Anxiety and Depression Scale (HADS) was used to estimate anxiety and depression. Serologic and historic variables were analyzed to determine predictors of RLS in the ESRD population. RESULTS: A total of 137 ESRD patients were enrolled. The prevalence of RLS among the ESRD patients was 20.44%. The risk of RLS was increased significantly in females (OR = 2.729, p = 0.032) and daily alcohol drinkers (OR = 4.716, p = 0.022). RLS increased the risks of sleep disorders (25/28, 89.3% vs 73/109, 67.0%, p = 0.02) and sedative hypnotics intake (7/28, 25.0% vs 10/109, 9.2%, p = 0.047) and impaired the sleep quality (7/109 vs 11/28, p = 0.001) according to PSQI sum scores. CONCLUSION: A high RLS prevalence among the ESRD patients undergoing hemodialysis was confirmed. ESRD patients who are women and drinking alcohol have a higher risk of RLS. The sleep quality was significantly impaired and sleeping medication use was more common among the ESRD patients with RLS.

Treating Hallucinations and Delusions Associated With Parkinson's Disease Psychosis.

PURPOSE OF REVIEW: We discuss features of Parkinson's disease psychosis (PDP) including symptomology and pathophysiology. Treatment options, including non-pharmacologic strategies, dose reduction of offending agents, and the addition of non-dopaminergic antipsychotics, are addressed. The efficacy of second-generation antipsychotics and novel agents is examined. RECENT FINDINGS: Pimavanserin, a 5-HT2A/C receptor inverse agonist with no other receptor activity, has shown efficacy and tolerability and is now FDA approved for PDP treatment. Research into novel targets is ongoing. PDP is a morbid complication of Parkinson's disease with complex incompletely understood mechanisms. Treatment is directed towards mitigation of psychosis without worsening of motor features.

Clinical and demographic characteristics related to onset site and spread of cervical dystonia.

BACKGROUND: Clinical characteristics of isolated idiopathic cervical dystonia such as onset site and spread to and from additional body regions have been addressed in single-site studies with limited data and incomplete or variable dissociation of focal and segmental subtypes. The objectives of this study were to characterize the clinical characteristics and demographics of isolated idiopathic cervical dystonia in the largest standardized multicenter cohort. METHODS: The Dystonia Coalition, through a consortium of 37 recruiting sites in North America, Europe, and Australia, recruited 1477 participants with focal (60.7%) or segmental (39.3%) cervical dystonia on examination. Clinical and demographic characteristics were evaluated in terms of the body region of dystonia onset and spread. RESULTS: Site of dystonia onset was: (1) focal neck only (78.5%), (2) focal onset elsewhere with later segmental spread to neck (13.3%), and (3) segmental onset with initial neck involvement (8.2%). Frequency of spread from focal cervical to segmental dystonia (22.8%) was consistent with prior reports, but frequency of segmental onset with initial neck involvement was substantially higher than the 3% previously reported. Cervical dystonia with focal neck onset, more than other subtypes, was associated with spread and tremor of any type. Sensory tricks were less frequent in cervical dystonia with segmental components, and segmental cervical onset occurred at an older age. CONCLUSIONS: Subgroups had modest but significant differences in the clinical characteristics that may represent different clinical entities or pathophysiologic subtypes. These findings are critical for design and implementation of studies to describe, treat, or modify disease progression in idiopathic isolated cervical dystonia. © 2016 International Parkinson and Movement Disorder Society.

Does idiopathic restless legs syndrome delay onset and reduce severity of Parkinson's disease: a pilot study.

Parkinson's disease (PD) populations show that about 20% of patients meet criteria for restless legs syndrome (RLS). Nevertheless, pathological differences suggest RLS may actually prevent PD. Over 15 years, we collected patients with idiopathic RLS preceding onset of PD, as defined by onset of RLS greater than 5 years before motor symptoms of PD, or a family history of RLS and onset of RLS at least 1 year before PD. We then compared these to a control group of PD without RLS for demographics, age of onset, motor progression, dyskinesia, L-dopa equivalent dose, and PD phenotype at onset. The RLS/PD group (N = 36) had 13 females with 18 having a positive family history of RLS and six with a family history of PD. The PD control group (N = 36) had 10 females with 1 having a family history of RLS and nine with family history of PD. Age at motor onset of PD in the RLS/PD was older (64.15 ± 6.44 years vs. 56.81 ± 10.68) than for controls with PD (p < 0.001). After correcting for other risk factors and duration of follow-up, patients with idiopathic PD (21/36) developed dyskinesia more than RLS/PD (4/32) at final visit (p = 0.01). Our data suggest that idiopathic RLS may delay the onset of PD, reduce dyskinesia occurrence, and possibly reduce progression of PD.

Sleep/wake problems in Parkinson's disease: pathophysiology and clinicopathologic correlations.

In his initial description of shaking palsy, James Parkinson first noted that sleep became disturbed with advancing paralysis agitans. More recent studies have confirmed that the majority of patients with Parkinson's disease (PD) suffer from some sleep disturbances. This can manifest as difficulty in falling or staying asleep, fractionated sleep, specific parasomnias, and daytime sleepiness. In this article, we will explore the pathophysiology of these varied sleep disorders. In most cases, however, the definitive etiology is debated, and phenotypes are often felt to be multifactorial. Some of these may be associated with dopaminergic dysfunction, some presumed to arise from varied non-dopaminergic PD pathology, and some from PD treatments.

Genome-wide association study identifies novel restless legs syndrome susceptibility loci on 2p14 and 16q12.1.

Restless legs syndrome (RLS) is a sensorimotor disorder with an age-dependent prevalence of up to 10% in the general population above 65 years of age. Affected individuals suffer from uncomfortable sensations and an urge to move in the lower limbs that occurs mainly in resting situations during the evening or at night. Moving the legs or walking leads to an improvement of symptoms. Concomitantly, patients report sleep disturbances with consequences such as reduced daytime functioning. We conducted a genome-wide association study (GWA) for RLS in 922 cases and 1,526 controls (using 301,406 SNPs) followed by a replication of 76 candidate SNPs in 3,935 cases and 5,754 controls, all of European ancestry. Herein, we identified six RLS susceptibility loci of genome-wide significance, two of them novel: an intergenic region on chromosome 2p14 (rs6747972, P = 9.03 × 10(-11), OR = 1.23) and a locus on 16q12.1 (rs3104767, P = 9.4 × 10(-19), OR = 1.35) in a linkage disequilibrium block of 140 kb containing the 5'-end of TOX3 and the adjacent non-coding RNA BC034767.

Paraspinal muscle asymmetry in Parkinson's disease.

Lateral postural deviation in Parkinson's disease (PD) is not uncommon but has never been radiographically queried to evaluate for specific muscle anatomy. Ten subjects (9 female) were identified with paraspinal asymmetry on examination and MRI. Relative atrophy was seen diffusely in all paraspinal muscles (psoas, interspinalis, quadratus, multifidus, longissimus and ileocostalis). The quadratus, multifidus, longissimus and ileocostalis were the most asymmetric and equally involved. The interspinalis was less asymmetric, whereas the psoas was almost never asymmetric. Fatty infiltrates, consistent with radiographic myopathic degeneration, were often seen in the atrophic muscles. In 8/10 cases, the side of PD symptom onset demonstrated the greatest atrophy. Lateral postural deviation appears to result from ipsilateral paraspinal atrophy with fatty infiltration. Correlation with the most affected side suggests causality.

The Clinician's Tardive Inventory (CTI): A New Clinical Tool for Documenting and Rating Tardive Dyskinesia.

Objective: Current clinician-rated tardive dyskinesia (TD) symptom scales have not addressed the expanding clinical signs and functional impact of TD. The study objective was to develop and test the reliability of a new integrated instrument.Methods: A movement disorder neurologist devised the outline of the rating scale. A Steering Committee (5 neurologists and 2 psychiatrists) provided revisions until consensus was reached. The Clinician's Tardive Inventory (CTI) assesses abnormal movements of the eye/eyelid/face, tongue/mouth, jaw, and limb/trunk; complex movements defined as complicated movements different from simple patterned movements or postures; and vocalizations. The CTI rates frequency of symptoms from 0 to 3 (ranging from absent to constant). Functional impairments, including activities of daily living (ADL), social impairment, symptom distress, and physical harm, are rated 0-3 (ranging from unawareness to severe impact). The CTI underwent interrater and test-retest reliability testing between February and June 2022 based on videos and accompanying vignettes, which were reviewed by 2 movement disorder specialists to determine adequacy. Four clinicians rated each video/vignette. Interrater agreement was analyzed via 2-way random-effects intraclass correlation (ICC), and test-retest agreement was assessed utilizing the Kendall tau-b.Results: Forty-five video/vignettes were assessed for interrater reliability and 16 for test-retest reliability. The most prevalent movements were those of the tongue and mouth (77.8%) and jaw (55.6%). ICCs for movement frequency for anatomic symptoms were as follows: anatomic symptom summary score 0.92, abnormal eye movement 0.89, abnormal tongue/mouth movement 0.91, abnormal jaw movement 0.89, abnormal limb movement 0.76, complex movement 0.87, and abnormal vocalization 0.77; ICCs for functional impairments were as follows: total impairment score 0.92, physical harm 0.82, social embarrassment 0.88, ADLs 0.83, and symptom bother 0.92; Retests were conducted a mean (SD) of 15 (3) days later with correlation coefficients ranging from 0.66 to 0.87.Conclusions: The CTI is a new integrated instrument with proven reliability in assessing TD signs and functional impacts. Future validation study is warranted.

Genome-wide meta-analyses of restless legs syndrome yield insights into genetic architecture, disease biology and risk prediction.

Restless legs syndrome (RLS) affects up to 10% of older adults. Their healthcare is impeded by delayed diagnosis and insufficient treatment. To advance disease prediction and find new entry points for therapy, we performed meta-analyses of genome-wide association studies in 116,647 individuals with RLS (cases) and 1,546,466 controls of European ancestry. The pooled analysis increased the number of risk loci eightfold to 164, including three on chromosome X. Sex-specific meta-analyses revealed largely overlapping genetic predispositions of the sexes (rg = 0.96). Locus annotation prioritized druggable genes such as glutamate receptors 1 and 4, and Mendelian randomization indicated RLS as a causal risk factor for diabetes. Machine learning approaches combining genetic and nongenetic information performed best in risk prediction (area under the curve (AUC) = 0.82-0.91). In summary, we identified targets for drug development and repurposing, prioritized potential causal relationships between RLS and relevant comorbidities and risk factors for follow-up and provided evidence that nonlinear interactions are likely relevant to RLS risk prediction.

Clozapine: Efficacy for Parkinson Disease psychosis in patients refractory to pimavanserin.

Pimavanserin is the only approved drug for Parkinson's disease psychosis (PDP) and is an increasingly used therapy where available. Clozapine has proven efficacy for PDP but is much less commonly used secondary to frequent blood tests to monitor for agranulocytopenia. We identified 27 patients with PDP (72 ± 7.3 years, 11 (41%) female), with an inadequate response to pimavanserin, who subsequently started clozapine. The final mean daily dose of clozapine was 49.5 mg [range 25-100] at night, and mean duration of follow-up was 17 months [range: 2-50 months]. Patients reported clozapine to be markedly effective in 11 (41%), moderately effective in 6 (22%), somewhat effective in 5 (18%). No patient reported that it was ineffective, but 5 (19%) had inadequate follow-up. Clozapine should be considered in pimavanserin refractory psychosis.