Perceptual Aberration Research Articles

Schizotypy 17 years on: Prediction of schizotypic individual differences in midlife.

The picture for the long-term prediction of schizotypic individual difference features in relation to schizotypy assessed earlier in life remains opaque. Whereas schizotypy assessed earlier in life, typically during the late teen years, has been shown to predict nonaffective psychotic illness as well as the presence of nonaffective psychotic features (Chapman et al., 1994; Lenzenweger, 2021), the presence in midlife (mid-30s) of nonpsychotic schizotypic features in those assessed for schizotypy earlier in life remains to be demonstrated. The current study, which reports on a 17-year follow-up study, addresses this void in the schizotypy literature. Seventeen years after an initial psychometric assessment for schizotypy, in a sample of emerging adults (age = 18) with no prior history of psychotic illness, Perceptual Aberration Scale scores predicted elevated schizotypal personality features, increased schizophrenia-related personality disorder features (particularly schizotypal and paranoid), and elevated schizophrenia proneness scores at age 35. This pattern of associations was maintained even after the removal of participants with a diagnosis of nonaffective psychosis. The associations also remained largely unchanged net of state anxiety levels at initial and later assessments. These results support the emergence or maintenance of schizotypic psychopathology features consistent with a model that views schizotypy as the underlying liability for schizotypic psychopathology phenotypes. The results also provide additional support for both the construct validity of the initial psychometric schizotypy measure (Perceptual Aberration Scale) as well as the validity of the psychometric high-risk paradigm. Longitudinal research remains an illuminating and informative approach to understanding the nature of schizophrenia-related psychopathology by utilizing time as an essential scientific lever. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Exploring the effects of family and life events on genetic and environmental architecture of schizotypal and hypomanic dimensions: Insights from a twin study

BackgroundStrategies of prevention for psychiatric disorders need a deep understanding of the aetiological factors involved in the psychopathological processes. Our twin study aims at disentangling the contributions of genes and environment to schizotypal and hypomanic dimensions, considering the role of stressful life events (LEs) and the quality of family relationships. MethodsThe Magical Ideation Scale (MIS) and Perceptual Aberration Scale (PAS) were used to assess positive schizotypy, while Hypomanic Personality Scale (HPS) and its sub-scales were used to investigate proneness to affective disorders. 268 twins (54.5 % female; aged 18.0 ± 6.68) were included. Participants filled out a questionnaire on LEs and their parents provided an evaluation of intra-family relationship (Relationship Quality Index, RQI). Classic univariate twin models for quantitative traits were fitted for scales, and the effects of covariates (LEs and RQI) were assessed. ResultsFor MIS, HPS and its sub-scales, significant common and unique environmental effects were detected, with genetic factors affecting only HPS Social Vitality sub-scale. Unique environment was the only source of variance of PAS score. The number of recent LEs influenced MIS and PAS models, while RQI score affected MIS model. LimitationsThe main limitation of the study is the small sample size, which reduces statistical power and may potentially lead to an underestimation of heritability. Additionally, the cross-sectional design limits the possibility to draw causal considerations. ConclusionsFindings provide preliminary evidence for a significant environmental role in modulating states of vulnerability. Moreover, the expression of positive schizotypy resulted influenced by recent stressors and intra-family relationships.

Investigating sensitivity to multi-domain prediction errors in chronic auditory phantom perception

The perception of a continuous phantom in a sensory domain in the absence of an external stimulus is explained as a maladaptive compensation of aberrant predictive coding, a proposed unified theory of brain functioning. If this were true, these changes would occur not only in the domain of the phantom percept but in other sensory domains as well. We confirm this hypothesis by using tinnitus (continuous phantom sound) as a model and probe the predictive coding mechanism using the established local–global oddball paradigm in both the auditory and visual domains. We observe that tinnitus patients are sensitive to changes in predictive coding not only in the auditory but also in the visual domain. We report changes in well-established components of event-related EEG such as the mismatch negativity. Furthermore, deviations in stimulus characteristics were correlated with the subjective tinnitus distress. These results provide an empirical confirmation that aberrant perceptions are a symptom of a higher-order systemic disorder transcending the domain of the percept.

Interplay between childhood trauma, bodily self-disturbances, and clinical phenomena in schizophrenia spectrum disorders: A network analysis

BackgroundBodily self-disturbances have long been considered central to schizophrenia. Exposure to childhood trauma has been linked to the development of both psychosis and bodily self-disturbances, yet little work has examined the role of bodily self-disturbances in the relationship between childhood trauma and schizophrenia symptomatology. This study uses network analysis to bridge this gap. MethodsNetworks were constructed to examine relationships between schizophrenia symptoms (Positive and Negative Symptom Scale; PANSS), bodily self-disturbances (Perceptual Aberration Scale; PAS), and self-reported exposure to childhood trauma (Childhood Trauma Questionnaire, Short-Form; CTQ-SF) in 152 people with a schizophrenia-spectrum disorder. Shortest path and bridge analyses were conducted to assess the role of bodily self-disturbances in linking childhood trauma to schizophrenia symptomatology. Three networks were constructed: 1) PAS, childhood trauma, and PANSS sub-scale composites (positive, negative, general); 2) PAS, childhood trauma, and positive symptoms, 3) PAS, childhood trauma, and distress symptoms. ResultsShortest path analysis revealed that bodily self-disturbances were on the shortest path between childhood trauma and positive and general symptoms (Network 1), between trauma and hallucinations (Network 2), and between trauma and depression (Network 3). Bodily self-disturbances were also found to serve as a bridge between childhood trauma and positive symptoms of schizophrenia, particularly delusions and hallucinations. ConclusionsUsing a novel, data-driven approach, we showed that bodily self-disturbances play a key role in linking childhood trauma to positive and co-morbid affective symptoms of schizophrenia. Threat experiences (i.e., abuse) specifically relate to bodily self-disturbances and psychotic symptoms.

Network Structure of Childhood Trauma, Bodily Disturbances, and Schizotypy in Schizophrenia and Nonclinical Controls.

Exposure to childhood trauma has been linked to the development of psychosis and bodily self-disturbances, 2 hallmarks of schizophrenia (SZ). Prior work demonstrated that bodily disturbances serve as a bridge between childhood trauma and SZ symptomatology, but the diagnostic specificity of these connections remains unknown. This study uses network analysis to bridge this gap by comparing the interplays between childhood trauma, bodily self-disturbances, and schizotypy in clinical and general populations. Networks were constructed to examine the relationships between schizotypy (Schizotypal Personality Questionnaire; SPQ), bodily self-disturbances (Perceptual Aberration Scale; PAS), and childhood trauma (Childhood Trauma Questionnaire, CTQ) in 152 people with SZ and 162 healthy comparison participants (HC). The Fused Graphical Lasso was used to jointly estimate the networks in the 2 groups and the structure and strength of the networks were compared. Node centrality and shortest paths between CTQ, PAS, and schizotypy were examined. When comparing SZ and HC, the network of bodily self-disturbances, childhood trauma, and schizotypy were similarly structured, but the network was significantly stronger in SZ than HC. In both groups, bodily self-disturbances were on one of the shortest paths between childhood trauma to schizotypal experiences. Our findings revealed reliable associations between childhood trauma, bodily self-disturbance, and schizotypy, with bodily disturbances acting as a bridge from childhood trauma to schizotypy. The elevated strength of the SZ network indicates a more highly interconnected, and therefore reactive network in which exposure to childhood trauma can more easily activate bodily disturbances and schizotypy.

Optimised Multi-Channel Transcranial Direct Current Stimulation (MtDCS) Reveals Differential Involvement of the Right-Ventrolateral Prefrontal Cortex (rVLPFC) and Insular Complex in those Predisposed to Aberrant Experiences

Research has shown a prominent role for cortical hyperexcitability underlying aberrant perceptions, hallucinations, and distortions in human conscious experience – even in neurotypical groups. The rVLPFC has been identified as an important structure in mediating cognitive affective states / feeling conscious states. The current study examined the involvement of the rVLPFC in mediating cognitive affective states in those predisposed to aberrant experiences in the neurotypical population. Participants completed two trait-based measures: (i) the Cortical Hyperexcitability Index_II (CHi_II, a proxy measure of cortical hyperexcitability) and (ii) two factors from the Cambridge Depersonalisation Scale (CDS). An optimised 7-channel MtDCS montage for stimulation conditions (Anodal, Cathodal and Sham) was created targeting the rVLPFC in a single-blind study. At the end of each stimulation session, participants completed a body-threat task (BTAB) while skin conductance responses (SCRs) and psychological responses were recorded. Participants with signs of increasing cortical hyperexcitability showed significant suppression of SCRs in the Cathodal stimulation relative to the Anodal and sSham conditions. Those high on the trait-based measures of depersonalisation-like experiences failed to show reliable effects. Collectively, the findings suggest that baseline brain states can mediate the effects of neurostimulation which would be missed via sample level averaging and without appropriate measures for stratifying individual differences.

Bridging phenomenology and neural mechanisms of inner speech: ALE meta-analysis on egocentricity and spontaneity in a dual-mechanistic framework

The neural mechanisms of inner speech remain unclear despite its importance in a variety of cognitive processes and its implication in aberrant perceptions such as auditory verbal hallucinations. Previous research has proposed a corollary discharge model in which inner speech is a truncated form of overt speech, relying on speech production-related regions (e.g. left inferior frontal gyrus). This model does not fully capture the diverse phenomenology of inner speech and recent research suggesting alternative perception-related mechanisms of generation. Therefore, we present and test a framework in which inner speech can be generated by two separate mechanisms, depending on its phenomenological qualities: a corollary discharge mechanism relying on speech production regions and a perceptual simulation mechanism within speech perceptual regions. The results of the activation likelihood estimation meta-analysis examining inner speech studies support the idea that varieties of inner speech recruit different neural mechanisms.

An examination of the relationship between positive schizotypy and suicide risk using five distinct samples.

Individuals with schizophrenia are at increased risk for suicide. However, much less is known about suicide risk among individuals with schizotypic features. To address this gap in the literature, the current report examines the relationship between positive schizotypy and suicide risk using five distinct samples. Each of these five studies addresses unique, but complementary, questions regarding the relationship between positive schizotypy and suicide risk. Studies 1 and 2 investigate the cross-sectional relationship between perceptual aberrations and suicidal ideation. Study 3 examines the relationship between suicidal ideation and multiple positive schizotypic features (perceptual aberrations, magical thinking, paranoia, and referential thinking). Study 4 investigates the long-term relationship between perceptual aberrations and suicide risk through a 17-year follow-up. Finally, Study 5 examines the specificity of our findings using a psychiatric control group. Results across all five studies support a relationship between suicide risk and positive schizotypy. Specifically, perceptual aberrations were associated with suicide risk both cross-sectionally and longitudinally. Results also suggest that individuals with positive schizotypic features have rates of suicidal ideation that are comparable to those with high negative affect and are significantly greater than healthy controls. Taken together, these findings establish an empirical connection between positive schizotypy and suicide risk, thus expanding the purview of the suicide risk construct. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Brief rapport: Perceptual aberration in patients at ultra-high risk for psychosis.

Ultra-high risk (UHR) is considered a forerunner of psychosis, but most UHR individuals do not later convert, yet remain symptomatic, disabled and help-seeking. Thus, there is an increased recognition of the UHR phenotype as a syndrome in itself, rather than merely a risk syndrome. It is therefore essential to investigate outcomes other than transition to psychosis. For this purpose, perceptual aberration appears to be a distinct, as well as a stable and less state-specific vulnerability indicator. We aimed to investigate perceptual aberration and associations with functional, neuro and social cognitive risk factors in an UHR sample. One hundred and twenty UHR and 64 healthy controls were compared on levels of perceptual aberration using the perceptual aberration scale. We further investigated cross-sectional associations between perceptual aberration and CAARMS (as a measure of subthreshold psychotic symptoms) and functional, neuro and social cognitive risk factors within the UHR using Spearmans ρ. Perceptual aberration was significantly higher in UHR than in healthy controls and was associated with social functioning, executive functioning, and emotion recognition. Our findings are consistent with a view of perceptual aberration as a stable vulnerability indicator that varies little with clinical state.

Proprioception and Tactile Perception in Schizophrenia

The aim of this review is to investigate the relationship between proprioceptive and tactile perceptual aberrations and the psychotic symptoms of schizophrenia, a correlation which has already been established by several studies (Lenzenweger, 2006; Postmes et al., 2014; Chang and Lenzenweger, 2005; Michael and Park, 2016; Germine et al., 2013; Kent et al., 2010). However, the direction of causality within the correlation is still unknown. Because several studies indicate an abnormal and uneven weighting of the senses in schizophrenic multisensory integration, it is possible that the psychotic symptoms of schizophrenia may be due to multisensory integration abnormalities involving proprioceptive and tactile perception. Several theories have also been proposed that schizophrenia itself is the cause of these proprioceptive and tactile perception anomalies. There could also be neuroanatomical factors that underlie both the schizophrenia psychotic symptoms and proprioceptive and tactile perception aberrations. Because of limitations in the current research, a definite causal direction is still unable to be determined. Several practices to improve the methods of analysis in this field of study include incorporating measures of schizotypy with less subjectivity and using longitudinal neurodevelopmental studies to pinpoint developmental aberrations in proprioception, tactile perception, and the correlated psychotic symptoms of schizophrenia. These methods may lead to better pre-emptive target interventions and could establish the directionality of causation between proprioception and tactile perception anomalies and positive schizophrenia symptoms.

The Role of Shame in Schizophrenia Delusion: The Interplay Between Cognitive-Perceptual and Emotional Traits.

Through a strictly dimensional approach, the present study aimed at evaluating the interplay between cognitive-perceptual disturbances and emotional dispositions, particularly shame proneness, in schizophrenia delusion. One hundred one outpatients with schizophrenia were administered the Peters et al. Delusions Inventory, the Referential Thinking Scale (REF), the Magical Ideation Scale (MIS), the Perceptual Aberration Scale (PAS), the Positive and Negative Affect Schedule and the Experiences of Shame Scale (ESS). The severity of delusional ideation was positively related to all the cognitive-perceptual scales (REF, MIS, and PAS) and to shame proneness (ESS). Referential thinking (REF) emerged as the strongest predictor of delusion severity. The experience of shame played a mediation role in the relationship between cognitive-perceptual traits and delusional severity. These data suggest that severity delusion in schizophrenia depends, at least in part, on a complex interplay between cognitive-perceptual disturbances and experiences of shame.

Psychometric Properties of the Italian Version of the Embodied Sense-of-Self Scale.

(1) Background: The Embodied Sense-of-Self Scale (ESSS) is the only validated measure for self-assessing embodiment abnormalities, which differentiate people with anomalous embodied self-representations such as schizophrenic patients from controls. The aim of the current study was to translate the ESSS from English to Italian and to examine its factor structure, reliability, and validity in the Italian context. (2) Methods: We tested the fit of the original three-factor structure (agency, ownership, and narrative identity) across a community sample (N = 269) and the reliability as well as the convergent and divergent validity of the ESSS. (3) Results: The three-factor structure of the ESSS was confirmed. However, three different factors have emerged from our analysis (self-recognition, self-consistence, and self-awareness). Higher internal consistency of the ESSS was obtained by removing six items that seemed problematic. The three ESSS scales show highly intercorrelated constructs. The measure was reliable and positively correlated with schizotypy (via the Perceptual Aberration Scale) and aberrant salience (via the Aberrant Salience Inventory), and negatively correlated with empathy (via the Italian Short Empathy Quotient scale), generalized self-efficacy (via the Generalized Self-Efficacy Scale), and social self-efficacy (via the Perceived Social Self-Efficacy Scale). (4) Conclusions: The 19-item Italian version of the ESSS is a suitable measure with which to assess embodiment abnormalities in Italian samples.

Intersections of paranoia and the body in the general population.

Negative body image may be associated with heightened feelings of paranoia. The current study aimed to conduct multidimensional assessments of body image and psychosis facets in the general population. Respondents were 407 individuals, who provided basic sociodemographic information, and completed online questionnaires evaluating dysmorphic concerns, body consciousness, paranoia, persecutory and magical ideation and perceptual aberration. Correlation analysis and a series of regressions onto various body image facets (i.e. dysmorphic concerns, private body consciousness, public body consciousness and body competence) were conducted. Distinct patterns of significant associations were uncovered across the range of body image and psychosis facets examined. Paranoia significantly contributed to the severity of dysmorphic concerns, and magical ideation significantly contributed to private and public body consciousness, though effect sizes were modest. Our findings corroborate the relationship between paranoia and dysmorphic concerns, and tentatively suggest that challenging paranoid beliefs could be a useful strategy for managing negative body image.

Impaired sensitivity to spatial configurations in healthy aging

Healthy aging is associated with decline in social, emotion, and identity perception, which is frequently attributed to deterioration of structures involved in social inference. It is believed that this decline is unlikely to be a result of perceptual aberrations due to intact (corrected) visual acuity. Nevertheless, the present studies examine whether more particular perceptual aberrations may be present in healthy aging, that could in principle contribute to such difficulties. The present study examined the possibility that particular deficits in configural processing impair the perception of faces in healthy aging. Across two signal detection experiments, we required a group of healthy older adults and matched younger adults to detect changes in images of faces that could differ either at the local, featural level, or in configuration of these features. In support of our hypothesis, older adults were particularly impaired in detecting configural changes, relative to detecting changes in features. The impairments were found for both upright and inverted faces and were similar in a task with images of inanimate objects (houses). Drift diffusion modelling suggested that this decline related to reduced evidence accumulation rather than a tendency to make configural judgments based on less evidence. These findings indicate that domain-general problems processing configural information contribute to the difficulties with face processing in healthy aging, and may in principle contribute to a range of higher-level social difficulties – with implications also for other groups exhibiting similar patterns in perception and understanding.

Predictive and discriminant validity of different psychopathology and temperament scales for major psychiatric disorders – 23-year follow-up of the Northern Finland Birth Cohort 1966

Introduction Several psychological and psychiatric instruments have been developed to recognize or predict different psychiatric disorders.ObjectivesWe studied the predictive, and discriminant validity of different psychopathology scales and temperament traits for subsequent psychiatric diagnoses due to schizophrenia, bipolar and depressive disorders in a 23-year follow-up.MethodsTemperament traits, perceptual aberration, physical and social anhedonia, depression and anxiety subscales of Symptom Checklist (SCL-D and SCL-A), Hypomanic Personality Scale (HPS), Schizoidia Scale, and Bipolar II Scale were completed as part of the 31-year follow-up survey of the prospective Northern Finland 1966 Birth Cohort (n = 5006). New onset psychiatric diagnoses were followed until age of 54 years using different nationwide registers.Results In the follow-up 28 (0.6%) individuals had diagnosis of schizophrenia, 40 (0.8%) bipolar and 405 (8.1%) depressive disorders. Several of the included scales associated statistically significantly with subsequent diagnoses. High SCL-A and SCL-D scores were strong predictors (Cohen’s d’s between 0.76 and 1.08) for schizophrenia and depressive disorders, whereas high HPS score was best predictor (d=0.67) for bipolar disorders. When comparing patient groups, schizophrenia group had low scores in reward dependence when compared with both bipolar (d=-0.80) and depressive (d=-0.66) disorders. Harm avoidance was the best trait to discriminate depressive and bipolar disorders, with higher scores in depressive disorders (d=0.48).ConclusionsInterestingly we found that differed psychopathology scales were strong but non-specific predictors for these psychiatric disorders, whereas temperament traits were useful predictors regarding discriminating these disorders. The presented scales can be used in population samples when predicting psychiatric illnesses.DisclosureNo significant relationships.

The psychopathological trajectories to delusion in Schizophrenia: the affective and schizotypal pathways

IntroductionDelusions are a key feature of schizophrenia psychopathology. From a phenomenological approach, Jaspers (1913) differentiates between “primary” or true schizophrenic delusions, defined as an unmediated phenomenon that cannot be understood in terms of prior psychological origin or motivation, and “secondary” delusions, understandable from the patient’s mood state or personality. Primary delusions have been considered the hallmark of reality distorsion dimension in schizophrenia, disregarding a possible affective patwhay to delusional belief.ObjectivesThe present study was aimed at elucidating the psychopathological trajectories to delusion in schizophrenia through the investigation of both affective and schizotypal trait dispositions.MethodsSeventy-eight participants affected by schizophrenia were administered the Peters Delusional Inventory (PDI), the Positive and Negative Affective Scale (PANAS), the Experience of Shame Scale (ESS), the Referential Thinking Scale (REF), the Magical Ideation Scale (MIS) and the Perceptual Aberration Scale (PAS).ResultsThe severity of delusional ideation (PDI) was positively related to both affective (PANAS positive dimension, ESS) and schizotypal traits (MIS, PAS and REF). Moreover, referential thinking (REF) mediated the relationship between “magical ideation” (MIS) and delusions severity (Fig. 1), whereas experience of shame (ESS) was a moderating factor in the between referential thinking and delusion severity (Fig. 2).ConclusionsThe study findings suggest that in schizophrenia patients, severity of delusions is underpinned by an intertwining of both affective and schizotypal pathways.DisclosureNo significant relationships.

The stress-vulnerability model on the path to schizophrenia: Interaction between BDNF methylation and schizotypy on the resting-state brain network

The interplay between schizophrenia liability and environmental influences has been considered to be responsible for the development of schizophrenia. Recent neuroimaging studies have linked aberrant functional connectivity (FC) between the default-mode network (DMN) and the frontoparietal network (FPN) in the resting-state to the underlying neural mechanism of schizophrenia. By using schizotypy as the proxy for genetic-based liability to schizophrenia and methylation of brain-derived neurotrophic factor (BDNF) to represent environmental exposure, this study investigated the impact of the interaction between vulnerability and the environment on the neurobiological substrates of schizophrenia. Participants in this study included 101 healthy adults (HC) and 46 individuals with ultra-high risk for psychosis (UHR). All participants were tested at resting-state by functional magnetic resonance imaging, and group-independent component analysis was used to identify the DMN and the FPN. The Perceptual Aberration Scale (PAS) was used to evaluate the schizotypy level. The methylation status of BDNF was measured by pyrosequencing. For moderation analysis, the final sample consisted of 83 HC and 32 UHR individuals. UHR individuals showed reduced DMN-FPN network FC compared to healthy controls. PAS scores significantly moderated the relationship between the percentage of BDNF methylation and DMN-FPN network FC. The strength of the positive relationship between BDNF methylation and the network FC was reduced when the schizotypy level increased. These findings support the moderating role of schizotypy on the neurobiological mechanism of schizophrenia in conjunction with epigenetic changes.

P589. Psychotic Features Impact Perception Rather Than Learning

The nascent field of computational psychiatry has used the framework of Bayesian inference to explain psychosis and aberrant perceptions like hallucinations. Recent studies have proposed that psychosis is characterized by an abnormal relative weight of priors over sensory likelihood, but their conclusions are sometimes conflicting.

An Exploration of the Aberrant Perceptions Experienced by Westerners in the Peruvian Amazon Amid Shipibo Ayahuasca Practices

ABSTRACTAyahuasca has become a subject of great interest in recent years. Academics, spiritual seekers, communities, and curious individuals have all been intrigued by this topic through either writing about it or direct participation in the contemporary spiritual phenomenon that is ayahuasca, which holds promises of bestowing upon its users profound wisdom or healing. However, what anthropological (but also popular) writings barely comment on are the deviant perceptions that arise out of experiences seeking amelioration or transcendence, and the subjective ways in which those experiences are interpreted. Consequently, I wish to supplement this scope of representation. In this text, I present fieldwork conducted in the Peruvian Amazon amid the Shipibo, focusing on the experiences of the spiritual seekers who came to them in search of healing or self‐discovery. I discovered a unique contradiction—participation in Shipibo ayahuasca practices while simultaneously having or developing a negative perception or attitude towards it. These aberrances are held, as I argue herein, (incognizantly) in the expressed attitudes of the Westerners (especially North American and European) as a result of the positivist notions that emerged from the Age of Enlightenment (but are not limited to it). My priority in this article is to present and expound on these atypical associations and place them against a historical (Western) background to elucidate the origin of the thus found and experienced perceptions.

Delusions and hallucinations correlates in Parkinson's disease psychosis

<h3>Introduction</h3> Patients with Parkinson disease (PD) can experience hallucinations (spontaneous aberrant perceptions) and illusions (misinterpretations of real perceptual stimuli). Of such phenomena, visual hallucinations and illusions are the most frequently encountered, although auditory, olfactory and tactile hallucinations can also occur. Hallucinations can have substantial psychosocial effects and, historically, were the main reason for placing patients in nursing homes. Concomitant or overlapping mechanisms are probably active during visual hallucinations, and these include the following: central dopaminergic over-activity and an imbalance with cholinergic neurotransmission; dysfunction of the visual pathways, alterations of brainstem sleep-wake and dream regulation; and impaired attention focus.The aim of this is to present epidemiological, genetic and pathophysiological aspects of psychosis in PD. <h3>Methods</h3> Pacific Northwest Udall Center (PANUC) was analyzed. MOCA was used to assess cognition and the NPI to examine neuropsychological symptoms including psychosis. Patients with PD without hallucinations or delusions served as controls Comparing characteristics of the PD cohort according to having either no psychosis or delusions with or without hallucinations (using the 10-item Neuropsychiatric Inventory (NPI).Chi-square test was applied to compare categorical variables; Fisher's exact test was applied to compare categorical variables when cell frequency is less than 5. Categorical factors were presented as frequencies (percentages). Unavailable logistic regression models were employed to assess association between predictors and outcome.All tests was two-tailed and performed at a significance level of 0.05. R version 3.5.1 (The R Foundation for Statistical Computing, Vienna, Austria) was used for all analyses. <h3>Results</h3> 129 persons (11% of analyzed sample) were included to the study. Of the entire patient's who reported psychotic symptoms: (84%) experienced hallucinations without delusions, (36%) had symptoms dominated by delusions. Severity and/or number of hallucination subtypes were significantly correlated with lower scores in language, memory, attention, executive functioning, and visuospatial ability. Correlations with delusions were non-significant. Tests of differences in the size of the correlations between groups revealed a significant relationship between language and visuospatial performance with hallucinations. Results suggested a significant association between APOE4 status and hallucinations. Compared to APOE4 non-carrier, APOE carrier patients have 4.509 times of odds to develop hallucinations. <h3>Conclusions</h3> Genetic and cognitive correlates of hallucinations and delusions appear to be different in PD, suggesting distinct pathogenic mechanisms and possibly anatomical substrates. Hence, delusions may not share the same associations with dementia as hallucinations