Parkinson's Disease Psychosis Research Articles

Predictors for early-onset psychotic symptoms in patients newly diagnosed with Parkinson's disease without psychosis at baseline: A 5-year cohort study.

To investigate the risk factors for early-onset psychosis in Parkinson's disease (PD) in a cohort of patients from the Parkinson's Progression Markers Initiative. Longitudinal data on motor and non-motor features, dopamine transporter (DAT) imaging, and cerebrospinal fluid (CSF) measurements were collected. The survival probability of psychotic symptoms, potential risk factors for psychosis development over a 5-year follow-up period, and the performance of the prediction model were evaluated. Among the 338 newly diagnosed patients with PD, 83 developed psychotic symptoms. Gastrointestinal autonomic dysfunction, presence of probable rapid-eye-movement sleep behavior disorder, and the ratio Aβ42: total-tau could independently predict onset of psychosis in PD (hazard ratio (HR) = 1.157, 95% confidence interval (CI) 1.022-1.309, p = 0.021, HR = 2.596, 95% CI 1.287-5.237, p = 0.008, and HR = 0.842, 95% CI 0.723-0.980, p = 0.027, respectively). The combined model integrating baseline clinical predictors, DAT imaging, and CSF measurements achieved better sensitivity than the clinical predictors alone (area under the curve = 0.770 [95% CI 0.672-0.868] vs. 0.714 [95% CI 0.625-0.802], p = 0.098). We identified clinical and CSF predictors of early-onset psychosis in patients with PD. Our study provides evidence and implications for prognostic stratification and therapeutic approaches for PD psychosis.

HOMER1 Polymorphism and Parkinson's Disease-Psychosis: Is there an Association?

Homer1, a postsynaptic protein coded by the HOMER1 gene, presumably has a role in homeostatic plasticity that dampens neuronal responsiveness when the input activity is too high. HOMER1 polymorphism has been studied in major psychiatric disorders such as schizophrenia. The objective of this study is to investigate if polymorphisms of the HOMER1 gene are associated with psychosis in Parkinson's disease (PD-P). One hundred patients with Parkinson's disease (PD) and 100 healthy controls were enrolled consecutively in a PD-P biomarker study at the National Institute of Mental Health and Neurosciences, Bangalore, India. Of the 100 PD patients, 50 had psychosis (PD-P) and 50 did not have psychosis (PD-NP). Two single-nucleotide polymorphisms of HOMER1 (rs4704559 and rs4704560) were analyzed from the DNA isolated from peripheral blood. The allele and genotype frequencies in the PD-P and PD-NP groups were compared. Analysis of HOMER1 rs4704560 revealed a significant difference in both genotype and allele levels between PD-P and PD-NP groups. There was an overrepresentation of T-allele (42% vs. 16%; P < 0.001) and TT genotype (24% vs. 6%; P < 0.001) in the PD-P group compared to PD-NP group. There was no significant difference between PD-P and PD-NP groups when various genotypes and allele frequencies related to HOMER1 rs4704559 were compared. PD-P is probably associated with overrepresentation of T-allele of HOMER1 rs4704560, and larger studies are warranted to confirm our results.

Neurophysiological treatment effects of mesdopetam, pimavanserin and clozapine in a rodent model of Parkinson's disease psychosis

Psychosis in Parkinson's disease is a common phenomenon associated with poor outcomes. To clarify the pathophysiology of this condition and the mechanisms of antipsychotic treatments, we have here characterized the neurophysiological brain states induced by clozapine, pimavanserin, and the novel prospective antipsychotic mesdopetam in a rodent model of Parkinson's disease psychosis, based on chronic dopaminergic denervation by 6-OHDA lesions, levodopa priming, and the acute administration of an NMDA antagonist. Parallel recordings of local field potentials from eleven cortical and sub-cortical regions revealed shared neurophysiological treatment effects for the three compounds, despite their different pharmacological profiles, involving reversal of features associated with the psychotomimetic state, such as a reduction of aberrant high-frequency oscillations in prefrontal structures together with a decrease of abnormal synchronization between different brain regions. Other drug-induced neurophysiological features were more specific to each treatment, affecting network oscillation frequencies and entropy, pointing to discrete differences in mechanisms of action. These findings indicate that neurophysiological characterization of brain states is particularly informative when evaluating therapeutic mechanisms in conditions involving symptoms that are difficult to assess in rodents such as psychosis, and that mesdopetam should be further explored as a potential novel antipsychotic treatment option for Parkinson psychosis.

Unveiling Assessment Gaps in Parkinson's Disease Psychosis: A Scoping Review.

Parkinson's disease psychosis (PDP) is a multidimensional construct that is challenging to measure. Accurate assessment of PDP requires comprehensive and reliable clinical outcome assessment (COA) measures. To identify PDP measurement gaps in available COAs currently used in clinical and research settings. We conducted a scoping review using Preferred Reporting Items for Systematic Review and Meta-Analysis Extension for Scoping Reviews (PRISMA-ScR) guidelines. We implemented a three-step search strategy in international databases with keywords related to Parkinson's disease (PD), psychosis, and COA. We analyzed studies using COA to assess PDP, classifying their items according to domains and subdomains. From 5673 identified studies, we included 628 containing 432 PDP core items from 32 COAs. Among the 32 COAs, 19 were PD-specific, containing 266 items, constructed as clinician-reported outcomes (ClinRO) (148 items), patient-reported outcomes (PRO) (112 items), and observer-reported outcomes (ObsRO) (six items). Across all PD-specific COAs, regardless of structure, 89.4% of the items from 27 COAs focused primarily on assessing PDP symptoms' severity, and only 9.7% of items probed the impact of PDP on a person's daily functioning. Symptom-based domains are currently prioritized for measuring the severity of PDP, with limited coverage of the functional impact of PDP on patients' lives. Whereas the International Parkinson and Movement Disorder Society has traditionally developed a "Unified" COA that culls items from prior COAs to form a new one, a new COA will largely need newly developed items if the functional impact of PDP is prioritized. © 2024 International Parkinson and Movement Disorder Society.

Parkinson disease psychosis: from phenomenology to neurobiological mechanisms.

Parkinson disease (PD) psychosis (PDP) is a spectrum of illusions, hallucinations and delusions that are associated with PD throughout its disease course. Psychotic phenomena can manifest from the earliest stages of PD and might follow a continuum from minor hallucinations to structured hallucinations and delusions. Initially, PDP was considered to be a complication associated with dopaminergic drug use. However, subsequent research has provided evidence that PDP arises from the progression of brain alterations caused by PD itself, coupled with the use of dopaminergic drugs. The combined dysfunction of attentional control systems, sensory processing, limbic structures, the default mode network and thalamocortical connections provides a conceptual framework to explain how new incoming stimuli are incorrectly categorized, and how aberrant hierarchical predictive processing can produce false percepts that intrude into the stream of consciousness. The past decade has seen the publication of new data on the phenomenology and neurobiological basis of PDP from the initial stages of the disease, as well as the neurotransmitter systems involved in PDP initiation and progression. In this Review, we discuss the latest clinical, neuroimaging and neurochemical evidence that could aid early identification of psychotic phenomena in PD and inform the discovery of new therapeutic targets and strategies.

The effects of treatment with pimavanserin on activities of daily living in patients with Parkinson's disease psychosis: a 16-week, single-arm, open-label study.

More than half of patients with Parkinson's disease will experience psychosis symptoms in the form of hallucinations or delusions at some point over the course of their disease. These symptoms can significantly impact patients' health-related quality of life, cognitive abilities, and activities of daily living (ADLs) and function. Clinical assessment of how psychosis impacts these measures is crucial; however, few studies have assessed this sufficiently, in part due to a lack of appropriate scales for comprehensively assessing function. The objective was to assess how symptoms of Parkinson's disease psychosis (PDP) impact ADLs and function, cognitive function, and health-related quality of life. To address this unmet need, we utilized a modified version of the Functional Status Questionnaire (mFSQ) to measure the impact of psychosis on ADLs and function in patients with PDP treated with pimavanserin, a US Food and Drug Administration-approved medication to treat hallucinations and delusions associated with PDP. Eligible patients entered a 16-week, single-arm, open-label study of oral pimavanserin (34 mg) taken once daily. The primary endpoint was change from baseline to Week 16 on the mFSQ. Secondary endpoints included the Movement Disorders Society-modified Unified Parkinson's Disease Rating Scale (MDS-UPDRS) I and II; Schwab and England ADL; Clinical Global Impression-Severity of Illness (CGI-S), Clinical Global Impression-Improvement (CGI-I), and Patient Global Impression-Improvement (PGI-I), and were also measured as change from baseline to Week 16 using mixed-effects model for repeated measures (MMRM) and least-squares mean (LSM). Our results in a proof-of-concept, 16-week, open-label clinical study in 29 patients demonstrated that an improvement in psychosis symptoms following treatment with pimavanserin was associated with improvements in multiple measures of ADLs and function. Notably, a significant improvement was found on the primary endpoint, change from baseline to Week 16 in mFSQ score [LSM [SE] 14.0 [2.50], n = 17; 95% CI (8.8, 19.3); p < 0.0001]. These findings highlight the potential for improvement in function with improvement of psychosis symptoms in patients with PDP and suggest that the mFSQ may be a measurement tool to evaluate the level of improvement in function. ClinicalTrials.gov Identifier: NCT04292223.

Parkinson’s disease psychosis associated with accelerated multidomain cognitive decline

BackgroundCognitive deficits are associated with poor quality of life and increased risk of development of dementia in patients with Parkinson’s disease (PD) psychosis. The trajectory of cognitive decline in PD...

Functional Brain Networks of Minor and Well-Structured Major Hallucinations in Parkinson's Disease.

Minor hallucinations (mHs) and well-structured major hallucinations (MHs) are common symptoms of Parkinson's disease (PD) psychosis. To investigate the resting-state networks (RSNs) in patients with PD without hallucinations (PD-nH), with mH (PD-mH), and with MH (PD-MH). A total of 73 patients with PD were enrolled (27 PD-nH, 23 PD-mH, and 23 PD-MH). Using seed-based functional connectivity analyses, we investigated the RSNs supposedly related to hallucinations in PD: the default mode network (DMN), executive control network (ECN), dorsal attention network (DAN), ventral attention network (VAN), and visual network (VN). We compared the cognitive function and RSN connectivity among the three groups. In addition, we performed a seed-to-seed analysis to examine the inter-network connectivity within each group using the corresponding RSN seeds. PD-MH group had lower test scores for attention and visuospatial functions compared with those in the other groups. The connectivity of the right intracalcarine cortex within the DAN was lower in the PD-MH group than in the others. The PD-mH and PD-MH groups showed higher connectivity in the left orbitofrontal cortex within DMN compared with the PD-nH group, whereas the connectivity was lower in the right middle frontal gyrus (MFG) within ECN, precuneus cortex within VAN, right middle temporal gyrus and precuneus cortex within DAN, and left MFG within VN. The PD-mH and PD-MH groups showed different inter-network connectivity between the five RSNs, especially regarding DAN connectivity. DAN dysfunction may be a key factor in the progression from mH to MH in patients with PD. © 2023 International Parkinson and Movement Disorder Society.

Risk of long-term care admissions among Medicare beneficiaries treated with pimavanserin or quetiapine for Parkinson's disease psychosis in USA: a retrospective administrative claims database analysis.

Aim: Risk of long-term care (LTC) admission (LTCA) associated with atypical antipsychotic (AAP) use among patients with Parkinson's disease psychosis (PDP) is a major concern. However, no comparative studies have examined the differences in risk of LTC admissions between pimavanserin (PIM), the only FDA-approved AAP for PDP, and other off-label AAPs including quetiapine (QUE). Objective: To examine all-cause LTCA rates and risk among PDP patients treated with AAPs such as QUE or PIM. Methods: Analysis of Parts A, Band D claims (100% Medicare sample; 2013-2019) of Medicare beneficiaries with PDP that initiate ≥12-month continuous PIM or QUE monotherapy from 1 January 2014 to31 December 2018 (i.e., index date) without any AAP use in the 12-month pre-index period was conducted. Outcome assessments among 1:1 propensity score-matched (31 variables - age, sex, race, region and 27 Elixhauser comorbidities) beneficiaries on PIM versus QUE included risk of all-cause skilled nursing facility stays (SNF-stays), LTC-stays, and overall LTCA (i.e., SNF-stays or LTC-stays). All-cause LTCA rates and LTCA risk were compared using logistic regression and cox proportional hazards models, respectively, controlling for demographics, comorbidities and co-existing-dementia or insomnia. Results: Of the matched sample (n=842 for each group) from total sample (n=9652), overall all-cause LTCA and SNF-stay rates were 23.2 and 20.2% for PIM versus 33.8 and 31.4% for QUE, respectively (p<0.05, for each). Hazard ratio (95% CI) for risk of SNF-stay and overall LTCA was 0.78 (0.61, 0.98) and 0.80 (0.66, 0.97), respectively, for PIM versus QUE beneficiaries (p<0.05, for each). Conclusion: The 20% lower risk of LTCA (i.e., greater delay) with PIM versus QUE in this analysis may suggest that PIM should be started early for the treatment of PDP.

Pimavanserin for psychosis in Parkinson's Disease dementia: Subgroup analysis of the HARMONY Trial

IntroductionPimavanserin is FDA-approved to treat Parkinson's disease (PD) psychosis. We analyzed the effect of pimavanserin on psychosis in the PD dementia (PDD) subgroup from the phase 3 HARMONY trial. MethodsThis subgroup analysis included PDD patients enrolled in an international, multicenter, randomized discontinuation study of pimavanserin for dementia-related psychosis. PDD patients with moderate-to-severe psychosis, age 50–90 years, received pimavanserin 34 mg/day for 12 weeks (open-label period). Those with a sustained psychosis response to pimavanserin at weeks 8 and 12 were randomized during the double-blind period to continue pimavanserin or receive placebo. Primary efficacy endpoint was time to psychosis relapse as measured by the SAPS-H + D and CGI-I. Safety was assessed, as were effects on motor symptoms and cognitive abilities using the ESRS-A and MMSE. Results392 patients were enrolled in HARMONY (mean age: 72.6 years; 38.8 % female): 59 had PDD; 49/59 remained on pimavanserin during the open-label period (safety analysis set), and 36/49 were randomized to pimavanserin (n = 16) or placebo (n = 20) in the double-blind phase (intent-to-treat analysis set). Risk of psychosis relapse was lower with pimavanserin 34 mg compared with placebo in the double-blind phase (HR = 0.052; 95 % CI 0.016–0.166; 1-sided nominal p < 0.001). During the open-label period, 46.9 % experienced a treatment-emergent adverse event; event incidence was similar across arms in the double-blind period. Pimavanserin did not adversely affect motor or cognitive function in either treatment phase. ConclusionsPimavanserin significantly reduced risk of psychosis relapse in patients with PDD, was well tolerated, and did not worsen motor or cognitive function.

Incremental health care resource utilization and costs associated among patients with Parkinson's disease psychosis and incident dementia: An analysis of medicare beneficiaries.

Real-world evidence examining the incremental health care resource use (HCRU) and cost burden of incident dementia among patients with Parkinson's disease psychosis (PDP) are needed within the United States (US). To compare HCRU and cost burden between PDP patients with incident dementia (PDP+D) versus without incident dementia (PDP). A retrospective analysis of inpatient (Part A), outpatient (Part B), and prescription drug (Part D) claims from the 100% Medicare sample was conducted to compare PDP+D patients versus PDP patients between 01/01/14-12/31/18. Patients with a diagnosis of dementia, psychosis, secondary parkinsonism, or other psychotic disorders, during 12-month pre-index were excluded. Patients in both groups were matched using 1:1 propensity score matching (PSM) methodology using 31 variables (age, sex, race, region and 27 Elixhauser comorbidity characteristics). Differences in 12-month post-index HCRU rates and mean per patient per year (PPPY) costs for all-cause inpatient (IP) hospitalizations, and by type of IP stay (i.e., short-term [ST-stay], skilled nursing facility [SNF-stay] and long-term [LT-stay]) were analyzed via logistic and gamma log-link regression models. Of the 12,484 patients who met our study criteria, 1855 PSM-matched cohorts were identified. Mean age, gender, and comorbidities were similar in PSM groups. Approximately, 50.3% with PDP+D reported ≥1 all-cause IP hospitalizations versus 36.0% with PDP (p<0.05) during 12-month follow-up. Specifically, all-cause ST-stay, SNF-stay, and LT-stay among PDP+D versus PDP patients were: 45.2% versus 35.7%, 28.3% versus 15.7%, and 8.5% versus 6.0% (p<0.05), respectively. Psychiatric-related ST-stay, SNF-stay, and LT-stay among PDP+D versus PDP patients were: 12.3% versus 9.0%, 7.5% versus 3.4%, and 2.4% versus 1.2% (p<0.05), respectively. Mean PPPY all-cause IP hospitalization costs for PDP+D patients versus PDP patients was $17,891 (±29,882) versus $11,599 (±$25,247) (p<0.05). Patients with PDP+D experience significantly higher all-cause and psychiatric-related IP hospitalizations, including ST-stays, LT stays, and SNF stays. They also had 54% greater mean PPPY IP hospitalization costs versus PDP patients.

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

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. To create and validate the Self-Administered Screening Questionnaire for PD-Associated Psychosis (SASPAP). 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 β-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. 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%. 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.

Brief commentary: Under-recognition of underuse of clozapine in treating psychotic symptoms in Parkinson's disease

Clozapine is an important drug in the treatment of Parkinson's disease (PD). It has proven efficacy in treating PD psychosis without worsening motor function, as well as in treating tremor refractory to L-Dopa, yet it is severely underused in the United States. Unlike the situation of treatment resistant schizophrenia, this underuse is underrecognized.

Unilateral anterior capsulotomy combined with deep brain stimulation for Parkinson's disease psychosis and motor dysfunctions

Psychosis is a frequent and debilitating non-motor symptom of Parkinson's disease (PD). This study aimed to evaluate the availability of unilateral anterior capsulotomy combined with subthalamic nucleus deep brain stimulation (STN-DBS) in managing advanced PD patients comorbid with psychosis. Five advanced PD patients with psychosis who had been treated with unilateral anterior capsulotomy combined with bilateral STN-DBS were assessed. The positive subscore of the Positive and Negative Syndrome Scale (PANSS) and the Unified Parkinson's Disease Rating Scale III (UPDRS-III) were used to assess the efficacy parameter of psychosis and the improved motor symptoms, respectively. The quality of life (QoL) was accessed by an 8-item Parkinson's disease Questionnaire (PDQ-8). Clinical outcome assessments were performed at baseline and follow-ups after one or two years. Significant improvement was observed in PD patients during follow-up after the combined treatment. The positive subscore of PANSS improved by 13.4 (5.7) (mean (SD), p = 0.006). Item P1 (delusions) and Item P3 (hallucinations) of the PANSS improved by 5.0 (0.71) (p < 0.0001) and 3.6 (0.89) (p = 0.0008), respectively. Furthermore, the motor symptoms improved by 32.4 (5.7) (UPDRS-III, p = 0.0002), and the QoL improved by 6.4 (3.8) (PDQ-8, p = 0.021). No significant side effects or complications occurred during the study. For advanced PD patients with refractory psychosis, unilateral anterior capsulotomy combined with bilateral STN-DBS improved PD psychosis and motor dysfunction, providing an effective therapeutic option for such patients.

Pimavanserin treatment increases plasma brain-derived neurotrophic factor levels in rats.

Pimavanserin, a serotonin 5HT-2A receptor inverse agonist is the first-line, FDA-approved treatment of hallucinations and delusions associated with Parkinson's Disease psychosis (PDP), which occurs in up to 50% of PD patients. The neurobiological mechanism underlying the therapeutic effectiveness of Pimavanserin in PDP remains unknown. Several earlier studies have shown that treatment with 5HT-2A antagonists and other drugs acting on the serotonergic system such as SSRIs increase Brain derived neurotrophic factor (BDNF) levels in rodents. BDNF is synthesized as the precursor proBDNF, that undergoes cleavage intra or extracellularly to produce a mature BDNF (mBDNF) protein. mBDNF is believed to play a key role in neuroplasticity and neurogenesis. The present study tested the hypothesis that treatment with Pimavanserin is associated with higher and sustained elevations of mBDNF. Adult Sprague-Dawley male rats were treated with Pimavanserin, Fluoxetine or vehicle for 4 weeks (chronic) or 2 h (acute). BDNF levels were determined by enzyme-linked Immunosorbent assay (ELISA). We found significant increases in plasma mBDNF levels in rats following chronic Pimavanserin treatment, but not in Fluoxetine-treated rats. No significant changes in mBDNF levels were found in the prefrontal cortex or hippocampus following Pimavanserin or Fluoxetine treatment. These findings suggest that increase in mBDNF levels could be a contributing mechanism for the neuroprotective potential of Pimavanserin.

Population Pharmacokinetic Modeling and Stochastic Simulations to Support Pediatric Dose Selection of Pimavanserin.

Pimavanserin is a selective serotonin-modulating agent with inverse agonist/antagonist activity at the 5-hydroxytryptamine2A (5-HT2A ) receptor. The safety and efficacy of pimavanserin 34mg once daily were studied in adults with hallucinations and delusions associated with Parkinson's disease psychosis and other neuropsychiatric conditions. This analysis used model-based simulations of pimavanserin steady-state exposures to identify a dose that generated pediatric exposures comparable with adult exposures achieved with 34mg pimavanserin. A population pharmacokinetics model was developed using pooled plasma drug concentration (ie, actual) data from 13 clinical studies, including a phase1 study of adolescent pediatric patients (aged 13-17years) with various psychiatric conditions. Stochastic simulations were performed to predict exposures in a virtual (ie, simulated) group of pediatric patients (aged 5-17years). Steady-state measures of the area under the plasma concentration-time curve (AUC) and maximum drug concentration (Cmax ) were simulated for relevant age and weight stratifications and compared with simulated exposures in adults (aged 18-49years). The simulated mean AUC ranged from 47.41 to 54.73ng d/mL and the mean Cmax ranged from 41.13 to 50.07ng/mL in adults receiving pimavanserin 34mg. The simulated mean (SD) Cmax of 56.54(24.58)ng/mL with pimavanserin 34mg in patients aged 10-17years was similar to that in adults. Pimavanserin 20mg yielded a mean (SD) Cmax of 45.30(21.31)ng/mL in patients aged 5-9years and 49.18(22.91)ng/mL in the pediatric patient weight group of 14-25kg, which are values close to the Cmax in adults treated with 34mg. Pimavanserin 20 and 34mg in pediatric patients aged 5-9 and 10-17years, respectively, yielded exposures similar to daily pimavanserin 34mg in adults aged 18-49years.

Minor Phenomena in Parkinson's Disease-Prevalence, Associations, and Risk of Developing Psychosis.

Minor phenomena, including passage phenomena, feeling of presence, and illusions, are common and may represent a prodromal form of psychosis in Parkinson's disease (PD). We examined the prevalence and clinical correlates of minor phenomena, and their potential role as a risk factor for PD psychosis. A novel questionnaire, the Psychosis and Mild Perceptual Disturbances Questionnaire for PD (PMPDQ), was completed by Fox Insight cohort participants with and without PD. Additional assessments included the Non-Motor Symptoms Questionnaire (NMSQuest), REM Sleep Behavior Disorder Single Question Screen (RBD1Q), Movement Disorder Society-Unified Parkinson Disease Rating Scale Part II, demographic features, and medication usage. For participants with PD, we used regression models to identify clinical associations and predictors of incident psychosis over one year of follow-up. Among participants with PD (n = 5950) and without PD (n = 1879), the prevalence of minor phenomena was 43.1% and 31.7% (P < .001). Of the 3760 participants with PD and no baseline psychosis, independent correlates of minor phenomena included positive responses on the NMSQuest apathy/attention/memory (OR 1.7, 95% CI 1.3-2.1, P < .001) or sexual function domain (OR 1.3, 95% CI 1.1-1.6, P = .01) and positive RBD1Q (OR 1.3, 95% CI 1.05-1.5, P = .01). Independent risk factors for incident PD psychosis included the presence of minor phenomena (HR 3.0, 95% CI 2.4-3.9, P < .001), positive response on the NMSQuest apathy/attention/memory domain (HR 1.8, 95% CI 1.3-2.6, P < .001), and positive RBD1Q (HR 1.5, 95% CI 1.1-1.9, P = .004). Minor phenomena are common, associated with specific non-motor symptoms, and an independent predictor of incident psychosis in PD.

Letter to the Editors: A Consideration for the Study of the Use of Cyproheptadine in Parkinson Disease Psychosis.

Letter to the Editors: A Consideration for the Study of the Use of Cyproheptadine in Parkinson Disease Psychosis.

Effect of the mGlu4 positive allosteric modulator ADX-88178 on parkinsonism, psychosis-like behaviours and dyskinesia in the MPTP-lesioned marmoset.

Positive allosteric modulation of metabotropic glutamate type 4 (mGlu4) receptors is a promising strategy to alleviate parkinsonian disability and L-3,4-dihydroxyphenylalanine (L-DOPA) induced dyskinesia. ADX-88178 is a highly selective mGlu4 positive allosteric modulator (PAM) that previously enhanced the anti-parkinsonian action of L-DOPA in the 6-hydroxydopamine-lesioned rat model of Parkinson's disease (PD). We sought to explore the effects of ADX-88178 on psychosis-like behaviours (PLBs) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. We also aimed to determine the effect of ADX-88178 on parkinsonism and dyskinesia. Six MPTP-lesioned marmosets were administered L-DOPA chronically to induce stable PLBs and dyskinesias. They were then administered ADX-88178 (0.01, 0.1 and 1mg/kg) or vehicle, in combination with L-DOPA/benserazide (15/3.75mg/kg), both sub-cutaneously, in a randomised fashion. PLBs, parkinsonism and dyskinesia were then measured. ADX-88178 mildly worsened global PLBs at the dose of 1mg/kg (by 13%, P = 0.020). L-DOPA alone conferred 158min of on-time, while the duration of on-time was 212min (34% increase, P = 0.011), after adding ADX-88178 1mg/kg to L-DOPA. Accordingly, ADX-88178 1mg/kg reduced global parkinsonian disability, by 38% (P = 0.0096). ADX-88178 1mg/kg diminished peak dose dyskinesia by 34% (P = 0.015). Minimal effects were provided by lower doses. Whereas these results provide additional evidence of the anti-parkinsonian and anti-dyskinetic effects of mGlu4 positive allosteric modulation as an adjunct to L-DOPA, they also suggest that ADX-88178 may exacerbate dopaminergic psychosis. Further studies are needed to evaluate this possible adverse effect of mGlu4 PAMs on PD psychosis.

Psychosis in Parkinson’s Disease and Current Management Trends- an Updated Review of Literature

As a neurodegenerative disorder, Parkinson’s disease (PD) is characterized by a combination of premotor, motor, and nonmotor symptoms. PD is commonly accompanied by psychosis, which is one of the commonest symptoms in the long run. As a result of Parkinson’s disease psychosis (PDP), symptoms can range from minor consequences of the disease (illusions, passage hallucinations, and presence hallucinations), to visual and nonvisual hallucinations and delusions. PDP is associated with a reduction in function and a reduction in quality of life as well. It is commonly believed that PDP is related to economic burden, and it has a significant impact on the utilization of long-term care services. The main focus should be on diagnosing, classifying, and managing PDP in an appropriate manner. As a first step in the management of PDP patients, the emphasis should be on identifying and treating any contributing medical factors, reducing or discontinuing medications that could cause or worsen psychosis, as well as nonpharmacological strategies and considering acetylcholinesterase inhibitors for treatment when dementia is present. A number of medications are being considered for use in PDP, including pimavanserin, quetiapine, and clozapine. The purpose of the current review is to provide a comprehensive understanding of the disorder in the general population with PD, including epidemiology, psychotic symptoms, risk factors, triggers, neuro-signaling pathways, diagnosis, and treatment of PDP.