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Behavioral Neuroscience Jun 2024In recent years, there have been significant advances in our understanding of the positive symptoms of schizophrenia, such as hallucinations and delusions. This progress... (Review)
Review
In recent years, there have been significant advances in our understanding of the positive symptoms of schizophrenia, such as hallucinations and delusions. This progress has been significantly aided by the use of associative learning-based approaches in human subjects and preclinical animal models. Here, we first review experimental research focusing on the abnormal processing of absent stimuli using three different conditioning phenomena: conditioned hallucinations, mediated conditioning, and trace conditioning. We then review studies investigating the ability to reduce focal processing of physically present but informationally redundant stimuli using habituation, latent inhibition, and blocking. The results of these different lines of research are then summarized within the framework of Wagner's (1981) standard operating procedures model, an associative learning model with explicit reference to the internal representations of both present and absent stimuli. Within this framework, the central deficit associated with positive symptoms can be described as a failure to suppress the focal processing of both absent stimuli and present but irrelevant stimuli. This can explain the wide range of results obtained in different experimental settings. Finally, we briefly discuss the role of the hippocampus and its interaction with dopaminergic transmission in the emergence of such abnormal stimulus representations and learning. Overall, we hope that the theoretical framework and empirical findings offered by the associative learning approach will continue to facilitate and integrate analyses of schizophrenia conducted at the psychological and behavioral levels on the one hand, and at the neural and molecular levels on the other, by serving as a useful interface between them. (PsycInfo Database Record (c) 2024 APA, all rights reserved).
Topics: Humans; Association Learning; Schizophrenia; Animals; Psychotic Disorders; Hallucinations; Schizophrenic Psychology; Conditioning, Classical; Hippocampus; Perception
PubMed: 38934921
DOI: 10.1037/bne0000599 -
Neuroscience and Biobehavioral Reviews Jun 2024The sense of agency is the experience of being the author of self-generated actions and their outcomes. Both clinical manifestations and experimental evidence suggest... (Review)
Review
The sense of agency is the experience of being the author of self-generated actions and their outcomes. Both clinical manifestations and experimental evidence suggest that the agency experience and the mechanisms underlying agency attribution may be dysfunctional in schizophrenia. Yet, studies investigating the sense of agency in these patients show seemingly conflicting results: some indicated under-attribution of self-agency (coherently with certain positive symptoms), while others suggested over-attribution of self-agency. In this review, we assess whether recent theoretical frameworks can reconcile these divergent results. We examine whether the identification of agency abnormalities in schizophrenia might depend on the measure of self-agency considered (depending on the specific task requirements) and the available agency-related cues. We conclude that all these aspects are relevant to predict and characterise the type of agency misattribution that schizophrenia patients might show. We argue that one particular model, based on the predictive coding theory, can reconcile the interpretation of the multifarious phenomenology of agency manifestations in schizophrenia, paving the way for testing agency disorders in novel ways.
PubMed: 38925210
DOI: 10.1016/j.neubiorev.2024.105781 -
Epilepsy & Behavior : E&B Jun 2024Psychotic manifestations are a classic feature of non-convulsive status epilepticus (NCSE) of temporal origin. For several decades now, the various psychiatric...
Psychotic manifestations are a classic feature of non-convulsive status epilepticus (NCSE) of temporal origin. For several decades now, the various psychiatric manifestations of NCSE have been described, and in particular, the diagnostic challenges they pose. However, studies using stereotactic-EEG (SEEG) recordings are very rare. Only a few cases have been reported, but they demonstrated the anatomical substrate of certain manifestations, including hallucinations, delusions, and emotional changes. The post-ictal origin of some of the manifestations should be emphasized. More generally, SEEG has shown that seizures affecting the temporal and frontal limbic systems can lead to intense emotional experiences and behavioural disturbances.
PubMed: 38924969
DOI: 10.1016/j.yebeh.2024.109911 -
Schizophrenia Research Jun 2024Schizophrenia continues its resistance to the pathogenetic understanding. We believe that one of the reasons is an oblivion of schizophrenia's characteristic Gestalt... (Review)
Review
Schizophrenia continues its resistance to the pathogenetic understanding. We believe that one of the reasons is an oblivion of schizophrenia's characteristic Gestalt expressive of its psychopathological structure. In this article we argue for a crucial role of disorders of selfhood in the constitution of this Gestalt. First, we present a phenomenological account of the self. This is followed by an exposition of basic complains in schizophrenia which are reflective of a disordered selfhood and which often date back to childhood. We then present characteristic features of the schizophrenic psychosis with its phenomenon of "double bookkeeping". Hallucinations, delusions and double bookkeeping are all associated with the instability of the self. Finally, we briefly address characteristic aspects of the encounter with a schizophrenia patient and argue that self-disorders play an important diagnostic role. We conclude by emphasizing the role of phenomenology in psychiatric research.
PubMed: 38924937
DOI: 10.1016/j.schres.2024.06.032 -
Psychophysiology Jun 2024Individuals diagnosed with schizophrenia (SZ) demonstrate difficulty distinguishing between internally and externally generated stimuli. These aberrations in "source...
Individuals diagnosed with schizophrenia (SZ) demonstrate difficulty distinguishing between internally and externally generated stimuli. These aberrations in "source monitoring" have been theorized as contributing to symptoms of the disorder, including hallucinations and delusions. Altered connectivity within the default mode network (DMN) of the brain has been proposed as a mechanism through which discrimination between self-generated and externally generated events is disrupted. Source monitoring abnormalities in SZ have additionally been linked to impairments in selective attention and inhibitory processing, which are reliably observed via the N100 component of the event-related brain potential elicited during an auditory paired-stimulus paradigm. Given overlapping constructs associated with DMN connectivity and N100 in SZ, the present investigation evaluated relationships between these measures of disorder-related dysfunction and sought to clarify the nature of task-based DMN function in SZ. DMN connectivity and N100 measures were assessed using EEG recorded from SZ during their first episode of illness (N = 52) and demographically matched healthy comparison participants (N = 25). SZ demonstrated less evoked theta-band connectivity within DMN following presentation of pairs of identical auditory stimuli than HC. Greater DMN connectivity among SZ was associated with better performance on measures of sustained attention (p = .03) and working memory (p = .09), as well as lower severity of negative symptoms, though it was not predictive of N100 measures. Together, present findings provide EEG evidence of lower task-based connectivity among first-episode SZ, reflecting disruptions of DMN functions that support cognitive processes. Attentional processes captured by N100 appear to be supported by different neural mechanisms.
PubMed: 38924105
DOI: 10.1111/psyp.14627 -
JAMA Psychiatry Jun 2024The emergence of psychotic symptoms in Alzheimer disease (AD) is associated with accelerated cognitive and functional decline that may be related to disease pathology.
IMPORTANCE
The emergence of psychotic symptoms in Alzheimer disease (AD) is associated with accelerated cognitive and functional decline that may be related to disease pathology.
OBJECTIVE
To investigate the longitudinal dynamics of plasma tau phosphorylated at threonine 181 (p-tau181) and neurofilament light chain protein (NfL) levels in association with the emergence of psychotic symptoms (delusions and hallucinations) in the context of AD.
DESIGN, SETTING, AND PARTICIPANTS
This cohort study used longitudinal data from the Alzheimer Disease Neuroimaging Initiative (ADNI). Baseline analyses compared patients with mild cognitive impairment (MCI) and AD (both with psychosis [AD+P] and without psychosis [AD-P]) and participants who were cognitively unimpaired (CU). For the longitudinal analysis, participants with MCI and AD were subdivided into patients with evidence of psychosis at baseline (AD+P baseline) and patients free of psychosis at baseline who showed incidence of psychosis over the course of the study (AD+P incident). Study data were analyzed between June and November 2023.
EXPOSURES
Plasma p-tau181 and NfL measures in individuals with MCI and AD, both with and without psychosis.
MAIN OUTCOMES AND MEASURES
Plasma p-tau181 and NfL quantifications up to 48 months and concurrent assessments of presence or absence of delusions and hallucinations via the Neuropsychiatric Inventory (NPI) questionnaire.
RESULTS
The cohort included 752 participants with AD (mean [SD] age, 74.2 [7.7] years; 434 male [57.7%]). A total of 424 CU participants had a mean (SD) age of 75.4 (6.6) years of whom 222 were female (52.4%). In the longitudinal analysis of p-tau181 trajectories of the AD+P group, the group of patients who showed incidence of psychosis over the course of follow-up (AD+P incident) demonstrated an associated increase in plasma p-tau181 levels compared with the group of patients who had psychosis at baseline (AD+P baseline) and showed an associated decrease in plasma p-tau181 levels (F4, 117 = 3.24; P = .01). The mean slope of p-tau181 change was significantly different in AD+P incident and AD+P baseline groups (F5,746 = 86.76, P < .0001) and when only individuals with amyloid-β positivity (Aβ+), which was determined using positron emission tomography, were compared (F5,455 = 84.60, P < .001). Patients who experienced psychosis at any time had increased levels of NfL relative to those who never experienced psychosis.
CONCLUSIONS AND RELEVANCE
Results of this cohort study suggest that the emergence of psychosis in AD was associated with elevations in plasma levels of p-tau181, highlighting the potential utility of plasma p-tau181 as a biomarker of neuropsychiatric illness in AD, which could have implications for predictive and treatment response strategies.
PubMed: 38922609
DOI: 10.1001/jamapsychiatry.2024.1389 -
Schizophrenia Research Jun 2024The role of basic neurocognitive function in delusions is unclear despite the association to difficulties in reasoning and decision-making. We investigated 812...
The role of basic neurocognitive function in delusions is unclear despite the association to difficulties in reasoning and decision-making. We investigated 812 individuals with schizophrenia spectrum disorders (SSD) using a broad neuropsychological test battery encompassing motor and mental processing speed, working memory, learning and memory, and executive function. Premorbid and current intellectual function was assessed with NART and WASI. Delusion level and other clinical symptoms were measured with the PANSS and GAF. Hierarchical and k-means cluster analysis using standardized scores showed the presence of two separate clusters where the group with the higher delusion level (n = 291) was characterized by more severe neurocognitive deficits (>1.5 standard deviations below the healthy control mean), higher PANSS scores, lower GAF scores, and lower intelligence levels compared to the cluster with mild impairments (n = 521). We conclude that a higher delusion level is related to neurocognitive deficits across domains. Further, the validity of the two separate clusters was indicated by significant differences in clinical symptoms, everyday function, and intellectual ability. Compared to those with mild delusion levels, SSD patients with higher delusion levels seem particularly disadvantaged, with co-occurring general symptoms and lower daily function, underscoring the need for clinical and psychosocial support programs. A limitation of this study is the cross sectional design. Longitudinal studies are needed to determine the causal relationship between delusions and neurocognitive function.
PubMed: 38917554
DOI: 10.1016/j.schres.2024.06.028 -
Nordic Journal of Psychiatry Jun 2024The Positive and Negative Syndrome Scale (PANSS) is one of the most commonly used assessment tools for measuring psychotic symptoms. The Psychotic Symptom Rating Scales...
Measuring the concurrent validity of the norwegian versions of the psychotic symptom rating scales (PSYRATS) and the positive scale from the positive and negative syndrome scale (PANSS).
PURPOSE
The Positive and Negative Syndrome Scale (PANSS) is one of the most commonly used assessment tools for measuring psychotic symptoms. The Psychotic Symptom Rating Scales (PSYRATS) is another instrument created specifically to assess delusions and auditory hallucinations. However, research on the concurrent validity of PSYRATS with PANSS is limited. There are also inconsistent findings regarding the association between the PSYRATS scales and the PANSS positive scale. The present study aims to add to the understanding of the concurrent validity of these measures, while also incorporating a broader measure of psychiatric symptoms (the symptom scale from the Global Assessment of Functioning Scale - split version, GAF-S).
MATERIALS AND METHODS
Spearman's Rank Order Correlations (rho) were calculated for scores from the PANSS positive scale, PSYRATS and GAF-S in a sample of 148 participants with psychotic disorders at three time points.
RESULTS
The findings indicate concurrent validity between PSYRATS and PANSS, while the PSYRATS scales were not consistently correlated with GAF-S.
CONCLUSIONS
PSYRATS may be a valid assessment tool for evaluating psychotic symptoms. The utility of PSYRATS in research and clinical practice should be investigated further.
PubMed: 38905132
DOI: 10.1080/08039488.2024.2367638 -
Journal of Huntington's Disease Jun 2024Huntington's disease (HD) is an autosomal dominant disorder that affects the basal ganglia, caused by CAG repeats in the huntingtin gene. Delusional infestation (DI)...
Huntington's disease (HD) is an autosomal dominant disorder that affects the basal ganglia, caused by CAG repeats in the huntingtin gene. Delusional infestation (DI) is a rare psychotic manifestation of the disease. This report presents two cases of HD patients with DI, both middle-aged females. The first patient achieved remission of DI with olanzapine, later cross-tapered to risperidone, but had spontaneous relapses. The second experienced gradual resolution of DI with risperidone in the setting of iron repletion and amantadine discontinuation, although her other psychotic symptoms remained. These cases shed light on an uncommon condition and may help guide understanding of the most effective treatment for it.
PubMed: 38905053
DOI: 10.3233/JHD-240013 -
Cureus May 2024The abuse of inhalants like nitrous oxide (NO), readily available worldwide, has remained a prominent public health problem during the last few decades. Literature...
The abuse of inhalants like nitrous oxide (NO), readily available worldwide, has remained a prominent public health problem during the last few decades. Literature reveals increased use during the previous pandemic, particularly regarding recreational use. There is limited evidence-based data available to relate the abuse of NO with psychosis. Therefore, this case report of a 22-year-old adult with no previous psychiatry history, reportedly abusing 75-100 canisters of NO per day during the last pandemic COVID-19 lockdown, highlights the relationship between (NO) abuse and the symptoms evolved including delusions, auditory hallucinations, and disorganized cognition. All the laboratory findings and results from imaging modalities were inconsistent for any organic cause of the symptoms. The case then underwent treatment with antipsychotic medications and a multidisciplinary model, which improved the symptoms gradually. The case, in particular, discusses NO abuse, which is widespread in European Union countries, including the UK and the Republic of Ireland, and its chronic use puts one at a higher risk of developing psychosis, personality changes, affective lability, anxiety, depression, cognitive impairment, and myeloneuropathy. The sale of NO for its psychoactive properties is prohibited in many countries, including the Republic of Ireland, as per legislation. However, NO is not a controlled drug, meaning it is not a crime to possess NO. This case report manifests the psychopathy caused by abuse of NO, which would further attract specialists in the field to conduct epidemiological studies for prevention at the primary level.
PubMed: 38903353
DOI: 10.7759/cureus.60634