The psychosis spectrum in Parkinson disease

Reduction in presynaptic dopamine transporter may be associated with future problematic delusion

OBJECTIVES

Psychosis, especially in delusions, greatly impairs the quality of life of patients with Parkinson's disease (PD) and their caregivers. Few objective risk indicators of the association between psychosis and clinical features has been reported. It is unclear whether the reduction in DAT binding represents the underlying mechanism of delusion or its association. There are no long-term data on the objective prognostic value of DAT binding for delusions. We investigated whether DAT binding at baseline can be a prognostic risk factor for future development of PD delusions.

MATERIALS AND METHODS

We reviewed the detailed clinical chart of patients with PD without a history of psychosis who underwent [123I]FP-CIT SPECT during the disease. The endpoint was defined as when the delusions occurred during the 5 years after the examination of [123I]FP-CIT SPECT. Specific binding ratio (SBR) values were calculated.

RESULTS

Sixty-one patients with PD were included in the analysis, and 11 patients had delusions within 5 years of [123I] FP-CIT SPECT. The average (p = 0.004), minimum (p = 0.004), maximum (p = 0.001), right-sided (p = 0.002), and left-sided (p = 0.003) SBRs in the striatum were significantly smaller in patients with delusions than in patients without delusions. Each difference of each SBR was significantly smaller than those without delusions after adjusting after controlling for age, gender, disease severity, timing of [123I]FP-CIT SPECT, anti-parkinsonian medications, hospitalization, administering more or newly anti-parkinsonian drugs, and receiving DBS or LCIG.

CONCLUSIONS

PD delusions is still problematic, and lowering DAT binding may be helpful for predicting future delusions, regardless of the timing of [123I]FP-CIT SPECT.

Distinct grey and white matter changes are associated with the phenomenology of visual hallucinations in Lewy Body Disease

Visual hallucinations in Lewy body disease (LBD) can be differentiated based on phenomenology into minor phenomena (MVH) and complex hallucinations (CVH). MVH include a variety of phenomena, such as illusions, presence and passage hallucinations occurring at early stages of LBD. The neural mechanisms of visual hallucinations are largely unknown. The hodotopic model posits that the hallucination state is due to abnormal activity in specialized visual areas, that occurs in the context of wider network connectivity alterations and that phenomenology of VH, including content and temporal characteristics, may help identify brain regions underpinning these phenomena. Here we investigated both the topological and hodological neural basis of visual hallucinations integrating grey and white matter imaging analyses. We studied LBD patients with VH and age matched healthy controls (HC). VH were assessed using a North-East-Visual-Hallucinations-Interview that captures phenomenological detail. Then we applied voxel-based morphometry and tract based spatial statistics approaches to identify grey and white matter changes. First, we compared LBD patients and HC. We found a reduced grey matter volume and a widespread damage of white tracts in LBD compared to HC. Then we tested the association between CVH and MVH and grey and white matter indices. We found that CVH duration was associated with decreased grey matter volume in the fusiform gyrus suggesting that LBD neurodegeneration-related abnormal activity in this area is responsible for CVH. An unexpected finding was that MVH severity was associated with a greater integrity of white matter tracts, specifically those connecting dorsal, ventral attention networks and visual areas. Our results suggest that networks underlying MVH need to be partly intact and functional for MVH experiences to occur, while CVH occur when cortical areas are damaged. The findings support the hodotopic view and the hypothesis that MVH and CVH relate to different neural mechanisms, with wider implications for the treatment of these symptoms in a clinical context.

Progress in Pharmacologic Management of Neuropsychiatric Syndromes in Neurodegenerative Disorders: A Review

Importance

Neuropsychiatric syndromes (NPSs) are common in neurodegenerative disorders (NDDs); compromise the quality of life of patients and their care partners; and are associated with faster disease progression, earlier need for nursing home care, and poorer quality of life. Advances in translational pharmacology, clinical trial design and conduct, and understanding of the pathobiology of NDDs are bringing new therapies to clinical care.

Observations

Consensus definitions have evolved for psychosis, agitation, apathy, depression, and disinhibition in NDDs. Psychosocial interventions may reduce mild behavioral symptoms in patients with NDD, and pharmacotherapy is available for NPSs in NDDs. Brexpiprazole is approved for treatment of agitation associated with Alzheimer disease dementia, and pimavanserin is approved for treatment of delusions and hallucinations associated with psychosis of Parkinson disease. Trials are being conducted across several of the NDDs, and a variety of mechanisms of action are being assessed for their effect on NPSs.

Conclusions and Relevance

Detection and characterization of NPSs in patients with NDDs is the foundation for excellent care. New definitions for NPSs in NDDs may inform choices regarding clinical trial populations and translate into clinical practice. Psychosocial and pharmacologic therapies may reduce behavioral symptoms and improve quality of life for patients and caregivers. Approved agents may establish regulatory precedents, demonstrate successful trial strategies, and provide the foundation for further advances in treatment development.

On the Optimal Diagnosis and the Evolving Role of Pimavanserin in Parkinson's Disease Psychosis

Parkinson's disease (PD) is associated with the development of psychosis (PDP), including hallucinations and delusions, in more than half of the patient population. Optimal PD management must therefore involve considerations about both motor and non-motor symptoms. Often, clinicians fail to diagnosis psychosis in patients with PD and, when it is recognized, treat it suboptimally, despite the availability of multiple interventions. In this paper, we provide a summary of the current guidelines and clinical evidence for treating PDP with antipsychotics. We also provide recommendations for diagnosis and follow-up. Finally, an updated treatment algorithm for PDP that incorporates the use of pimavanserin, the only US FDA-approved drug for the treatment of PDP, was developed by extrapolating from a limited evidence base to bridge to clinical practice using expert opinion and experience. Because pimavanserin is only approved for the treatment of PDP in the US, in other parts of the world other recommendations and algorithms must be considered.

Integration of neuroscience into psychiatric training and practice: suggestions for implementation

Mainstream psychiatric practice requires a solid grounding in neuroscience, an important part of the biopsychosocial model, allowing for holistic person-centred care. There have been repeated calls for better integration of neuroscience into training, although so far with less focus on implementation for life-long learning. We suggest that such training should be accessible and utilised by all psychiatrists, not solely those with a special interest in neuropsychiatry. By considering recent positive developments within the general psychiatry curricula and neuropsychiatric resource implementation, we propose strategies for how this can be progressed, minimising regional disparities within the growing world of virtual learning.

Exploring the Spectrum of Visual Illusions and Other Minor Hallucinations in Patients with Parkinson's Disease in Lithuania

Background and Objectives: Parkinson's disease (PD) is associated with various non-motor symptoms, including minor hallucinations, comprising visual illusions and presence and passage hallucinations. Despite their occurrence, even in newly diagnosed PD patients, data regarding the prevalence and characteristics of minor hallucinations, visual illusions in particular, remain limited. The aim of this study was to address this knowledge gap by assessing the prevalence of minor hallucinations in PD patients, with a focus on visual illusions. Materials and Methods: In this prospective pilot study, we enrolled 35 PD patients without dementia and 35 age- and gender-matched PD-unaffected individuals. Cognitive function was assessed using the Montreal Cognitive Assessment, clinical data were collected, and all subjects were assessed via questionnaires regarding 20 types of visual illusions and other minor hallucinations. Results: The prevalence of minor hallucinations was significantly higher among PD patients compared to controls (45.7% vs. 11.4%, p = 0.003). PD patients reported visual illusions and presence hallucinations more frequently than the controls (37.1% vs. 8.6% and 22.9% vs. 2.9%, p = 0.009 and p = 0.028, respectively), with no significant difference in passage hallucinations (20% vs. 8.6%, p = 0.306). In the PD group, the most frequently observed visual illusions were complex visual illusions, kinetopsia, and pelopsia; the latter was also the most common visual illusion in the control group. PD patients experiencing visual illusions were more likely to report presence hallucinations compared to patients without visual illusions (53.8% vs. 4.5%, p = 0.002); no significant differences in other clinical characteristics were found. Conclusions: Minor hallucinations are a common phenomenon among PD patients without dementia, with a higher prevalence than among healthy controls. Visual illusions are the most prevalent type of minor hallucinations, affecting more than a third of PD patients, with complex visual illusions, kinetopsia, and pelopsia being the most frequently reported types.

Alterations of Cortical Structure and Neurophysiology in Parkinson's Disease Are Aligned with Neurochemical Systems

OBJECTIVE

Parkinson's disease (PD) affects the structural integrity and neurophysiological signaling of the cortex. These alterations are related to the motor and cognitive symptoms of the disease. How these changes are related to the neurochemical systems of the cortex is unknown.

METHODS

We used T1-weighted magnetic resonance imaging (MRI) and magnetoencephalography (MEG) to measure cortical thickness and task-free neurophysiological activity in patients with idiopathic PD (nMEG = 79, nMRI = 65) and matched healthy controls (nMEG = 65, nMRI = 37). Using linear mixed-effects models, we examined the topographical alignment of cortical structural and neurophysiological alterations in PD with cortical atlases of 19 neurotransmitter receptor and transporter densities.

RESULTS

We found that neurophysiological alterations in PD occur primarily in brain regions rich in acetylcholinergic, serotonergic, and glutamatergic systems, with protective implications for cognitive and psychiatric symptoms. In contrast, cortical thinning occurs preferentially in regions rich in noradrenergic systems, and the strength of this alignment relates to motor deficits.

INTERPRETATION

This study shows that the spatial organization of neurophysiological and structural alterations in PD is relevant for nonmotor and motor impairments. The data also advance the identification of the neurochemical systems implicated. The approach uses novel nested atlas modeling methodology that is transferrable to research in other neurological and neuropsychiatric diseases and syndromes. ANN NEUROL 2024;95:802-816.

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.

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

BACKGROUND

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.

OBJECTIVE

To identify PDP measurement gaps in available COAs currently used in clinical and research settings.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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

AIMS

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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?

Objective

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).

Methods

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.

Results

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.

Conclusion

PD-P is probably associated with overrepresentation of T-allele of HOMER1 rs4704560, and larger studies are warranted to confirm our results.

Parkinson's disease and schizophrenia interactomes contain temporally distinct gene clusters underlying comorbid mechanisms and unique disease processes

Genome-wide association studies suggest significant overlaps in Parkinson's disease (PD) and schizophrenia (SZ) risks, but the underlying mechanisms remain elusive. The protein-protein interaction network ('interactome') plays a crucial role in PD and SZ and can incorporate their spatiotemporal specificities. Therefore, to study the linked biology of PD and SZ, we compiled PD- and SZ-associated genes from the DisGeNET database, and constructed their interactomes using BioGRID and HPRD. We examined the interactomes using clustering and enrichment analyses, in conjunction with the transcriptomic data of 26 brain regions spanning foetal stages to adulthood available in the BrainSpan Atlas. PD and SZ interactomes formed four gene clusters with distinct temporal identities (Disease Gene Networks or 'DGNs'1-4). DGN1 had unique SZ interactome genes highly expressed across developmental stages, corresponding to a neurodevelopmental SZ subtype. DGN2, containing unique SZ interactome genes expressed from early infancy to adulthood, correlated with an inflammation-driven SZ subtype and adult SZ risk. DGN3 contained unique PD interactome genes expressed in late infancy, early and late childhood, and adulthood, and involved in mitochondrial pathways. DGN4, containing prenatally-expressed genes common to both the interactomes, involved in stem cell pluripotency and overlapping with the interactome of 22q11 deletion syndrome (comorbid psychosis and Parkinsonism), potentially regulates neurodevelopmental mechanisms in PD-SZ comorbidity. Our findings suggest that disrupted neurodevelopment (regulated by DGN4) could expose risk windows in PD and SZ, later elevating disease risk through inflammation (DGN2). Alternatively, variant clustering in DGNs may produce disease subtypes, e.g., PD-SZ comorbidity with DGN4, and early/late-onset SZ with DGN1/DGN2.

Cognitive and executive impairments in Parkinson's disease psychosis: a Bayesian meta-analysis

BACKGROUND

Cognitive and executive deficits lead to worsening of quality of life and are a risk factor for developing dementia in people with Parkinson's disease (PD) with psychosis (PDP). However, which key cognitive domains are differentially affected in PDP compared with those without (PDnP), remains unclear. Here, we examined this using a Bayesian meta-analytical approach.

METHODS

Searches were conducted on PubMed, Web of Science, SCOPUS, Medline and PsycINFO. Hedges' g effect-size estimates were extracted from eligible studies as a measure of standard mean differences between PDP and PDnP participants. Meta-analyses were conducted separately for each cognitive domain and subdomain, we examined the effect of age, PD medications, PD duration and severity, depression and psychosis severity for all major domains with meta-regressions.

RESULTS

Effect-size estimates suggest worse performance on all major domains (k=105 studies) in PDP compared with PDnP participants, with global cognition (k=103 studies, g=-0.57), processing speed (k=29 studies, g=-0.58), executive functions (k=33, g=-0.56), episodic memory (k=30 studies, g=-0.58) and perception (k=34 studies, g=-0.55) as the most likely affected domains. Age, depression and PD duration had moderating effects on task-related performance across most of the major nine domains.

CONCLUSIONS

We report extensive deficits across nine domains as well as subdomains in PD psychosis, with global cognition, processing speed and executive functions as the most likely impaired. The presence of depression may influence task-related performance in PDP, alongside age and PD duration, but not dose of dopamine replacement treatments.

A Comprehensive Review of the Role of Biomarkers in Early Diagnosis of Parkinson's Disease

Parkinson's disease (PD) is a complex neurological, degenerative clinical condition depicted by the advancing loss of dopaminergic neurons in the substantia nigra pars compacta, which manifests itself as a myriad of sensorimotor and non-motor signs in patients. The disease occurs due to the reduced levels of the neurotransmitter dopamine in the brain, which is primarily associated with functional characteristics regarding mobility and cognition. The basal ganglion is mainly involved in the generation of cognitive functions and therefore is the most significantly associated area in PD. Since the classical diagnosis and assessment of PD depends majorly on the appearance of motor characteristics, which only arise when ~60-80% of the dopamine neuronal cell death has already occurred, it is imperative we focus on identifying biomarkers that can help us assess and diagnose PD in the earlier stages of disease progression, thus providing a better prognosis for the patients. This review article will focus on the different biomarkers that are currently available and in use, divided under the headings of clinical, biological, imaging, and genetic biomarkers, and assess their specificity and sensitivity toward providing an early assessment of Parkinson's for the patients and the future of preclinical diagnostics using molecular biomarkers. PD affects over 1% of the population worldwide and only ranks second to Alzheimer's disease in the context of its incidence and consequent socioeconomic burden. While recent breakthroughs in biomarkers have dramatically improved patients' odds of survival and prognosis, it still remains primarily a symptomatic diagnostic tool. It is an area of research that requires to focus on creating more advanced approaches toward diagnosing PD early, involving clinical diagnostics, neuroimaging technology, and molecular biology collaborations to provide the highest degree of care and quality of life that a Parkinson's patient deserves.

Semantic dementia: a complex and culturally influenced presentation

SUMMARY

The variants of frontotemporal dementia (FTD) require careful differentiation from primary psychiatric disorders as the neuropsychiatric manifestations can overshadow the unique cognitive deficits. The language variants of FTD are less readily recognised by trainees despite making up around 43% of cases. This educational article presents an anonymised case of one of the language variants: semantic dementia. The cognitive deficits and neuropsychiatric manifestations (delusions and hyperreligiosity) are explored in terms of aetiology and management. By the end of the article, readers should be able to differentiate FTD from Alzheimer's disease, understand the principles of management and associated risks, and develop a multifaceted approach to hyperreligiosity in dementia.

Abnormal higher-order network interactions in Parkinson's disease visual hallucinations

Visual hallucinations in Parkinson's disease can be viewed from a systems-level perspective, whereby dysfunctional communication between brain networks responsible for perception predisposes a person to hallucinate. To this end, abnormal functional interactions between higher-order and primary sensory networks have been implicated in the pathophysiology of visual hallucinations in Parkinson's disease, however the precise signatures remain to be determined. Dimensionality reduction techniques offer a novel means for simplifying the interpretation of multidimensional brain imaging data, identifying hierarchical patterns in the data that are driven by both within- and between-functional network changes. Here, we applied two complementary non-linear dimensionality reduction techniques-diffusion-map embedding and t-distributed stochastic neighbour embedding (t-SNE)-to resting state functional MRI data, in order to characterize the altered functional hierarchy associated with susceptibility to visual hallucinations. Our study involved 77 people with Parkinson's disease (31 with hallucinations; 46 without hallucinations) and 19 age-matched healthy control subjects. In patients with visual hallucinations, we found compression of the unimodal-heteromodal gradient consistent with increased functional integration between sensory and higher order networks. This was mirrored in a traditional functional connectivity analysis, which showed increased connectivity between the visual and default mode networks in the hallucinating group. Together, these results suggest a route by which higher-order regions may have excessive influence over earlier sensory processes, as proposed by theoretical models of hallucinations across disorders. By contrast, the t-SNE analysis identified distinct alterations in prefrontal regions, suggesting an additional layer of complexity in the functional brain network abnormalities implicated in hallucinations, which was not apparent in traditional functional connectivity analyses. Together, the results confirm abnormal brain organization associated with the hallucinating phenotype in Parkinson's disease and highlight the utility of applying convergent dimensionality reduction techniques to investigate complex clinical symptoms. In addition, the patterns we describe in Parkinson's disease converge with those seen in other conditions, suggesting that reduced hierarchical differentiation across sensory-perceptual systems may be a common transdiagnostic vulnerability in neuropsychiatric disorders with perceptual disturbances.

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

BACKGROUND

Minor hallucinations (mHs) and well-structured major hallucinations (MHs) are common symptoms of Parkinson's disease (PD) psychosis.

OBJECTIVES

To investigate the resting-state networks (RSNs) in patients with PD without hallucinations (PD-nH), with mH (PD-mH), and with MH (PD-MH).

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

A general clinical overview of the non-motor symptoms in Parkinson's disease: Neuropsychiatric symptoms

The heterogeneity of non-motor features observed in people with Parkinson's disease (PD) is often dominated by one or more symptoms belonging to the neuropsychiatric spectrum, such as cognitive impairment, psychosis, depression, anxiety, and apathy. Due to their high prevalence in people with PD (PwP) and their occurrence in every stage of the disease, from the prodromal to the advanced stage, it is not surprising that PD can be conceptualised as a complex neuropsychiatric disorder. Despite progress in understanding the pathophysiological mechanisms underlying the neuropsychiatric signs and symptoms in PD, and better identification and diagnosis of these symptoms, effective treatments are still a major unmet need. The impact of these symptoms on the quality of life of PwP and caregivers, as well as their contribution to the overall non-motor symptom burden can be greater than that of motor symptoms and require a personalised, holistic approach. In this chapter, we provide a general clinical overview of the major neuropsychiatric symptoms of PD.

Overview of late-onset psychoses

BACKGROUND

Several etiologies can underlie the development of late-onset psychosis, defined by first psychotic episode after age 40 years. Late-onset psychosis is distressing to patients and caregivers, often difficult to diagnose and treat effectively, and associated with increased morbidity and mortality.

METHODS

The literature was reviewed with searches in Pubmed, MEDLINE, and the Cochrane library. Search terms included "psychosis," "delusions," hallucinations," "late onset," "secondary psychoses," "schizophrenia," bipolar disorder," "psychotic depression," "delirium," "dementia," "Alzheimer's," "Lewy body," "Parkinson's, "vascular dementia," and "frontotemporal dementia." This overview covers the epidemiology, clinical features, neurobiology, and therapeutics of late-onset psychoses.

RESULTS

Late-onset schizophrenia, delusional disorder, and psychotic depression have unique clinical characteristics. The presentation of late-onset psychosis requires investigation for underlying etiologies of "secondary" psychosis, which include neurodegenerative, metabolic, infectious, inflammatory, nutritional, endocrine, and medication toxicity. In delirium, psychosis is common but controlled evidence is lacking to support psychotropic medication use. Delusions and hallucinations are common in Alzheimer's disease, and hallucinations are common in Parkinson's disease and Lewy body dementia. Psychosis in dementia is associated with increased agitation and a poor prognosis. Although commonly used, no medications are currently approved for treating psychosis in dementia patients in the USA and nonpharmacological interventions need consideration.

CONCLUSION

The plethora of possible causes of late-onset psychosis requires accurate diagnosis, estimation of prognosis, and cautious clinical management because older adults have greater susceptibility to the adverse effects of psychotropic medications, particularly antipsychotics. Research is warranted on developing and testing efficacious and safe treatments for late-onset psychotic disorders.

The central role of the Thalamus in psychosis, lessons from neurodegenerative diseases and psychedelics

The PD-DLB psychosis complex found in Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB) includes hallucinations, Somatic Symptom/Functional Disorders, and delusions. These disorders exhibit similar presentation patterns and progression. Mechanisms at the root of these symptoms also share similarities with processes promoting altered states of consciousness found in Rapid Eye Movement sleep, psychiatric disorders, or the intake of psychedelic compounds. We propose that these mechanisms find a crucial driver and trigger in the dysregulated activity of high-order thalamic nuclei set in motion by ThalamoCortical Dysrhythmia (TCD). TCD generates the loss of finely tuned cortico-cortical modulations promoted by the thalamus and unleashes the aberrant activity of the Default Mode Network (DMN). TCD moves in parallel with altered thalamic filtering of external and internal information. The process produces an input overload to the cortex, thereby exacerbating DMN decoupling from task-positive networks. These phenomena alter the brain metastability, creating dreamlike, dissociative, or altered states of consciousness. In support of this hypothesis, mind-altering psychedelic drugs also modulate thalamic-cortical pathways. Understanding the pathophysiological background of these conditions provides a conceptual bridge between neurology and psychiatry, thereby helping to generate a promising and converging area of investigation and therapeutic efforts.

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 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.

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.

The shared genetic risk architecture of neurological and psychiatric disorders: a genome-wide analysis

While neurological and psychiatric disorders have historically been considered to reflect distinct pathogenic entities, recent findings suggest shared pathobiological mechanisms. However, the extent to which these heritable disorders share genetic influences remains unclear. Here, we performed a comprehensive analysis of GWAS data, involving nearly 1 million cases across ten neurological diseases and ten psychiatric disorders, to compare their common genetic risk and biological underpinnings. Using complementary statistical tools, we demonstrate widespread genetic overlap across the disorders, even in the absence of genetic correlations. This indicates that a large set of common variants impact risk of multiple neurological and psychiatric disorders, but with divergent effect sizes. Furthermore, biological interrogation revealed a range of biological processes associated with neurological diseases, while psychiatric disorders consistently implicated neuronal biology. Altogether, the study indicates that neurological and psychiatric disorders share key etiological aspects, which has important implications for disease classification, precision medicine, and clinical practice.

Association of Neuropsychiatric Symptom Profiles With Cognitive Decline in Patients With Parkinson Disease and Mild Cognitive Impairment

BACKGROUND AND OBJECTIVES

Neuropsychiatric symptoms (NPS) are closely associated with cognitive decline in patients with Parkinson disease (PD). We investigated which profiles of NPS are associated with the risk of dementia in PD with mild cognitive impairment (PD-MCI).

METHODS

We retrospectively assessed 338 patients with PD-MCI from a single tertiary hospital, who underwent neuropsychological tests and a neuropsychiatric inventory (NPI) questionnaire. We conducted a factor analysis of the dichotomized presence of 12 NPI symptoms, yielding 3 NPI factors: factor 1, mood symptoms; factor 2, hyperactivity-related symptoms; and factor 3, psychotic symptoms. Factor analysis of the severity of NPI symptoms also identified similar NPI factors. The neuropsychiatric correlates of NPI factors were evaluated using general linear models for cognitive tests. Subsequently, we evaluated the hazard ratio (HR) of NPI factors on conversion to dementia.

RESULTS

A higher prevalence factor 1 score was associated with lower scores in the verbal memory (β = -0.15; 95% CI -0.24 to -0.06; p = 0.001) and executive domains (β = -0.16; 95% CI -0.28 to -0.04; p = 0.007), whereas higher severity factor 2 scores were associated with lower scores in the naming (β = -0.16; 95% CI -0.28 to -0.03; p = 0.012), visuospatial (β = -0.24; 95% CI -0.41 to -0.07; p = 0.005), and verbal memory domains (β = -0.15; 95% CI -0.24 to -0.05; p = 0.005). A higher severity factor 3 score was associated with lower scores in the visuospatial domain (β = -0.25; 95% CI -0.46 to -0.07; p = 0.007). Cox regression models demonstrated that the risk of dementia was increased in those with higher prevalence factor 1 (HR = 1.48, 95% CI 1.17-1.88, p = 0.001) and factor 2 scores (HR = 1.27, 95% CI 1.07-1.51, p = 0.007) and severity factor 3 score (HR = 1.52, 95% CI 1.29-1.80, p < 0.001) after adjusting for age, sex, education, disease duration, scores for cognition and parkinsonism, and levodopa equivalent dose.

DISCUSSION

This study demonstrated that a higher burden of NPS is associated with dementia conversion in patients with PD-MCI.

Minor hallucinations in Parkinson's disease with probable rapid eye movement sleep behavior disorder

Background

Rapid eye movement sleep behavior disorder (RBD) and minor hallucinations (MHs) are prevalent nonmotor symptoms in Parkinson's disease (PD). The purpose of this study was to explore the association of MHs in PD patients with probable RBD (pRBD).

Methods

This cross-sectional study included 291 patients diagnosed with PD. Patients who scored 6 or higher on the Rapid Eye Movement Behavior Disorder (RBD) Screening Questionnaire were defined as pRBD. A comprehensive evaluation was performed for all patients, including the collection of demographic information, clinical assessment, and MH features.

Results

Among the 291 PD patients, 69 (23.7%) had pRBD. MHs were observed in 35 (50.7%) patients with pRBD, significantly higher than 29.7% in patients without RBD (p = 0.015). The main type of MHs in pRBD was presence hallucinations with variable content. Patients with pRBD and MHs tended to be older, had a longer disease duration, and were more likely to take levodopa or dopamine-receptor agonists. Besides, the pRBD with MHs group had higher scores on the Nonmotor Symptoms Questionnaire (NMS-Quest) and Hamilton Anxiety Scale (HAMA). Binary logistic regression analysis revealed that longer disease duration and higher NMS-Quest scores were associated with MHs in PD patients with pRBD.

Conclusion

A high prevalence of MHs was observed in PD patients with pRBD. The main type of MHs in pRBD was presence hallucinations. MHs in PD with RBD are mainly associated with disease duration and severity of nonmotor symptoms. These findings provide new insights into the interaction between MHs and RBD.

Ulotaront, a Trace Amine-Associated Receptor 1/Serotonin 5-HT1A Agonist, in Patients With Parkinson Disease Psychosis: A Pilot Study

Background and Objectives

Ulotaront (SEP-363856) is a trace amine-associated receptor 1 agonist with 5-HT_1A receptor agonist activity currently in phase 3 clinical development for the treatment of schizophrenia. In this exploratory, flexibly dosed study, ulotaront was evaluated for the treatment of Parkinson disease psychosis (PDP).

Methods

Patients with PDP requiring antipsychotic therapy were randomized, double-blind to ulotaront (25, 50, or 75 mg/d) or placebo. Mixed Model for Repeated Measures was used to assess change from baseline in the Scale for the Assessment of Positive Symptoms for Parkinson Disease (SAPS-PD) at 6 weeks (primary end point).

Results

The efficacy analysis sample comprised 38 patients (ulotaront, n = 24; placebo, n = 14). SAPS-PD total scores were numerically reduced in ulotaront-treated vs placebo-treated patients from week 1 to week 6: Least squares mean (95% confidence interval) difference in change from baseline at week 6 was -1.1 (-6.5, 4.3, p = 0.681). PDP symptom complete remission (≥100% improvement [reduction] from baseline in SAPS-PD total score) was observed in 25% of ulotaront-treated vs 0% of placebo-treated patients. SAPS-PD and Neuropsychiatric Inventory hallucinations subscales were numerically reduced vs placebo, and SAPS-PD total scores were reduced in patients with greater cognitive impairment (baseline Mini-Mental State Examination [MMSE] scores ≤24). Ulotaront improved Scales for Outcomes in Parkinson Disease Sleep Scale - Daytime Sleepiness scores (p = 0.022). There was no worsening of Unified Parkinson Disease Rating Scale Part III motor score, MMSE, or vital signs. Adverse events (≥10%) with ulotaront vs placebo included hallucinations (24% vs 14%), confusional state (20% vs 14%), dizziness (16% vs 7%), nausea (12% vs 7%), and falls (12% vs 21%).

Discussion

In this exploratory pilot study, ulotaront may decrease PDP symptoms without worsening motor function, particularly in patients with cognitive impairment.

Trial Registration Information

ClinicalTrials.gov identifier: NCT02969369; submitted: November 17, 2016; study start date: December 31, 2016.

Classification of Evidence

This Class II study was an exploratory pilot study that was underpowered to detect a statistically significant difference between ulotaront and placebo in the treatment of patients with Parkinson disease psychosis without worsening motor function.

A multicentre study on grey matter morphometric biomarkers for classifying early schizophrenia and parkinson's disease psychosis

Psychotic symptoms occur in a majority of schizophrenia patients and in ~50% of all Parkinson's disease (PD) patients. Altered grey matter (GM) structure within several brain areas and networks may contribute to their pathogenesis. Little is known, however, about transdiagnostic similarities when psychotic symptoms occur in different disorders, such as in schizophrenia and PD. The present study investigated a large, multicenter sample containing 722 participants: 146 patients with first episode psychosis, FEP; 106 individuals in at-risk mental state for developing psychosis, ARMS; 145 healthy controls matching FEP and ARMS, Con-Psy; 92 PD patients with psychotic symptoms, PDP; 145 PD patients without psychotic symptoms, PDN; 88 healthy controls matching PDN and PDP, Con-PD. We applied source-based morphometry in association with receiver operating curves (ROC) analyses to identify common GM structural covariance networks (SCN) and investigated their accuracy in identifying the different patient groups. We assessed group-specific homogeneity and variability across the different networks and potential associations with clinical symptoms. SCN-extracted GM values differed significantly between FEP and Con-Psy, PDP and Con-PD, PDN and Con-PD, as well as PDN and PDP, indicating significant overall grey matter reductions in PD and early schizophrenia. ROC analyses showed that SCN-based classification algorithms allow good classification (AUC ~0.80) of FEP and Con-Psy, and fair performance (AUC ~0.72) when differentiating PDP from Con-PD. Importantly, the best performance was found in partly the same networks, including the thalamus. Alterations within selected SCNs may be related to the presence of psychotic symptoms in both early schizophrenia and PD psychosis, indicating some commonality of underlying mechanisms. Furthermore, results provide evidence that GM volume within specific SCNs may serve as a biomarker for identifying FEP and PDP.

Structural and neurophysiological alterations in Parkinson's disease are aligned with cortical neurochemical systems

Parkinson's disease (PD) affects cortical structures and neurophysiology. How these deviations from normative variants relate to the neurochemical systems of the cortex in a manner corresponding to motor and cognitive symptoms is unknown. We measured cortical thickness and spectral neurophysiological alterations from structural magnetic resonance imaging and task-free magnetoencephalography in patients with idiopathic PD (NMEG = 79; NMRI = 65), contrasted with similar data from matched healthy controls (NMEG = 65; NMRI = 37). Using linear mixed-effects models and cortical atlases of 19 neurochemical systems, we found that the structural and neurophysiological alterations of PD align with several receptor and transporter systems (acetylcholine, serotonin, glutamate, and noradrenaline) albeit with different implications for motor and non-motor symptoms. Some neurophysiological alignments are protective of cognitive functions: the alignment of broadband power increases with acetylcholinergic systems is related to better attention function. However, neurochemical alignment with structural and other neurophysiological alterations is associated with motor and psychiatric impairments, respectively. Collectively, the present data advance understanding of the association between the nature of neurophysiological and structural cortical alterations in PD and the symptoms that are characteristic of the disease. They also demonstrate the value of a new nested atlas modeling approach to advance research on neurological and neuropsychiatric diseases.

Baseline free water within the visual processing system predicts future psychosis in Parkinson disease

BACKGROUND AND PURPOSE

As psychosis is associated with decreased quality of life, increased institutionalization, and mortality in Parkinson disease (PD), it is essential to identify individuals at risk for future psychosis. This longitudinal study aimed to investigate whether diffusion tensor imaging (DTI) metrics of white matter hold independent utility for predicting future psychosis in PD, and whether they could be combined with clinical predictors to improve the prognostication of PD psychosis.

METHODS

This study included 123 newly diagnosed PD patients collected in the Parkinson's Progression Markers Initiative. Tract-based spatial statistics were used to compare baseline DTI metrics between PD patients who developed psychosis and those who did not during follow-up. Binary logistic regression analyses were performed to identify the clinical and white matter markers predictive of psychosis.

RESULTS

Among DTI measures, both higher baseline whole brain (odds ratio [OR] = 1.711, p = 0.016) free water (FW) and visual processing system (OR = 1.680, p < 0.001) FW were associated with an increased risk of future psychosis. Baseline FW remained a significant indicator of future psychosis in PD after controlling for clinical predictors. Moreover, the accuracy of prediction of psychosis using clinical predictors alone (area under the curve [AUC] = 0.742, 95% confidence interval [CI] = 0.655-0.816) was significantly improved by the addition of the visual processing system FW (AUC = 0.856, 95% CI = 0.781-0.912; Delong method, p = 0.022).

CONCLUSIONS

Baseline FW of the visual processing system incurs an independent risk of future psychosis in PD, thus providing an opportunity for multiple-modality marker models to include a white matter marker.

Neuropathological correlates of neuropsychiatric symptoms in dementia

INTRODUCTION

Neuropsychiatric symptoms (NPS) are common in Lewy body disease (LBD), but their etiology is poorly understood.

METHODS

In a population-based post mortem study neuropathological data was collected for Lewy body (LB) neuropathology, neurofibrillary tangles (NFT), amyloid beta burden, TDP-43, lacunar infarcts, cerebral amyloid angiopathy (CAA), and hyaline atherosclerosis. Post mortem interviews collected systematic information regarding NPS and cognitive status. A total of 1038 cases were included: no pathology (NP; n = 761), Alzheimer's disease (AD; n = 189), LBD (n = 60), and AD+LBD (n = 28).

RESULTS

Hallucinations were associated with higher LB Braak stages, while higher NFT Braak staging was associated with depression, agitation, and greater number of symptoms in the Neuropsychiatric Inventory. Cases with dual AD+LBD pathology had the highest risk of hallucinations, agitation, apathy, and total symptoms but a multiplicative interaction between these pathologies was not significant.

DISCUSSION

LB and AD pathology contribute differentially to NPS likely with an additive process contributing to the increased burden of NPS.

Grey matter volume loss in Parkinson's disease psychosis and its relationship with serotonergic gene expression: A meta-analysis

BACKGROUND

Neuroanatomical alterations underlying psychosis in Parkinson's Disease (PDP) remain unclear. We carried out a meta-analysis of MRI studies investigating the neural correlates of PDP and examined its relation with dopaminergic and serotonergic receptor gene expression.

METHODS

PubMed, Web of Science and Embase were searched for MRI studies (k studies = 10) of PDP compared to PD patients without psychosis (PDnP). Seed-based d Mapping with Permutation of Subject Images and multiple linear regression analyses was used to examine the relationship between pooled estimates of grey matter volume (GMV) loss in PDP and D1/D2 and 5-HT1a/5-HT2a receptor gene expression estimates from Allen Human Brain Atlas.

RESULTS

We observed lower grey matter volume in parietal-temporo-occipital regions (PDP n = 211, PDnP, n = 298). GMV loss in PDP was associated with local expression of 5-HT1a (b = 0.109, p = 0.012) and 5-HT2a receptors (b= -0.106, p = 0.002) but not dopaminergic receptors.

CONCLUSION

Widespread GMV loss in the parieto-temporo-occipital regions may underlie PDP. Association between grey matter volume and local expression of serotonergic receptor genes may suggest a role for serotonergic receptors in PDP.

Bidirectional Mendelian randomization study of psychiatric disorders and Parkinson’s disease

Introduction

Although the relationship between psychiatric disorders and Parkinson’s disease (PD) has attracted continuous research attention, the causal linkage between them has not reached a definite conclusion.

Methods

To identify the causal relationship between psychiatric disorders and PD, we used public summary-level data from the most recent and largest genome-wide association studies (GWASs) on psychiatric disorders and PD to conduct a bidirectional two-sample Mendelian randomization (MR). We applied stringent control steps in instrumental variable selection using the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) method to rule out pleiotropy. The inverse-variance weighted (IVW) method was used to identify the causal relationship between psychiatric disorders and PD. Multiple MR analysis methods, including MR-Egger, weighted-median, and leave-one-out analyses, were used for sensitivity analysis, followed by heterogeneity tests. Further validation and reverse MR analyses were conducted to strengthen the results of the forward MR analysis.

Results

The lack of sufficient estimation results could suggest a causal relationship between psychiatric disorders and PD in the forward MR analysis. However, the subsequent reverse MR analysis detected a causal relationship between PD and bipolar disorder (IVW: odds ratios [OR] =1.053, 95% confidence interval [CI] =1.02–1.09, p = 0.001). Further analysis demonstrated a causal relationship between genetically predicted PD and the risk of bipolar disorder subtype. No pleiotropy or heterogeneity was detected in the analyses.

Discussion

Our study suggested that while psychiatric disorders and traits might play various roles in the risk of developing PD, PD might also be involved in the risk of developing psychiatric disorders.

Non-visual hallucinations in Parkinson's disease: a systematic review

BACKGROUND

Non-visual hallucinations in Parkinson's disease (PD) can be prevalent and distressing. Most existing research has however, focused on visual hallucinations as well as related risk factors. The current study thus conducted a systematic review to collate existing evidence on non-visual hallucinations in PD, focusing on their prevalence, phenomenology, and clinical-cognitive correlates.

METHODS

Ninety-one relevant studies were included from a systematic search across PsycINFO APA, PubMed, and Web of Science, for peer-reviewed publications in the English language, from 1970 to the present. These comprised a mix of case (30 studies; n = 56) and group design (62 studies; n = 7346) studies, divided into three somewhat overlapping collections to address our three research foci.

RESULTS

Prevalence estimates for hallucinations were: auditory 1.5-72.0%, olfactory 1.6-21.0%, somatic-tactile 0.4-22.5%, gustatory 1.0-15.0%, and sensed presence 0.9-73.3%. Phenomenological inquiries revealed descriptions of vivid, consuming events replete with elaborate detail, adversely affecting PD patients in different ways. Overt experiences of multisensory hallucinations were also highly variable (0.4-80%) but exceedingly common, reported by almost half of the 45 included prevalence studies. There was some evidence for modality-specific hallucination predictors, but this was largely tentative, pending robust replication.

CONCLUSIONS

Marked prevalence figures coupled with phenomenological descriptions implicating distress denote that non-visual and multisensory hallucinations in PD are of clinical significance. More direct research and clinical attention need to be devoted to the study and management of such hallucinatory experiences.

Comprehensive Evaluation of Psychotic Features and Their Clinical Correlates in Early Parkinson's Disease

BACKGROUND

Some reports suggest that psychotic features may occur in the early stages of Parkinson's disease (PD), but sensitive tools have not been utilized.

OBJECTIVE

The aim was to evaluate the presence of psychotic symptoms using detailed scales and to assess the association with clinical characteristics.

METHODS

Healthy controls and patients within three years of PD onset were recruited. Participants were examined for psychotic symptoms using two different instruments: the Comprehensive Assessment of At-Risk Mental States (CAARMS) and a 10 question PD specific psychosis severity scale (10PDQ). In the PD group, medication use, motor and non-motor symptoms were documented.

RESULTS

Based on CAARMS and 10PDQ scales, psychotic features were present in 39% (27/70) of patients and 4% (3/74) of controls. The prevalence of passage hallucinations and illusions was significantly higher in PD compared to the control group. The presence of PD-associated psychotic features was not significantly affected by medication, motor severity or global cognitive status. Higher prevalence of overall non-motor manifestations, REM sleep behavior disorder (RBD) and depressive symptoms was significantly associated with the manifestation of psychotic features in PD [(adjusted OR:1.3; 95% CI:1.1-1.6; p = 0.003), (adjusted OR:1.3; 95% CI:1.0-1.6; p = 0.023), and (adjusted OR:1.2; 95% CI:1.0-1.4;p = 0.026)].

CONCLUSIONS

Psychotic phenomena mainly of minor nature are highly common in early PD. Cumulative non-motor symptoms, RBD and depressive features are associated with the presence of psychotic symptoms in this non-demented, early-stage PD population. More studies are needed to clarify the mechanisms that contribute to the onset of psychotic features in early PD.

Multimodal visual system analysis as a biomarker of visual hallucinations in Parkinson's disease

Visual hallucinations (VH) are present in up to 75% of Parkinson's disease (PD) patients. However, their neural bases and participation of the visual system in VH are not well-understood in PD. Seventy-four participants, 12 PD with VH (PDVH), 35 PD without VH (PDnoVH) and 27 controls underwent a battery of primary visual function and visual cognition tests, retinal optical coherence tomography and structural and resting-state functional brain MRI. We quantified cortical thickness with Freesurfer and functional connectivity (FC) of Visual (VIS), Fronto-Parietal (FP), Ventral Attention (VAN) and Dorsal Attention (DAN) networks with CONN toolbox. Group comparisons were performed with MANCOVA. Area Under the Curve (AUC) was computed to assess the ability of visual variables to differentiate PDVH and PDnoVH. There were no significant PDVH vs PDnoVH differences in disease duration, motor manifestations, general cognition or dopamine agonist therapy (DA) use. Compared to PDnoVH and HC, and regardless of DA use, PDVH showed significantly reduced contrast sensitivity, visuoperceptive and visuospatial abilities, increased retina photoreceptor layer thickness, reduced cortical thickness mostly in right visual associative areas, decreased between-network VIS-VAN and VAN-DAN connectivity and increased within-network DAN connectivity. The combination of clinical and imaging variables that best discriminated PDVH and PDnoVH (highest AUC), where within-network DAN FC, photoreceptor layer thickness and cube analysis test from Visual Object and Space Perception Battery (accuracy of 81.8%). Compared to PDnoVH, PDVH have specific functional and structural abnormalities within the visual system, which can be quantified non-invasively and could potentially constitute biomarkers for VH in PD.

Assessing the risks of treatment in Parkinson disease psychosis: An in-depth analysis

BACKGROUND

Parkinson disease (PD) psychosis (PDP) is a disabling non-motor symptom. Pharmacologic treatment is limited to pimavanserin, quetiapine, and clozapine, which do not worsen parkinsonism. A Food and Drug Administration black box warning exists for antipsychotics, suggesting increased mortality in elderly patients with dementia. However, the reasons for higher mortality are unknown.

AIM

Expanding on prior work exploring mortality in treated PDP patients, we conducted a retrospective comparison to understand the links between treatment regimen, clinical characteristics, and negative outcomes.

METHODS

Electronic medical record data extraction included clinically diagnosed PD patients between 4/29/16-4/29/19 and excluded patients with primary psychiatric diagnoses or atypical parkinsonism. Mortality and clinical characteristics during the study period were compared between untreated patients and those receiving pimavanserin, quetiapine, or both agents (combination). Mortality analyses were adjusted for age, sex, levodopa equivalent daily dose (LEDD), and dementia.

RESULTS

The pimavanserin group (n = 34) had lower mortality than the untreated group (n = 66) (odds ratio = 0.171, 95% confidence interval: 0.025-0.676, p = 0.026). The untreated group had similar mortality compared to the quetiapine (n = 147) and combination (n = 68) groups. All treated groups had a higher LEDD compared to the untreated group, but no other differences in demographics, hospitalizations, medical comorbidities, medications, or laboratory values were found between the untreated and treated groups.

CONCLUSIONS

PDP patients receiving pimavanserin had lower mortality than untreated patients. We found no other clear differences in clinical characteristics to explain the mortality risk. Prospective randomized trials are needed to definitively identify the optimal PDP treatment regimen and associated risks.

Clinical features of minor hallucinations in different phenotypes of Parkinson's disease: A cross-sectional study

Background

Minor hallucinations (MHs) are the most common psychiatric symptom associated with Parkinson's disease (PDPsy), but little is known about their characteristics in different motor phenotypes, especially postural instability gait difficulty (PIGD). The aim of this study was to explore the clinical features of MHs in different subtypes of PD.

Methods

In this cross-sectional study, 213 patients with Parkinson's disease (PD) were recruited, and the data obtained included comprehensive demographics, motor subtypes, clinical scale scores, and MH contents. Motor subtypes were classified as tremor-dominant (TD), PIGD or indeterminate according to Stebbins' method.

Results

A total of 213 PD patients were included: 90 (42.3%) TD patients, 98 (46.0%) PIGD patients and 25 (11.7%) indeterminate. In total, 70 (32.9%) patients experienced MHs. Compared to patients with the TD phenotype, we found that patients with the PIGD phenotype had more severe motor and nonmotor symptoms. They also had a higher incidence of visual illusions (VIs) and a shorter MH latency.

Conclusion

Our study demonstrated that compared to patients with the TD phenotype, patients with the PIGD phenotype had a higher incidence of MHs, especially VIs, which may lead to a higher incidence of visual hallucinations (VHs). They also had a shorter latency of MHs than patients with the TD phenotype, suggesting an earlier onset of MHs and a worse prognosis.

Health care resource utilization patterns among patients with Parkinson's disease psychosis: analysis of Medicare beneficiaries treated with pimavanserin or other-atypical antipsychotics

BACKGROUND

Pimavanserin (PIM) is the only FDA-approved atypical antipsychotic (AAP) for hallucinations and delusions associated with Parkinson's disease psychosis (PDP). Comparative real-world analyses demonstrating its benefits are needed.

OBJECTIVES

To evaluate health care resource utilization (HCRU) outcomes among PDP patients treated with PIM vs. other-AAPs.

METHODS

Retrospective cohort analysis of Parts A, B, and D claims from 100% Medicare sample from 01 January 2013-31 December 2019 was conducted. PDP Patients initiating (i.e. index date) continuous monotherapy (PIM vs. other-AAPs) for ≥12-months during 01 January 2014-31 December 2018 without 12-months pre-index AAP use were selected after 1:1 propensity score matching (PSM) on 31 variables (sex, race, region, age, and 27 Elixhauser comorbidities). HCRU outcomes included: annual all-cause and psychiatric hospitalization (short-term stay, long-term stay, and SNF-stay [skilled nursing facility]) rates, annual all-cause and psychiatric-ER visit rates, mean per-patient-per-year (PPPY) hospitalizations, and average length of stay (ALOS). PIM and other-AAPs were compared using generalized linear models (GLM) controlled for demographic characteristics, comorbidities, coexisting-dementia, and coexisting insomnia.

RESULTS

Of 12,164 PDP patients, 48.41% (n = 5,889) were female, and mean age was 77 (±8.14) years. Among 1:1 matched patients (n = 842 in each), 37.8% (n = 319) on PIM vs. 49.8% (n = 420) on other-AAPs (p < .05) reported ≥1 all-cause hospitalizations, respectively. Specifically, short-term and SNF-stay among PIM patients vs. other-AAPs were: 34% (n = 286) vs. 46.2% (n = 389) and 20.2% (n = 170) vs. 31.8% (n = 267) (p < .05), respectively. Similarly, 9.6% (n = 81) of PIM vs. 14.6% (n = 123) of other-AAPs patients had ≥1 psychiatric hospitalization (p < .05). Furthermore, ≥1 all-cause and psychiatric ER visit among PIM vs. other-AAPs were 61.6% (n = 519) vs. 69.4% (n = 584) and 5.2% (n = 43) vs. 10.2% (n = 86) (p < .05), respectively. PIM also had significantly lower ALOS, and mean PPPY short-term hospitalization and SNF-stays.

CONCLUSIONS

In this analysis of PDP patients, PIM monotherapy resulted in nearly 12% and 7% lower all-cause hospitalizations and ER visits vs. other-AAPs.

Treatment for cognitive and neuropsychiatric non-motor symptoms in Parkinson's disease: current evidence and future perspectives

INTRODUCTION

Non-motor symptoms (NMS) affect patients with Parkinson's disease (PD) from the prodromal to the advanced stages. NMS phenotypes greatly vary and have a huge impact on patients' and caregivers' quality of life (QoL). The management of cognitive and neuropsychiatric NMS remains an unmet need.

AREAS COVERED

The authors, herein, review the dopaminergic and non-dopaminergic pathogenesis, clinical features, assessment, and pharmacological and non-pharmacological treatments of cognitive and neuropsychiatric NMS in PD. They discuss the current evidence and report the findings of an overview of ongoing trials on pharmacological and selected non-pharmacological strategies.

EXPERT OPINION

The treatment of cognitive and neuropsychiatric NMS in PD is poorly explored, and therapeutic options are unsatisfactory. Pharmacological treatment of cognitive NMS is based on symptomatic active principles used in Alzheimer's disease. Dopamine agonists, selective serotonin, and serotonin-norepinephrine reuptake inhibitors have some evidence on PD-related depression. Clozapine, quetiapine, and pimavanserin may be considered for psychosis in PD. Evidence on the treatment of other neuropsychiatric NMS is limited or lacking. Addressing pathophysiological and clinical issues, which hamper solid evidence on the treatment of cognitive and neuropsychiatric NMS, may reduce the impact on QoL for PD patients and their caregivers.

Perspective: Present and Future of Virtual Reality for Neurological Disorders

Since the emergence of Virtual Reality technology, it has been adopted in the field of neurology. While Virtual Reality has contributed to various rehabilitation approaches, its potential advantages, especially in diagnosis, have not yet been fully utilized. Moreover, new tides of the Metaverse are approaching rapidly, which will again boost public and research interest and the importance of immersive Virtual Reality technology. Nevertheless, accessibility to such technology for people with neurological disorders has been critically underexplored. Through this perspective paper, we will briefly look over the current state of the technology in neurological studies and then propose future research directions, which hopefully facilitate beneficial Virtual Reality studies on a wider range of topics in neurology.

Psychosis in Parkinson's disease in a Southeast Asian cohort: prevalence and clinical correlates

Introduction

Psychosis is a prominent neuropsychiatric symptom of Parkinson's disease (PD) and is associated with negative outcomes, such as poorer quality of life and greater rate of functional impairment. Early identification of patients with PD at risk of developing psychosis facilitates appropriate management to improve outcomes. However, this phenomenon has not been examined locally. This study aimed to examine the prevalence of PD-associated psychosis in the local setting, identify any associated risk factors, as well as characterise the cognitive trajectory of patients with PD with psychosis.

Methods

A retrospective cohort of 336 patients with PD, who presented to the National Neuroscience Institute, Singapore, in 2006 and 2007 and attended follow-up visits through to 2013 was analysed. The data analysed included scores from clinician assessments of cognitive function, disease severity and presence of psychotic symptoms, conducted when clinically appropriate during patients' medical visits. Survival analysis and logistic and linear regression analysis were performed.

Results

Psychosis was diagnosed in 63 patients with PD, indicating a prevalence of 18.8% for PD-associated psychosis. Incidence of psychosis in PD was calculated to be 40 per 1,000 person-years. No significant association was found between demographic variables and the odds of developing psychosis in PD. Regression analyses found that the presence of psychosis significantly predicted greater cognitive decline and disease severity.

Conclusion

Psychosis has a significant presence among the PD population in Singapore, possibly serving as an indicator of more rapid cognitive decline and progression of PD severity.

Characteristics of sleep structure in Parkinson's disease patients with hallucinations based on polysomnography

Hallucination is a common non-motor symptom in patients with Parkinson's disease (PD). Additionally, sleep disorders are associated with an increased risk of hallucinations in PD patients. This study aimed to examine the association between hallucination and objective sleep parameters in PD patients. We retrospectively recruited 278 PD patients who underwent polysomnography and clinical assessments and classified them into non-hallucination and hallucination groups. Hallucinations were observed in 77 older PD patients who had more severe motor symptoms and higher scores on the Non-Motor Symptoms Questionnaire (NMSQ), Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) but lower scores on the Montreal Cognitive Assessment (MOCA) and PD Sleep Scale (PDSS) than PD patients without hallucinations. Analysis of the polysomnographic variables in patients with hallucinations showed that they exhibited a decrease in total sleep time, sleep efficiency (SE), rapid eye movement (REM) sleep time and slow wave sleep (SWS, N3) time and percentage but a significant increase in wake time after sleep onset (WASO), periodic limb movement index (PLMI) scores, and stage 2 NREM (N2)percentage. Logistic regression analysis revealed that higher NMSQ scores, lower MOCA scores, lower SE, and a lower percentage of N3 sleep were associated with hallucinations in PD patients. Our results suggested that PD patients with hallucinations had worse sleep quality and differences in sleep architecture (measured by polysomnography).

Atlas-guided parcellation: Individualized functionally-homogenous parcellation in cerebral cortex

Resting-state Magnetic resonance imaging-based parcellation aims to group the voxels/vertices non-invasively based on their connectivity profiles, which has achieved great success in understanding the fundamental organizational principles of the human brain. Given the substantial inter-individual variability, the increasing number of studies focus on individual parcellation. However, current methods perform individual parcellations independently or are based on the group prior, requiring expensive computational costs, precise parcel alignment, and extra group information. In this work, an efficient and flexible parcellation framework of individual cerebral cortex was proposed based on a region growing algorithm by merging the unassigned and neighbor vertex with the highest-correlated parcel iteratively. It considered both consistency with prior atlases and individualized functional homogeneity of parcels, which can be applied to a single individual without parcel alignment and group information. The proposed framework was leveraged to 100 unrelated subjects for functional homogeneity comparison and individual identification, and 186 patients with Parkison's disease for symptom prediction. Results demonstrated our framework outperformed other methods in functional homogeneity, and the generated parcellations provided 100% individual identification accuracy. Moreover, the default mode network (DMN) exhibited higher functional homogeneity, intra-subject parcel reproducibility and fingerprinting accuracy, while the sensorimotor network did the opposite, reflecting that the DMN is the most representative, stable, and individual-identifiable network in the resting state. The correlation analysis showed that the severity of the disease symptoms was related negatively to the similarity of individual parcellation and the atlases of healthy populations. The disease severity can be correctly predicted using machine learning models based on individual topographic features such as parcel similarity and parcel size. In summary, the proposed framework not only significantly improves the functional homogeneity but also captures individualized and disease-related brain topography, serving as a potential tool to explore brain function and disease in the future.

Temporal Variation in Disease Onset and Clinical Features of Lewy Body Disease in China

Background: Lewy body dementia is the second most common neurodegenerative dementia, but data concerning the onset age and clinical features in the prodromal stage remain limited in China. Objective: To investigate the associations between onset age and clinical manifestations of cognitive impairment with Lewy bodies in a large-sample cohort. Methods: We included 74 patients with mild cognitive impairment with Lewy bodies (MCI-LB), 533 patients with dementia with Lewy bodies (DLB), 118 patients with Parkinson’s disease with MCI (PD-MCI), and 313 patients with Parkinson’s disease dementia (PDD) in this multicenter cohort from 22 memory clinics of China from 1 January 2018 to 31 March 2022. The onset age, clinical manifestations, and neuropsychological assessments were recorded and analyzed after reviewing the medical records. Results: The average onset age of memory loss was 68.28 (±7.00) years, and parkinsonism happened 2.00 (±1.24) years later for patients with MCI-LB. The average onset age of parkinsonism was 60.56 (±8.96) years, and the memory loss happened 3.49 (±3.02) years later for patients with PD-MCI. Rapid eye movement sleep behavior disorder and visual hallucinations were frequently reported in MCI-LB, DLB, and PDD, while visual hallucinations were least frequently reported in PD-MCI. Lower scores of MMSE and depression, and higher scores of activities of daily living and delusions, were independently associated with older onset age in DLB. Conclusion: The onset of PD-MCI precedes MCI-LB, and memory loss occurs 3 years after parkinsonism. The onset age is associated with cognition and neuropsychiatric symptoms in process.

Contribution of cognitive and bodily navigation cues to egocentric and allocentric spatial memory in hallucinations due to Parkinson's disease: A case report

Parkinson's disease (PD) manifestations can include visual hallucinations and illusions. Recent findings suggest that the coherent integration of bodily information within an egocentric representation could play a crucial role in these phenomena. Egocentric processing is a key aspect of spatial navigation and is supported by the striatum. Due to the deterioration of the striatal and motor systems, PD mainly impairs the egocentric rather than the allocentric spatial frame of reference. However, it is still unclear the interplay between spatial cognition and PD hallucinations and how different navigation mechanisms can influence such spatial frames of reference. We report the case of A.A., a patient that suffers from PD with frequent episodes of visual hallucinations and illusions. We used a virtual reality (VR) navigation task to assess egocentric and allocentric spatial memory under five navigation conditions (passive, immersive, map, path decision, and attentive cues) in A.A. and a PD control group without psychosis. In general, A.A. exhibited a statistically significant classical dissociation between the egocentric and allocentric performance with a greater deficit for the former. In particular, the dissociation was statistically significant in the “passive” and “attentive cues” conditions. Interestingly in the “immersive” condition, the dissociation was not significant and, in contrast to the other conditions, trends showed better performance for egocentric than allocentric memory. Within the theories of embodiment, we suggest that body-based information, as assessed with VR navigation tasks, could play an important role in PD hallucinations. In addition, the possible neural underpinnings and the usefulness of VR are discussed.

Deep Clinical Phenotyping of Parkinson's Disease: Towards a New Era of Research and Clinical Care

Despite recent advances in technology, clinical phenotyping of Parkinson's disease (PD) has remained relatively limited as current assessments are mainly based on empirical observation and subjective categorical judgment at the clinic. A lack of comprehensive, objective, and quantifiable clinical phenotyping data has hindered our capacity to diagnose, assess patients' conditions, discover pathogenesis, identify preclinical stages and clinical subtypes, and evaluate new therapies. Therefore, deep clinical phenotyping of PD patients is a necessary step towards understanding PD pathology and improving clinical care. In this review, we present a growing community consensus and perspective on how to clinically phenotype this disease, that is, to phenotype the entire course of disease progression by integrating capacity, performance, and perception approaches with state-of-the-art technology. We also explore the most studied aspects of PD deep clinical phenotypes, namely, bradykinesia, tremor, dyskinesia and motor fluctuation, gait impairment, speech impairment, and non-motor phenotypes.

Emerging role of psychosis in Parkinson's disease: From clinical relevance to molecular mechanisms

Parkinson’s disease (PD) is the second most common neurodegenerative disease. Psychosis is one of the common psychiatric presentations in the natural course of PD. PD psychosis is an important non-motor symptom, which is strongly correlated with a poor prognosis. Increasing attention is being given to PD psychosis. In this opinion review, we summarized and analyzed the identification, screening, epidemiology, mechanisms, risk factors, and therapeutic approaches of PD psychosis based on the current clinical evidence. PD psychosis tends to have a negative effect on patients' quality of life and increases the burden of family caregiving. Screening and identification in the early stage of disease is crucial for establishing tailored therapeutic strategies and predicting the long-term outcome. Development of PD psychosis is believed to involve a combination of exogenous and endogenous mechanisms including imbalance of neurotransmitters, structural and network changes, genetic profiles, cognitive impairment, and antiparkinsonian medications. The therapeutic strategy for PD psychosis includes reducing or ceasing the use of dopaminergic drug, antipsychotics, cholinesterase inhibitors, and non-pharmacological interventions. Ongoing clinical trials are expected to provide new insights for tailoring therapy for PD psychosis. Future research based on novel biomarkers and genetic factors may help inform individualized therapeutic strategies.

Neuroscience robotics for controlled induction and real-time assessment of hallucinations

Although hallucinations are important and frequent symptoms in major psychiatric and neurological diseases, little is known about their brain mechanisms. Hallucinations are unpredictable and private experiences, making their investigation, quantification and assessment highly challenging. A major shortcoming in hallucination research is the absence of methods able to induce specific and short-lasting hallucinations, which resemble clinical hallucinations, can be elicited repeatedly and vary across experimental conditions. By integrating clinical observations and recent advances in cognitive neuroscience with robotics, we have designed a novel device and sensorimotor method able to repeatedly induce a specific, clinically relevant hallucination: presence hallucination. Presence hallucinations are induced by applying specific conflicting (spatiotemporal) sensorimotor stimulation including an upper extremity and the torso of the participant. Another, MRI-compatible, robotic device using similar sensorimotor stimulation permitted the identification of the brain mechanisms of these hallucinations. Enabling the identification of behavioral and a frontotemporal neural biomarkers of hallucinations, under fully controlled experimental conditions and in real-time, this method can be applied in healthy participants as well as patients with schizophrenia, neurodegenerative disease or other hallucinations. The execution of these protocols requires intermediate-level skills in cognitive neuroscience and MRI processing, as well as minimal coding experience to control the robotic device. These protocols take ~3 h to be completed.

Systematic review for the prevention and management of falls and fear of falling in patients with Parkinson's disease

OBJECTIVE

To synthesize recent empirical evidence for the prevention and management of falls and fear of falling in patients with Parkinson's disease (PD).

DATA SOURCE

Database from PubMed, Cochrane Library, and EMBASE.

STUDY DESIGN

Systematic review.

DATA COLLECTION

We searched the PubMed, Cochrane Library, and EMBASE databases for studies published from inception to February 27, 2021. Inclusion criteria were nonreview articles on prevention and management measures related to falls and fall prevention in Parkinson's disease patients.

PRINCIPAL FINDINGS

We selected 45 articles and conducted in-depth research and discussion. According to the causes of falls in PD patients, they were divided into five directions, namely physical status, pre-existing conditions, environment, medical care, and cognition. In the cognitive domain, we focused on the fear of falling. On the above basis, we constructed a fall prevention model, which is a tertiary prevention health care network, based on The Johns Hopkins Fall Risk Assessment Tool to provide ideas for the prevention and management of falling and fear of falling in PD patients in clinical practice CONCLUSIONS: Falls and fear of falls in patients with Parkinson's disease can be reduced by effective clinical prevention and management. Future studies are needed to explore the efficacy of treatment and prevention of falls and fear of falls.