Feeling of presence in Parkinson's disease

Felt presence and its determinants in young adults: results from three independent samples

Felt presence (FP) is a phenomenon that might appear in individuals with mental and neurological disorders as well as those without any specific morbidity. Some studies have indicated that FP is closely related to psychotic symptomatology. Yet, the mechanisms underlying its occurrence remain largely unknown. The present study aimed to disentangle as to whether FP is associated with widely known risk factors of psychosis. Data from three independent samples of non-clinical young adults were analyzed. Self-reports were administered to assess psychopathological symptoms (samples 1 - 3), neurodevelopmental risk factors for psychosis (sample 1), social defeat components (sample 2), childhood trauma and loneliness (sample 3). A total of 4782 individuals were surveyed across all three samples. Unadjusted analyses showed that the following factors are associated with higher odds of FP: obstetric complications, childhood trauma, non-right handedness, a lower education level, unemployment, minority status, humiliation, perceived constraints, and loneliness. However, only minority status and a lower level of education were associated with higher odds of FP after adjustment for other psychopathological symptoms, age, and gender. Importantly, hallucination-like experiences across all recorded modalities and paranoia were associated with higher odds of FP in all samples. Depressive symptoms were weakly associated with FP in two samples. Findings from the present study suggest that the majority of known risk factors for psychosis contribute to the emergence of FP through the effects on psychotic experiences. Low educational attainment and minority status might be the only risk factors independently contributing to the emergence of FP.

Real-time fMRI neurofeedback modulates induced hallucinations and underlying brain mechanisms

Hallucinations can occur in the healthy population, are clinically relevant and frequent symptoms in many neuropsychiatric conditions, and have been shown to mark disease progression in patients with neurodegenerative disorders where antipsychotic treatment remains challenging. Here, we combine MR-robotics capable of inducing a clinically-relevant hallucination, with real-time fMRI neurofeedback (fMRI-NF) to train healthy individuals to up-regulate a fronto-parietal brain network associated with the robotically-induced hallucination. Over three days, participants learned to modulate occurrences of and transition probabilities to this network, leading to heightened sensitivity to induced hallucinations after training. Moreover, participants who became sensitive and succeeded in fMRI-NF training, showed sustained and specific neural changes after training, characterized by increased hallucination network occurrences during induction and decreased hallucination network occurrences during a matched control condition. These data demonstrate that fMRI-NF modulates specific hallucination network dynamics and highlights the potential of fMRI-NF as a novel antipsychotic treatment in neurodegenerative disorders and schizophrenia.

Parkinson's Disease Psychosis and the Marketing of Pimavanserin

In 2016, Nuplazid (pimavanserin) became the first FDA-approved treatment for Parkinson's Disease Psychosis (PDP). We explored the possibility that PDP was a term created to market Nuplazid. We examined trends in perceptions of psychosis in Parkinson's disease from the 1990s to 2020 through MEDLINE search term frequency, neurology textbooks, guidance from professional societies, Acadia annual reports, sponsored websites, and a sponsored meeting held by the National Institutes of Health (NIH). We analyzed continuing medical education (CME) activities on PDP and analyzed the connection between payments by the manufacturer of pimavanserin and prescriptions. Our analysis of nine sponsored CME activities reveals misleading themes, including: PDP is common, progressive, and not always drug-induced; there is no such thing as a benign hallucination, and psychotic symptoms always worsen; PDP increases mortality; and competing treatments are ineffective or dangerous while pimavanserin is safe and effective for treating PDP. Industry-sponsored CME was used to disseminate inaccurate and misleading marketing messages on psychosis related to Parkinson's disease. Some professional societies and some textbooks also resisted the PDP label. Reframing PDP as a unique condition is a typical example of condition branding. The establishment of PDP expanded the use of pimavanserin and is likely to have resulted in many avoidable deaths.

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.

The experience of felt presence in a general population sample

Felt presence is a widely occurring experience, but remains under-recognised in clinical and research practice. To contribute to a wider recognition of the phenomenon, we aimed to assess the presentation of felt presence in a large population sample (n = 10 447) and explore its relation to key risk factors for psychosis. In our sample 1.6% reported experiencing felt presence in the past month. Felt presence was associated with visual and tactile hallucinations and delusion-like thinking; it was also associated with past occurrence of adverse events, loneliness and poor sleep. The occurrence of felt presence may function as a marker for general hallucination proneness.

Numerosity estimation of virtual humans as a digital-robotic marker for hallucinations in Parkinson's disease

Hallucinations are frequent non-motor symptoms in Parkinson's disease (PD) associated with dementia and higher mortality. Despite their high clinical relevance, current assessments of hallucinations are based on verbal self-reports and interviews that are limited by important biases. Here, we used virtual reality (VR), robotics, and digital online technology to quantify presence hallucination (vivid sensations that another person is nearby when no one is actually present and can neither be seen nor heard) in laboratory and home-based settings. We establish that elevated numerosity estimation of virtual human agents in VR is a digital marker for experimentally induced presence hallucinations in healthy participants, as confirmed across several control conditions and analyses. We translated the digital marker (numerosity estimation) to an online procedure that 170 PD patients carried out remotely at their homes, revealing that PD patients with disease-related presence hallucinations (but not control PD patients) showed higher numerosity estimation. Numerosity estimation enables quantitative monitoring of hallucinations, is an easy-to-use unobtrusive online method, reaching people far away from medical centers, translating neuroscientific findings using robotics and VR, to patients' homes without specific equipment or trained staff.

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.

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.

Prevalence of hallucinations in Parkinson's patients: meta-analysis of International studies

BACKGROUND

Parkinson's disease (PD) is one of the common causes of disability in the elderly. This study aims to estimate the prevalence of hallucinations in Parkinson's patients in the world.

METHODS

A systematic review of PubMed/Medline, ISI Web of Knowledge, and Google Scholar was conducted from 2017 to 2022. This study investigated the prevalence of hallucinations in Parkinson's patients. Point prevalence was analyzed with a 95% confidence interval. The variances of each study were calculated using the binomial distribution formula The researcher used Cochrane Q-test with a significance level of less than 0.1 to check the heterogeneity between studies and the change index assigned to heterogeneity I2. Due to the heterogeneity between the studies, the random effects model was used to combine the results of the studies. All statistical analyses were performed by STATA version 14 software using meta-analysis commands.

RESULTS

Reports indicated that the prevalence of hallucinations in Parkinson's patients in 32 studies was 28% (0.22-0.34 = 95%CI). The highest prevalence was 34% and 95% CI = 0.07- 0.61 in developing countries and 27% with CI = 0.33-0.21 in developed countries. Reports showed the prevalence in men was 30% (CI = 0.22-0.38) and in women 23% (95% CI = 0.14-0.31).

CONCLUSIONS

Considering the relatively high prevalence of hallucinations in these patients, checking up for the presence of hallucinations on every visit of Parkinson's patients is recommended, and providing appropriate treatment for that is necessary.

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.

The diagnostic performance of functional dopaminergic scintigraphic imaging in the diagnosis of dementia with Lewy bodies: an updated systematic review

INTRODUCTION

Dopaminergic scintigraphic imaging is a cornerstone to support the diagnosis in dementia with Lewy bodies. To clarify the current state of knowledge on this imaging modality and its impact on clinical diagnosis, we performed an updated systematic review of the literature.

METHODS

This systematic review was carried out according to PRISMA guidelines. A comprehensive computer literature search of PubMed/MEDLINE, EMBASE, and Cochrane Library databases for studies published through June 2022 was performed using the following search algorithm: (a) "Lewy body" [TI] OR "Lewy bodies" [TI] and (b) ("DaTscan" OR "ioflupane" OR "123ip" OR "123?ip" OR "123 ip" OR "123i-FP-CIT" OR "FPCIT" OR "FP-CIT" OR "beta?CIT" OR "beta CIT" OR "CIT?SPECT" OR "CIT SPECT" OR "Dat?scan*" OR "dat scan*" OR "dat?spect*" OR "SPECT"). Risk of bias and applicability concerns of the studies were evaluated using the QUADAS-2 tool.

RESULTS

We performed a qualitative analysis of 59 studies. Of the 59 studies, 19 (32%) addressed the diagnostic performance of dopamine transporter imaging, 15 (25%) assessed the identification of dementia with Lewy bodies in the spectrum of Lewy body disease and 18 (31%) investigated the role of functional dopaminergic imaging in distinguishing dementia with Lewy bodies from other dementias. Dopamine transporter loss was correlated with clinical outcomes in 19 studies (32%) and with other functional imaging modalities in 15 studies (25%). Heterogeneous technical aspects were found among the studies through the use of various radioligands, the more prevalent being the [123I]N‑ω‑fluoropropyl‑2β‑carbomethoxy‑3β‑(4‑iodophenyl) nortropane (123I-FP-CIT) in 54 studies (91.5%). Image analysis used visual analysis (9 studies, 15%), semi-quantitative analysis (29 studies, 49%), or a combination of both (16 studies, 27%).

CONCLUSION

Our systematic review confirms the major role of dopaminergic scintigraphic imaging in the assessment of dementia with Lewy bodies. Early diagnosis could be facilitated by identifying the prodromes of dementia with Lewy bodies using dopaminergic scintigraphic imaging coupled with emphasis on clinical neuropsychiatric symptoms. Most published studies use a semi-quantitative analytical assessment of tracer uptake, while there are no studies using quantitative analytical methods to measure dopamine transporter loss. The superiority of a purely quantitative approach to assess dopaminergic transmission more accurately needs to be further clarified.

The felt-presence experience: from cognition to the clinic

The felt presence experience is the basic feeling that someone else is present in the immediate environment, without clear sensory evidence. Ranging from benevolent to distressing, personified to ambiguous, felt presence has been observed in neurological case studies and within psychosis and paranoia, associated with sleep paralysis and anxiety, and recorded within endurance sports and spiritualist communities. In this Review, we summarise the philosophical, phenomenological, clinical, and non-clinical correlates of felt presence, as well as current approaches that use psychometric, cognitive, and neurophysiological methods. We present current mechanistic explanations for felt presence, suggest a unifying cognitive framework for the phenomenon, and discuss outstanding questions for the field. Felt presence offers a sublime opportunity to understand the cognitive neuroscience of own-body awareness and social agency detection, as an intuitive, but poorly understood, experience in health and disorder.

Social Deafferentation and the Relation Between Loneliness and Hallucinations

BACKGROUND AND HYPOTHESIS

The social deafferentation hypothesis (SDA) has been proposed as an explanatory mechanism of hallucinations, based on the theory that social withdrawal triggers the initial phase of schizophrenia. The current study tests the SDA by assessing how loneliness is associated with different types of hallucinations. Under the SDA, increased loneliness is hypothesized to affect the occurrence of hallucinations that carry social meaning, but not of nonsocial hallucinations.

STUDY DESIGN

As part of an online survey, 2038 adolescents and young adults from the general population (median age 21 years; 75% female) filled out the Questionnaire for Psychotic Experiences, and the shortened De Jong Gierveld Loneliness Scale. Binomial logistic regression was used to investigate the effects of loneliness severity on past month prevalence of hallucinations, and on the presence of social versus nonsocial hallucinations.

STUDY RESULTS

Loneliness increased the prevalence of hallucinations across modalities in the past month. Moreover, stronger degree of loneliness increased the likelihood of hearing voices or laughter, and of hallucinating being touched. Conversely, loneliness decreased the likelihood of experiencing the nonsocial hallucination of a tingling feeling. As expected, loneliness did not increase the prevalence of experiencing nonsocial hallucinations. Surprisingly, neither was loneliness associated with experiencing felt presence.

CONCLUSIONS

Our results are novel in showing that loneliness specifically increases the likelihood of hearing human sounds such as voices or laughter, or feeling a human touch. Hallucinations without social meaning were not more likely to be experienced with increasing loneliness. This forms a confirmation of the SDA.

Sensed Presence, Attenuated Psychosis, and Transliminality: At the Threshold of Consciousness

INTRODUCTION

The experience of "sensed presence" or "felt presence" in the absence of "other" has been described as a complex multimodal experience to which meaning is given. Sensed presence (SenP) is a transdiagnostic experience that exists along a continuum that can appear during isolation, spirit quests, exposure to extreme elements, bereavement, anxiety, and psychosis. Given the prevalence and vast heterogeneity of SenP, in addition to a surprising lack of targeted research into this phenomenon, this research examined the interrelationship of SenP, attenuated psychosis symptoms (APS), and transliminality. Transliminality is composed of absorption, fantasy proneness, paranormal belief, mystical experiences, increased creativity, and hyperaesthesia.

METHODS

A completely anonymous online survey of unusual experiences and mental health was distributed via social media (i.e., Twitter, Facebook, Reddit, and mass emailing lists) to recruit participants. Demographic data were analyzed using χ2 tests and one-way ANOVAs. A two-step cluster analysis was conducted to identify distinct sub-categories of transliminality followed by ANOVAs with bootstrapping at 1,000 iterations to compare SenP, increased APS, and transliminality. Pearson's bivariate correlations were conducted to determine the association between SenP, APS, and transliminality.

RESULTS

Together with descriptive findings, we show distinct characteristics between clusters. T1 cluster consisted of individuals with few SenP experiences, low APS, and low transliminality. T2 consisted of individuals with a moderate prevalence of SenP, low APS, moderate transliminality, and increased overall feeling of closeness to G-d. There was no significant difference in APS between T1 and T2 or in the level of distress associated with APS. T3 individuals showed a significantly higher prevalence of SenP in all domains (frequency, distress, vividness, and total score), higher APS, and higher transliminality, compared to T1 and T2. The T3 cluster met criteria for high risk to develop psychosis.

CONCLUSION

Thus, our findings demonstrate a strong association and entanglement of these experiences which suggests that the interrelatedness of transliminality/absorption and APS may serve as a potentially provocative underlying structure in the phenomenology of SenP.

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.

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.

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.

Psychosis as a Treatment Target in Dementia: A Roadmap for Designing Interventions

Psychotic phenomena are among the most severe and disruptive symptoms of dementias and appear in 30% to 50% of patients. They are associated with a worse evolution and great suffering to patients and caregivers. Their current treatments obtain limited results and are not free of adverse effects, which are sometimes serious. It is therefore crucial to develop new treatments that can improve this situation. We review available data that could enlighten the future design of clinical trials with psychosis in dementia as main target. Along with an explanation of its prevalence in the common diseases that cause dementia, we present proposals aimed at improving the definition of symptoms and what should be included and excluded in clinical trials. A review of the available information regarding the neurobiological basis of symptoms, in terms of pathology, neuroimaging, and genomics, is provided as a guide towards new therapeutic targets. The correct evaluation of symptoms is transcendental in any therapeutic trial and these aspects are extensively addressed. Finally, a critical overview of existing pharmacological and non-pharmacological treatments is made, revealing the unmet needs, in terms of efficacy and safety. Our work emphasizes the need for better definition and measurement of psychotic symptoms in dementias in order to highlight their differences with symptoms that appear in non-dementing diseases such as schizophrenia. Advances in neurobiology should illuminate the development of new, more effective and safer molecules for which this review can serve as a roadmap in the design of future clinical trials.

Minor hallucinations in isolated rapid eye movement sleep behavior disorder indicative of early phenoconversion: A preliminary study

OBJECTIVES

Minor hallucinations (MH) are psychotic symptoms that can occur anywhere between prodromal to early Parkinson's disease and after onset of motor problems. MH include visual illusions, presence hallucinations, and passage hallucinations. Isolated rapid eye movement sleep behavior disorder (RBD) is a harbinger of neurodegenerative diseases. We conducted a retrospective cohort study to investigate the clinical characteristics of isolated RBD with MH and the risk of phenoconversion.

MATERIALS AND METHODS

We retrospectively analyzed the data of 36 patients with isolated RBD (four females; median age, 75.0 years). We defined cases reporting at least one minor hallucination as RBD with MH. Demographic data and cognitive function were compared between patients with and without MH, and Cox proportional hazards models estimated the risk of phenoconversion.

RESULTS

We included 10 (27.8%) patients with MH and 26 (72.2%) without MH. Patients with MH were older, had less dopamine transporter accumulation, more severe autonomic dysfunction, more depressive symptoms, and lower verbal fluency and symbol coding test scores than patients without MH. After follow-up (median, 2.50 years), 13.9% (5/36) of all patients developed phenoconversion (Parkinson's disease, two patients; dementia with Lewy bodies, three patients). The rate of phenoconversion was significantly higher in patients with MH (40.0% vs. 3.8%, p = .005). The Cox proportional hazards model adjusted for age, sex, and disease duration revealed that MH was a significant risk factor for phenoconversion (hazard ratio, 14.72; 95% confidence interval, 1.35-160.5).

CONCLUSIONS

Minor hallucinations may be utilized as early clinical markers for prodromal estimation of neurodegenerative diseases.

Clinical Characteristics of Minor Hallucinations in Chinese Parkinson's Disease Patients

Background

Psychotic symptoms are common in Parkinson's disease (PD). However, the clinical characteristics of PD psychosis (PDP) have been rarely reported in Chinese PD patients. We aimed to categorize PDP in a PD cohort and its relationship to other clinical characteristics.

Methods

A total of 149 Chinese PD patients were consecutively enrolled, and idiopathic PD patients were recruited in the study. The symptoms of PDP were assessed with the enhanced Scale for the Assessment of Positive Symptoms in PD. Then, the patients were classified into a PD-control group, isolated minor hallucination (MH) group, and complex MH group, and clinical and demographic data of different groups were compared.

Results

Parkinson's disease psychosis was present in 40.3% (60/149) of our patients. The most common PDPs were MHs, present in 32.9% (49 of 149) of the cohort. Compared to patients without MHs, patients with MHs were older, had a longer disease duration, a higher levodopa equivalent daily dose, more severe motor symptoms, dyskinesia, a higher rate of rapid eye movement sleep behavior disorders, frontal lobe function impairments, and a higher percentage of cognitive impairment. Logistic regression analysis showed that advanced Hoehn-Yahr stage [odds ratio (OR): 2.697, p = 0.007)] and frontal lobe function impairment (OR: 0.684, p = 0.003) were independent risk factors for MHs.

Conclusion

MHs were frequent non-motor symptoms in PD patients. It was associated with increased motor and non-motor symptom burdens and reduced quality of life. MHs have been called “minor,” but they have major clinical and prognostic implications and need early screening.

Frequency and Characteristics of Psychosis in Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Psychotic symptoms are highly frequent in Parkinson's disease (PD) patients and are associated with poor prognosis. They include hallucinations, delusions, and minor psychotic phenomena, including sense of presence, passage hallucinations, and illusions.

OBJECTIVE

To evaluate the frequency of psychosis in PD patients.

METHODS

A systematic review and meta-analysis of clinical trials, prospective and retrospective cohort studies, case-control studies, and cross-sectional studies reporting the frequency of psychosis, hallucinations, and delusions in PD.

RESULTS

Electronic database search wielded 3536 articles, an additional 91 were identified through citation chaining. Of these, 163 were fully inspected, 57 removed, and 106 included as relevant for neuropsychiatric events frequency, with 32 meeting our inclusion criteria (psychosis and/or specific psychotic phenomena). The pooled frequency of psychosis was 20.7% (95% CI 14.5 to 28.6; I2 = 94%, 15 studies; combined n = 2919). None of the pre-defined meta-regressions or subgroup analyses were statistically significant or helped explain the statistical heterogeneity. The pooled frequency of any form of hallucination was 21.6% (95% CI 14.7 to 30.6; I2 = 95%; 18 studies; combined n = 3161). Duration of PD at baseline and mean baseline Hoehn & Yahr stage helped explain the statistical heterogeneity in the meta-analysis of hallucinations.

CONCLUSION

Based on the available evidence, around a fifth of PD patients experience psychosis or hallucinations. The risk of developing hallucinations is likely moderated by the disease duration, Hoehn & Yahr stage, and the cognitive status.

Phantom boarder symptom in elderly Japanese

BACKGROUND

Phantom boarder symptom (PBS) is classified as a delusional misidentification syndrome, and is often encountered in elderly individuals who have mild or major neurocognitive disorders. With the ageing of society, patients presenting with PBS are increasing in Japan. This retrospective study was conducted to examine the aetiology and identify significant predictors of PBS.

METHODS

The records of 511 consecutive patients who visited our hospital with suspicion of dementia between September 2013 and September 2019 were retrospectively examined. From those, 16 patients who presented with PBS (1 male, 15 females; mean age 79.9 ± 4 years) were selected and case features were investigated in detail. Clinical symptoms, background factors, and final diagnoses were noted. PBS was most common in patients affected by dementia with Lewy bodies (DLB). Predictive factors were evaluated using multiple logistic regression analysis.

RESULTS

The final diagnosis of the 16 subjects was DLB in 7, Alzheimer's disease in 3, delusional disorder in 3, unspecified dementia in 2, and vascular dementia in 1. Analysis limited to DLB cases showed that a low Mini-Mental State Examination (MMSE) score and living alone were related to higher risk for PBS.

CONCLUSION

Various types of dementia, especially DLB, as well as cognitive impairment and living alone were found to be strong predictors of PBS.

Robotically-induced hallucination triggers subtle changes in brain network transitions

The perception that someone is nearby, although nobody can be seen or heard, is called presence hallucination (PH). Being a frequent hallucination in patients with Parkinson's disease, it has been argued to be indicative of a more severe and rapidly advancing form of the disease, associated with psychosis and cognitive decline. PH may also occur in healthy individuals and has recently been experimentally induced, in a controlled manner during fMRI, using MR-compatible robotics and sensorimotor stimulation. Previous neuroimaging correlates of such robot-induced PH, based on conventional time-averaged fMRI analysis, identified altered activity in the posterior superior temporal sulcus and inferior frontal gyrus in healthy individuals. However, no link with the strength of the robot-induced PH was observed, and such activations were also associated with other sensations induced by robotic stimulation. Here we leverage recent advances in dynamic functional connectivity, which have been applied to different psychiatric conditions, to decompose fMRI data during PH-induction into a set of co-activation patterns that are tracked over time, as to characterize their occupancies, durations, and transitions. Our results reveal that, when PH is induced, the identified brain patterns significantly and selectively increase their transition probabilities towards a specific brain pattern, centred on the posterior superior temporal sulcus, angular gyrus, dorso-lateral prefrontal cortex, and middle prefrontal cortex. This change is not observed in any other control conditions, nor is it observed in association with other sensations induced by robotic stimulation. The present findings describe the neural mechanisms of PH in healthy individuals and identify a specific disruption of the dynamics of network interactions, extending previously reported network dysfunctions in psychotic patients with hallucinations to an induced robot-controlled specific hallucination in healthy individuals.

Fronto-Temporal Disconnection Within the Presence Hallucination Network in Psychotic Patients With Passivity Experiences

Psychosis, characterized by hallucinations and delusions, is a common feature of psychiatric disease, especially schizophrenia. One prominent theory posits that psychosis is driven by abnormal sensorimotor predictions leading to the misattribution of self-related events. This misattribution has been linked to passivity experiences (PE), such as loss of agency and, more recently, to presence hallucinations (PH), defined as the conscious experience of the presence of an alien agent while no person is actually present. PH has been observed in schizophrenia, Parkinson's disease, and neurological patients with brain lesions and, recently, the brain mechanisms of PH (PH-network) have been determined comprising bilateral posterior middle temporal gyrus (pMTG), inferior frontal gyrus (IFG), and ventral premotor cortex (vPMC). Given that the experience of an alien agent is a common feature of PE, we here analyzed the functional connectivity within the PH-network in psychotic patients with (N = 39) vs without PE (N = 26). We observed reduced fronto-temporal functional connectivity in patients with PE compared to patients without PE between the right pMTG and the right and left IFG of the PH-network. Moreover, when seeding from these altered regions, we observed specific alterations with brain regions commonly linked to auditory-verbal hallucinations (such as Heschl's gyrus). The present connectivity findings within the PH-network extend the disconnection hypothesis for hallucinations to the specific case of PH and associates the PH-network with key brain regions for frequent psychotic symptoms such as auditory-verbal hallucinations, showing that PH are relevant to the study of the brain mechanisms of psychosis and PE.

Parkinsonism and dementia

The aim of the present review is to summarize literature data on dementia in parkinsonian disorders. Cognitive decline and the gradual development of dementia are considered to be key features in the majority of parkinsonian conditions. The burden of dementia in everyday life of parkinsonian patients and their caregivers is vast and can be even more challenging to handle than the motor component of the disease. Common pathogenetic mechanisms involve the aggregation and spreading of abnormal proteins like alpha-synuclein, tau or amyloid in cortical and subcortical regions with subsequent dysregulation of multiple neurotransmitter systems. The degree of cognitive deterioration in these disorders is variable and ranges from mild cognitive impairment to severe cognitive dysfunction. There is also variation in the number and type of affected cognitive domains which can involve either a single domain like executive or visuospatial function or multiple ones. Novel genetic, biological fluid or imaging biomarkers appear promising in facilitating the diagnosis and staging of dementia in parkinsonian conditions. A significant part of current research in Parkinson's disease and other parkinsonian syndromes is targeted towards the cognitive aspects of these disorders. Stabilization or amelioration of cognitive outcomes represents a primary endpoint in many ongoing clinical trials for novel disease modifying treatments in this field. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Robot-induced hallucinations in Parkinson's disease depend on altered sensorimotor processing in fronto-temporal network

Hallucinations in Parkinson's disease (PD) are disturbing and frequent non-motor symptoms and constitute a major risk factor for psychosis and dementia. We report a robotics-based approach applying conflicting sensorimotor stimulation, enabling the induction of presence hallucinations (PHs) and the characterization of a subgroup of patients with PD with enhanced sensitivity for conflicting sensorimotor stimulation and robot-induced PH. We next identify the fronto-temporal network of PH by combining MR-compatible robotics (and sensorimotor stimulation in healthy participants) and lesion network mapping (neurological patients without PD). This PH-network was selectively disrupted in an additional and independent cohort of patients with PD, predicted the presence of symptomatic PH, and associated with cognitive decline. These robotics-neuroimaging findings extend existing sensorimotor hallucination models to PD and reveal the pathological cortical sensorimotor processes of PH in PD, potentially indicating a more severe form of PD that has been associated with psychosis and cognitive decline.

Risk factors for minor hallucinations in Parkinson's disease

OBJECTIVES

Minor hallucinations (MHs), including sense of presence, passage hallucinations, and visual illusions, have been reported in Parkinson's disease (PD). Here, we investigated the prevalence and associated risk factors for MHs according to appearance time.

METHODS

Data on the clinical characteristics and the appearance time of MHs for 100 PD patients were collected using a questionnaire and analyzed. MHs were classified into two groups according to the time when MHs appeared: MHs appearing while awake during the daytime (dMHs) and MHs appearing at arousal from sleep during the night or early morning (aMHs).

RESULTS

Thirty-eight patients (38%) experienced MHs. dMHs and aMHs were present in 21 (21%) and 28 patients (28%), respectively. Compared to patients without MHs, patients with dMHs had more severe motor symptoms, longer disease duration, higher levodopa equivalent daily dose (LEDD), and higher rates of cognitive impairment and visual hallucinations during the daytime, whereas patients with aMHs had a higher rate of rapid eye movement sleep behavior disorder (RBD), longer disease duration, higher LEDD, and higher dopamine agonist dosage. Logistic regression analysis showed that cognitive impairment was significantly associated with dMHs (odds ratio (OR) 7.292, p = .001), and that RBD (OR 8.306, p < .001) and LEDD (OR 1.002, p = .049) were significantly associated with aMHs.

CONCLUSIONS

Patients with MHs have different clinical characteristics according to the time when MHs appear. These findings have important clinical and prognostic implications and suggest appropriate therapeutic options for psychotic symptoms.

Premotor and fronto-striatal mechanisms associated with presence hallucinations in dementia with Lewy bodies

INTRODUCTION

presence hallucinations (PH) are frequent in dementia with Lewy bodies (DLB), but their cortico-subcortical origin is unknown. Recent studies have defined key frontal and temporal areas contributing to the occurrence of PH (PH-network) and tested their relevance in subjects with Parkinson's disease (PD). With the present study, we aimed at disentangling the metabolic and dopaminergic correlates of pH as well as their relation to a recently defined PH brain network in DLB.

METHODS

for the present study, we included 34 DLB subjects (10 with PH (PH + ); 24 without PH (PH-)), who underwent ¹⁸F-FDG PET and ¹²³I-FP-CIT SPECT imaging. We performed ¹⁸F-FDG PET group comparisons, as well as interregional correlation analyses using ¹⁸F-FDG PH-network regions as a seed.

RESULTS

PH + versus PH- had reduced ¹⁸F-FDG uptake in precentral, superior frontal and parietal gyri, involving ventral premotor cortex (vPMC) of the PH-network that showed strongly reduced functional connectivity with bilateral cortical regions. ¹⁸F-FDG vPMC uptake was negatively correlated with caudate ¹²³I-FP-CIT uptake in PH+ (p = 0.028) and interregional correlation analysis seeding from the vPMC showed widespread fronto-parietal ¹⁸F-FDG decreases in PH + .

DISCUSSION

these findings uncover the pivotal role of vPMC (involved in a PH-network) and its cortico-striatal connections in association with PH in DLB, improving our understanding of psychosis in neurodegeneration.

Illusions, hallucinations, and visual snow

Illusions and hallucinations are commonly encountered in both daily life and clinical practice. In this chapter, we review definitions and possible underlying mechanisms of these phenomena and then review what is known about specific conditions that are associated with them, including ophthalmic causes, migraine, epilepsy, Parkinson's disease, and schizophrenia. We then discuss specific syndromes including the Charles Bonnet syndrome, visual snow syndrome, Alice in Wonderland syndrome, and peduncular hallucinosis. The scientific study of illusions and hallucinations has contributed significantly to our understanding of how eye and brain process vision and contribute to perception. Important concepts are the distinction between topologic and hodologic mechanisms underlying hallucinations and the involvement of attentional networks. This chapter examines the various ways in which pathological illusions and hallucinations might arise in relation to the phenomenology and known pathology of the various conditions associated with them.

Altered awareness of cognitive and neuropsychiatric symptoms in Parkinson's disease and Dementia with Lewy Bodies: A systematic review

OBJECTIVES

Altered awareness of cognitive and neuropsychiatric symptoms is a common feature of neurodegeneration, which can significantly impact on quality of life, medication concordance and personal safety. Elucidating how awareness is affected by common alpha-synucleinopathies therefore has significant clinical relevance. We performed a systematic review of the literature on awareness of cognitive and neuropsychiatric symptoms in Parkinson's disease and Dementia with Lewy Bodies.

METHODS

Searches of PubMed and Web of Science were carried out, using keywords and MeSH subheadings, limited to papers in English dealing with humans. The terms "Parkinson's" or "Lewy body" were used to denote the disease of interest, combined with either "agnosia", "anosognosia", "insight", "metacognition", or "neuropsychology" to denote the neuropsychological area of interest.

RESULTS

21 publications investigating awareness of cognitive symptoms, and 18 publications on awareness of neuropsychiatric symptoms were identified. The large majority focused on Parkinson's disease rather than Dementia with Lewy Bodies. Cognitively intact people with Parkinson's disease may over-report cognitive symptoms, whilst those with cognitive impairment under-report symptoms. Awareness of neuropsychiatric symptoms is likely to decline over time, particularly in those with progressive cognitive impairment.

CONCLUSIONS

Altered awareness of cognitive and neuropsychiatric symptoms is common in Parkinson's disease. Symptom awareness varies significantly between individuals, and appears to be influenced by mood and global cognitive functioning, with executive functioning specifically implicated. There are gaps in our understanding of how dopaminergic medications influence symptom awareness, and a need for longitudinal studies of how awareness changes over time in Parkinson's disease and Dementia with Lewy Bodies.

Increasing Contrast Improves Object Perception in Parkinson's Disease with Visual Hallucinations

Background

Deficits in basic vision are associated with visual hallucinations in Parkinson's disease. Of particular interest is contrast sensitivity loss in this disorder and its effect on object identification.

Objectives

Evaluate whether increased contrast improves object perception in persons with Parkinson's disease and visual hallucinations, without dementia.

Methods

We assessed 26 individuals with mild to moderate idiopathic Parkinson's disease, half of whom reported one or more episodes of hallucinations/unusual perceptual experiences in the past month, with a letter-identification task that determined the contrast level required to achieve 80% accuracy. Contrast sensitivity was further assessed with a chart that presented stimuli at multiple spatial frequencies. The groups were closely matched for demographic and clinical characteristics except for experience of hallucinations.

Results

Relative to participants without visual hallucinations, those with hallucinations had poorer spatial frequency contrast sensitivity and required significantly greater contrast to correctly identify the letters on the identification task. Specifically, participants with hallucinations required a mean contrast of 52.8%, whereas participants without hallucinations required 35.0%. When given sufficient contrast, the groups with and without hallucinations were equally accurate in letter identification.

Conclusions

Compared to those without hallucinations, individuals with Parkinson's disease and hallucinations without dementia showed poorer contrast sensitivity. Once contrast was individually enhanced, the groups were equally accurate at object identification. These findings suggest the potential of visual perception tests to predict, and perception-based interventions to reduce, hallucinations in Parkinson's disease.

Hallucinations and other psychotic experiences across diagnoses: A comparison of phenomenological features

Although psychotic experiences are prevalent across many psychiatric, neurological, and medical disorders, investigation of these symptoms has largely been restricted to diagnostic categories. This study aims to examine phenomenological similarities and differences across a range of diagnoses. We assessed frequency, severity and phenomenology of psychotic experiences in 350 outpatients including; participants with schizophrenia spectrum disorders, hearing impairment, Parkinson's disease, Lewy Body Dementia, Alzheimer's disease, visual impairment, posttraumatic stress disorder, borderline personality disorder, and participants with recent major surgery. Psychotic phenomena were explored between these groups using the Questionnaire for Psychotic Experiences (QPE). Participants with major psychiatric disorders reported a combination of several psychotic experiences, and more severe experiences compared to all other disorders. Participants with recent major surgery or visual impairment experienced isolated visual hallucinations. Participants with hearing impairment reported isolated auditory hallucinations, whereas the neurodegenerative disorders reported visual hallucinations, occasionally in combination with hallucinations in another modality or delusions. The phenomenology between neurodegenerative disorders, and within major psychiatric disorders showed many similarities. Our findings indicate that the phenomenology of psychotic experiences is not diagnosis specific, but may rather point to the existence of various subtypes across diagnoses. These subtypes could have a different underlying etiology requiring specific treatment.

Presence phenomena in parkinsonian disorders: Phenomenology and neuropsychological correlates

INTRODUCTION

The feeling of a presence that occurs in the absence of objectively identifiable stimuli is common in parkinsonian disorders. Although previously considered benign and insignificant, recent evidence suggests that presence phenomena may act as the gateway to more severe hallucinations and dementia. Despite this, we still know relatively little about these phenomena.

OBJECTIVE

To examine parkinsonian disorder patients' subjective experience of presence phenomena, and retrospectively analyse their cognitive correlates, in order to elucidate the emergence of information processing deficits in parkinsonian disorders.

METHODS/DESIGN

25 patients who endorsed presence phenomena were asked to complete a semi-structured interview about their experiences. The cognitive profiles of these patients were then compared to those of age- and education-matched patients who denied presence phenomena.

RESULTS

Patients described the presence as mostly that of an unknown human with neutral valence. Patients who described it as unpleasant were noted to also demonstrate elevated anxiety. Patients who identified the presence as a known person, described it as touching them, or interacted with the presence emotionally or physically demonstrated reduced insight. Patients with presence phenomena demonstrated more frequent impairments in visual processing, executive function and speed of processing.

CONCLUSIONS

Presence phenomena occur in the company of advancing cognitive impairment and involvement of the posterior cortical functions. Initially encountered as a neutral spatial skeleton, the experience is then shaped by the patient's affective state and level of insight.

Sleeping disorders in children

In children with sensorimotor dysfunction (SMD), a history of sleeping disorder can be regularly recorded. Many children describe the following sleeping disorders: they need light or at least an open door. Additionally, a parent is needed. They often use soft toys, which are built around them like a wall in order to have close physical contact. In the dark they are afraid because they feel ghosts, a presence or simply a monster under the bed or in the room. Sensorimotor dysfunction (SMD) is a functional disorder of the movement system caused by reversible segmental dysfunctions, mostly in several sensory regions. The SMD is manifested not only through gross and fine motor weaknesses but also through behavioral problems. The SMD is diagnosed using the motocybernetic test (MCT). The symptom of behavioral sleeping disorder is highlighted, especially since it is a general problem both in healthy children and in children with behavioral problems, such as SMD, attention deficit hyperactivity disorder (ADHD) or autism spectrum disorders (ASD). As a therapeutic alternative, the possibilities of manual medicine are emphasized, especially atlas therapy according to Arlen, since the complaints will disappear completely after just a few treatment sessions.

Minor hallucinations in Parkinson disease: A subtle symptom with major clinical implications

OBJECTIVE

Psychosis is one of the most debilitating complications of Parkinson disease (PD). Although research on PD psychosis has been focused on the study of well-structured visual hallucinations (VH), currently accepted National Institute of Neurological Disorders and Stroke-National Institute of Mental Health diagnostic criteria emphasize minor hallucinations (MH) as the most common psychotic phenomena in PD. The objective of this review is to comprehensively describe the clinical and research advances on the understanding of MH and to provide future directions for obtaining further insights into their potential major implications for PD management and prognosis.

METHODS

A PubMed search was done in November 2018 to identify articles on minor psychotic phenomena in PD.

RESULTS

MH often precede the onset of well-structured VH and are associated with other nonmotor symptoms such as REM sleep behavior disorder and depression. The pattern of functional brain connectivity changes associated with MH involve visual-processing areas and attention control networks, which overlap with abnormalities described in patients with well-structured VH. The dysfunction of cortical networks in patients with MH may be an early indicator of a more widespread form of the disease.

CONCLUSION

Although called "minor," MH may have major clinical and prognostic implications. Further research is needed to establish whether MH are associated with a higher risk of disabling psychotic complications, cognitive deterioration, or a more accelerated disease progression. Understanding the early neurobiological underpinnings of MH may provide the background for future studies to identify the progressive dysfunction of neural circuits leading to more severe forms of psychosis in PD.

Pimavanserin in Parkinson's Disease-induced Psychosis: A Literature Review

Pimavanserin was approved for treating Parkinson’s disease (PD) psychosis, based upon 21 completed studies. This review article is to understand PD psychosis and assess the efficacy and safety of pimavanserin. A literature search was carried out using the keyword “pimavanserin” and cross-referencing it with PD, psychosis, efficacy, safety and clinical trial. Participants in pimavanserin group were associated with a 5.79-point decrease in symptoms for PD psychosis (SAPS-PD) scale compared to the 2.73-point decrease seen in the placebo group (P < .001). There were statistically significant improvements in the persecutory delusions, ideas of reference, and global ratings of delusions in pimavanserin group. Pimavanserin was well tolerated with no significant adverse events or worsening of motor function. Pimavanserin at 34 mg daily was shown to be effective for PD-induced psychosis in past clinical trials.

Feeling of presence in dementia with Lewy bodies is related to reduced left frontoparietal metabolism

Feeling of presence (FOP) refers to the vivid sensation of a person’s presence near oneself and is common in Dementia with Lewy Bodies (DLB). Based on previous observations on epileptic subjects, we hypothesized that DLB subjects with FOP would harbour ¹⁸F-fluorodeoxyglucose PET hypometabolism in left parietal areas. 25 subjects (mean age 71.9 ± 6.7, disease duration at scan 1.7 ± 1.5 years) were included in the study, of whom nine (36%) experienced FOP. No significant between-group difference was observed regarding dopamine transporters striatal uptake (p = 0.64), daily dopaminergic treatment dosage (p = 0.88) and visual hallucinations (p = 0.83). Statistical parametric mapping showed that subjects with FOP had a significantly reduced glucose metabolism in several left frontoparietal areas (p < 0.001), including superior parietal lobule and precuneus. Interregional correlation analysis of these areas showed specific connectivity with right insula and putamen in the FOP subgroup and right orbitofrontal and superior frontal in subjects without FOP. This provides further evidence about the role of a left frontoparietal network and suggest a possible contribution of impaired orbitofrontal reality filtering associated with FOP.

Negative mood invites psychotic false perception in dementia

Background

There is increasing evidence for predictive coding theories of psychosis, which state that hallucinations arise from abnormal perceptual priors or biases. However, psychological processes that foster abnormal priors/biases in patients suffering hallucinations have been largely unexplored. The widely recognized relationship between affective disorders and psychosis suggests a role for mood and emotion.

Methods

Thirty-six patients with dementia with Lewy bodies (DLB), a representative condition associated with psychosis of neurological origin, and 12 patients with Alzheimer’s disease (AD) were enrolled. After an experimental mood induction, the participants underwent the pareidolia test, in which visual hallucination-like illusions were evoked and measured.

Results

In DLB patients, the number of pareidolic illusions was doubled under negative mood compared to that under neutral mood. In AD patients, there was no significant difference in the number of pareidolic responses between negative and neutral mood conditions. A signal detection theory analysis demonstrated that the observed affective modulation of pareidolic illusions was mediated through heightened perceptual bias, not sensory deterioration.

Conclusions

The current findings demonstrated that abnormal perceptual priors in psychotic false perception have an affective nature, which we suggest are a type of cognitive feeling that arises in association with perception and cognition.

Uncommon and/or bizarre features of dementia: Part III

Clinical neurologists have long recognized that dementia can present as atypical or variant syndromes/symptoms. This study aimed at describing uncommon or bizarre symptoms/syndromes observed in patients suffering from dementia. Medline and Google scholar searches were conducted for relevant articles, chapters, and books published before 2018. Search terms used included compulsion, dementia, extracampine hallucination, disordered gambling, humour, and obsession. Publications found through this indexed search were reviewed for further relevant references. The uncommon/bizarre feature of dementia was described as case reports and there were no systematic investigations.

[Neuropsychiatry Of Movement Disorders]

Movement disorders can be defined as neurological syndromes presenting with excessive or diminished automatic or voluntary movements not related to weakness or spasticity. Both Parkinson's disease (PD) and Huntington's disease (HD) are well-known examples of these syndromes. The high prevalence of comorbid psychiatric symptoms like depression, anxiety, obsessive-compulsive symptoms, hallucinations, delusions, impulsivity, sleep disorders, apathy and cognitive impairment mean that these conditions must be regarded as neuropsychiatric diseases. In this article, we review neuroanatomical (structural and functional), psychopathological and neuropsychological aspects of PD and HD. The role of fronto-subcortical loops in non-motor functions is particularly emphasised in order to understand the clinical spectrum of both diseases, together with the influence of genetic, psychological and psychosocial aspects. A brief description of the main psychopharmacological approaches for both diseases is also included.

Psychosis in Parkinson Disease: A Review of Etiology, Phenomenology, and Management

Parkinson disease psychosis (PDP) is a common phenomenon in Parkinson disease (PD) patients treated with dopaminergic drugs, and is associated with high morbidity and mortality. It also correlates with depression and dementia, and can contribute to considerable caregiver stress and burnout. While symptoms can be relieved by decreasing doses or number of anti-PD medications, this may lead to an unacceptable worsening of motor function. When general medical or psychiatric conditions have been ruled out, and decreasing dopaminergic agents is not effective in treating psychosis, therapies include atypical antipsychotics, primarily clozapine and quetiapine. Of these, clozapine is effective but is associated with a poor side-effect profile and the necessity for frequent blood draws. Clinicians prefer quetiapine for its theoretically better safety profile, although there is no evidence for efficacy in treating psychosis. All atypical antipsychotics are associated with increased mortality in this patient population. Cholinesterase inhibitors can ameliorate psychosis symptoms. The serotonin 5-HT_2A receptor inverse agonist pimavanserin was recently approved by the US FDA for the treatment of PDP and may prove to be a more targeted therapy without the downsides of atypical antipsychotics.

The Structure and Measurement of Unusual Sensory Experiences in Different Modalities: The Multi-Modality Unusual Sensory Experiences Questionnaire (MUSEQ)

Hallucinations and other unusual sensory experiences (USE) can occur in all modalities in the general population. Yet, the existing literature is dominated by investigations into auditory hallucinations (“voices”), while other modalities remain under-researched. Furthermore, there is a paucity of measures which can systematically assess different modalities, which limits our ability to detect individual and group differences across modalities. The current study explored such differences using a new scale, the Multi-Modality Unusual Sensory Experiences Questionnaire (MUSEQ). The MUSEQ is a 43-item self-report measure which assesses USE in six modalities: auditory, visual, olfactory, gustatory, bodily sensations, and sensed presence. Scale development and validation involved a total of 1,300 participants, which included: 513 students and community members for initial development, 32 individuals with schizophrenia spectrum disorder or bipolar disorder for validation, 659 students for factor replication, and 96 students for test-retest reliability. Confirmatory factor analyses showed that a correlated-factors model and bifactor model yielded acceptable model fit, while a unidimensional model fitted poorly. These findings were confirmed in the replication sample. Results showed contributions from a general common factor, as well as modality-specific factors. The latter accounted for less variance than the general factor, but could still detect theoretically meaningful group differences. The MUSEQ showed good reliability, construct validity, and could discriminate non-clinical and clinical groups. The MUSEQ offers a reliable means of measuring hallucinations and other USE in six different modalities.

Psychosis in Parkinson's Disease: Epidemiology, Pathophysiology, and Management

Psychotic symptoms are common in Parkinson's disease (PD) and are associated with poorer quality of life and increased caregiver burden. PD psychosis is correlated with several factors, such as more advanced disease, cognitive impairment, depression, and sleep disorders. The underlying causes of psychosis in PD thus involve a complex interplay between exogenous (e.g., drugs, intercurrent illnesses) and endogenous (e.g., PD disease pathology) factors. Current theories of the pathophysiology of PD psychosis have come from several neuropathological and neuroimaging studies that implicate pathways involving visual processing and executive function, including temporo-limbic structures and neocortical gray matter with altered neurotransmitter functioning (e.g., dopamine, serotonin, and acetylcholine). Treatment of PD psychosis requires a step-wise process, including initial careful investigation of treatable triggering conditions and a comprehensive evaluation with adjustment of PD medications and/or initiation of specific antipsychotic therapies. Clozapine remains the only recommended drug for the treatment of PD psychosis; however, because of regular blood monitoring, quetiapine is usually first-line therapy, although less efficacious. Emerging studies have focused on agents involving other neurotransmitters, including the serotonin 5-HT2A receptor inverse agonist pimavanserin, cholinesterase inhibitors, and antidepressants and anxiolytics.