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Canadian Journal of Physiology and... Jun 2021The hydrogen ion concentration ([H]) in intracellular cytoplasmic fluid (ICF) must be maintained in a narrow range in all species for normal protein functions. Thus,...
The hydrogen ion concentration ([H]) in intracellular cytoplasmic fluid (ICF) must be maintained in a narrow range in all species for normal protein functions. Thus, mechanisms regulating ICF are of fundamental biological importance. Studies on the regulation of ICF [H] have been hampered by use of pH notation, failure to consider the roles played by differences in the concentration of strong ions (strong ion difference, SID), the conservation of mass, the principle of electrical neutrality, and that [H] and bicarbonate ions [HCO] are dependent variables. This argument is based on the late Peter Stewart's physical-chemical analysis of [H] regulation reported in this journal nearly forty years ago (Stewart. 1983. Can. J. Physiol. Pharmacol. : 1444-1461. Doi:10.1139/y83-207). We start by outlining the principles of Stewart's analysis and then provide a general understanding of its significance for regulation of ICF [H]. The system may initially appear complex, but it becomes evident that changes in SID dominate regulation of [H]. The primary strong ions are Na, K, and Cl, and a few organic strong anions. The second independent variable, partial pressure of carbon dioxide (PCO), can easily be assessed. The third independent variable, the activity of intracellular weak acids ([A]), is much more complex but largely plays a modifying role. Attention to these principles will potentially provide new insights into ICF pH regulation.
Topics: Bicarbonates; Delusions; Hydrogen-Ion Concentration
PubMed: 33356898
DOI: 10.1139/cjpp-2020-0631 -
Psychopathology 2012Reduplicative paramnesia (RP) is a content-specific delusional misidentification syndrome (DMS) which has received little attention in the research literature relative... (Review)
Review
BACKGROUND
Reduplicative paramnesia (RP) is a content-specific delusional misidentification syndrome (DMS) which has received little attention in the research literature relative to other DMS. RP is thought to result from an organic rather than psychiatric cause distinguishing it from other DMS. Our systematic review examines the research literature investigating the prevalence, symptomatology and potential neurologic mechanisms underlying RP.
SAMPLING AND METHODS
MEDLINE, PsycINFO, and the Cochrane Library were searched (from 1966 to February 10, 2012) with the reference lists of relevant articles examined. Case reports, clinical studies and post-mortem studies focusing on, or referring to, RP were included.
RESULTS
There is a paucity of literature regarding the potential mechanisms underlying the psychological, cognitive and neurological aspects of RP. The available literature is limited by the lack of systematic clinical studies and in vivo investigations with current findings remaining only speculative. However, there does appear to be a consensus that RP may have a neurologic rather than psychiatric cause and that right and bifrontal lesions as well as the cognitive dissonance associated with memory, visuospatial and impaired conceptual integration are common factors in RP presentation.
CONCLUSIONS
This area requires further extensive systematic research with supplementary in vivo data. Current studies suggest that focal lesions within the frontal lobe may account for the onset of RP.
Topics: Cerebral Cortex; Delusions; Female; Humans; Male; Syndrome
PubMed: 22854269
DOI: 10.1159/000337748 -
Schizophrenia Bulletin Jul 2021
Topics: Adaptation, Psychological; Delusions; Humans; Male; Schizophrenia; Schizophrenic Psychology
PubMed: 33479761
DOI: 10.1093/schbul/sbaa189 -
Annals of Medicine Dec 1996The diagnosis of schizophrenia is made on the basis of a diverse set of characteristic signs and symptoms. These include disturbances in perception and inference,... (Review)
Review
The diagnosis of schizophrenia is made on the basis of a diverse set of characteristic signs and symptoms. These include disturbances in perception and inference, abnormalities in communication, behaviour and motor activity, and deficits in emotional expressivity, hedonic capacity and drive. No single symptom or set of symptoms is pathognomonic, and the question of which symptoms are indeed at the 'core' of schizophrenia has been an issue of much debate, opinion and study since the disorder was first described a century ago. In this review, the symptoms emphasized in current diagnostic criteria for schizophrenia are described and the relative importance of these symptoms in the evolution of the schizophrenia construct is discussed.
Topics: Delusions; Diagnosis, Differential; Guidelines as Topic; Hallucinations; Humans; Psychotic Disorders; Schizophrenia; Schizophrenia, Disorganized
PubMed: 9017111
DOI: 10.3109/07853899608999116 -
Perception 1994
Topics: Delusions; Humans; Illusions; Mental Recall; Philosophy; Psychophysics
PubMed: 7971104
DOI: 10.1068/p230249 -
Early Intervention in Psychiatry Dec 2022Thinking biases are posited to be involved in the genesis and maintenance of delusions. Persecutory delusions are one of the most commonly occurring delusional subtypes... (Review)
Review
AIM
Thinking biases are posited to be involved in the genesis and maintenance of delusions. Persecutory delusions are one of the most commonly occurring delusional subtypes and cause substantial distress and disability to the individuals experiencing them. Their clinical relevance confers a rationale for investigating them. Particularly, this review aims to elucidate which cognitive biases are involved in their development and persistence.
METHODS
MEDLINE, Embase, PsycINFO and Global Health were searched from the year 2000 to June 2020. A formal narrative synthesis was employed to report the findings and a quality assessment of included studies was conducted.
RESULTS
Twenty five studies were included. Overall, 18 thinking biases were identified. Hostility and trustworthiness judgement biases appeared to be specific to persecutory delusions while jumping to conclusions, self-serving attributional biases and belief inflexibility were proposed to be more closely related to other delusional subtypes. While the majority of the biases identified were suggested to be involved in delusion maintenance, hostility biases, need for closure and personalizing attributional biases were believed to also have aetiological influences.
CONCLUSIONS
These findings show that some cognitive biases are specific to paranoid psychosis and appear to be involved in the formation and/or persistence of persecutory delusions.
Topics: Humans; Delusions; Paranoid Disorders; Bias; Psychotic Disorders
PubMed: 35396904
DOI: 10.1111/eip.13292 -
BMJ Case Reports Apr 2021This is a case report of a middle-aged man with no psychiatric history who presented with severe anxiety and psychotic symptoms from COVID-19. Following his discharge...
This is a case report of a middle-aged man with no psychiatric history who presented with severe anxiety and psychotic symptoms from COVID-19. Following his discharge from intensive care unit, he was unable to sleep, was increasingly agitated and was observed hitting his head off the walls, causing haematomas. He remained highly anxious and developed paranoid delusions and auditory and tactile hallucinations, needing admission to a psychiatric ward. Treatment with antipsychotic medication gradually improved his symptoms in a few weeks. This case report highlights the new onset of psychosis due to COVID-19 infection. It demonstrates the importance of early identification and treatment of neuropsychiatric complications within an acute hospital setting. Furthermore, there is a need for research in this area to help in the prevention and treatment of such psychiatric complications due to COVID-19.
Topics: Antipsychotic Agents; COVID-19; Delusions; Humans; Male; Middle Aged; Psychotic Disorders; SARS-CoV-2; Treatment Outcome
PubMed: 33906867
DOI: 10.1136/bcr-2021-242538 -
CNS Neuroscience & Therapeutics Jul 2018Organic or secondary psychosis can be seen in diverse conditions such as toxic/metabolic disorders, neurodegenerative disease, and stroke. Poststroke psychosis is a rare... (Review)
Review
Organic or secondary psychosis can be seen in diverse conditions such as toxic/metabolic disorders, neurodegenerative disease, and stroke. Poststroke psychosis is a rare phenomenon, but its study has significantly contributed to the understanding of delusion formation. The evidence from case studies of patients with focal strokes shows that delusions develop following unilateral damage of the right hemisphere. The majority of patients with right hemisphere stroke do not develop delusions however, and advanced neuroimaging analysis has elucidated why this symptom develops in only a small proportion. Lesions of the right lateral prefrontal cortex or lesions with connectivity to this area correlate with delusional beliefs in this subgroup. Studies of patients with primary psychosis, for example schizophrenia, or under the influence of the psychotogenic drug ketamine, also show abnormal function of this area in relation to the severity of their abnormal beliefs. The conclusion of these studies is that the right lateral prefrontal cortex is 1 hub in a neural network which includes the basal ganglia and limbic system and receives inputs from midbrain dopamine neurones. In patients with schizophrenia, or at risk of psychosis, dopamine is dysregulated and evidence suggests that faulty dopamine signaling is the precursor of delusion formation. It is therefore likely that the mechanism of delusion formation is the same in both primary and secondary psychosis. This is consistent with the mainstay of treatment of both conditions being antipsychotic medication. However, antipsychotic medication in people with cerebrovascular disease should be avoided if at all possible. This is because epidemiological studies have found that antipsychotic use is associated with an increased risk of stroke and will thus compound the possibility of a further cerebrovascular accident.
Topics: Animals; Biology; Delusions; Humans; Pathology
PubMed: 29766653
DOI: 10.1111/cns.12973 -
Psychiatrike = Psychiatriki Dec 2023We read with interest the recent report on the definition, diagnosis, and clinical implications of religious delusions (RD).1 In our sample of 929 delusional...
We read with interest the recent report on the definition, diagnosis, and clinical implications of religious delusions (RD).1 In our sample of 929 delusional schizophrenia patients who had been admitted to two psychiatric hospitals in Germany between 2010 and 2014, 138 patients (15%) reported RD. In 569 cases, information on religious affiliation was available. Patients with religious affiliation did not differ from patients without religious affiliation in the frequency of RD [χ2(1,569)= 0.02, p= 0.885]. Furthermore, patients with RD did not differ from patients with other types of delusion (OD) in the duration of hospitalisation [t(924)= -0.39, p= 0.695], or the number of hospitalisations [t(927)= -0.92, p= 0.358]. Additionally, in 185 cases, information on Clinical Global Impressions (CGI) and Global Assessment of Functioning (GAF) was available at the beginning and end of the hospital stay. By CGI-scores, no difference was seen in morbidity of subjects with RD relative to subjects with OD on admission [t(183)= -0.78, p= 0.437] and discharge t(183)= -1.10, p= .273 . Likewise, GAF-scores on admission did not differ in these groups [t(183)= 1.50, p= 0.135]. However, a trend was noted for lower GAF-scores on discharge in subjects with RD [t(183)= 1.91, p= .057, d= 0.39, CI 95% (-0.12-0.78)]. While RD have often been associated with a poorer prognosis in schizophrenia,2,3 we argue that this need not apply to all domains. Mohr et al4 reported that patients with RD were less likely to maintain psychiatric treatment, but did not have a more severe clinical status than patients with OD. Iyassu et al5 found higher levels of positive, but also lower levels of negative symptoms in patients with RD compared to patients with OD. Groups did not differ in terms of length of illness or level of medication. Siddle et al6 reported higher symptom scores in patients with RD at their first presentation, but a similar response to treatment when compared to patients with OD after 4 weeks of treatment. Furthermore, Ellersgaard et al7 iindicated that first-episode psychosis patients with RD at baseline were more likely to be non-delusional at follow-ups conducted after years 1, 2 and 5 when compared to patients with OD at baseline. We conclude that RD may thus interfere with short-term clinical outcome. With regard to long-term effects more favourable observations exist8 and the interplay of psychotic delusions with non-psychotic beliefs still warrants further research.
Topics: Humans; Delusions; Psychotic Disorders; Schizophrenia; Hospitalization
PubMed: 37212804
DOI: 10.22365/jpsych.2023.012 -
Journal of Psychopharmacology (Oxford,... Nov 2016In 2007, we proposed an explanation of delusion formation as aberrant prediction error-driven associative learning. Further, we argued that the NMDA receptor antagonist... (Review)
Review
In 2007, we proposed an explanation of delusion formation as aberrant prediction error-driven associative learning. Further, we argued that the NMDA receptor antagonist ketamine provided a good model for this process. Subsequently, we validated the model in patients with psychosis, relating aberrant prediction error signals to delusion severity. During the ensuing period, we have developed these ideas, drawing on the simple principle that brains build a model of the world and refine it by minimising prediction errors, as well as using it to guide perceptual inferences. While previously we focused on the prediction error signal per se, an updated view takes into account its precision, as well as the precision of prior expectations. With this expanded perspective, we see several possible routes to psychotic symptoms - which may explain the heterogeneity of psychotic illness, as well as the fact that other drugs, with different pharmacological actions, can produce psychotomimetic effects. In this article, we review the basic principles of this model and highlight specific ways in which prediction errors can be perturbed, in particular considering the reliability and uncertainty of predictions. The expanded model explains hallucinations as perturbations of the uncertainty mediated balance between expectation and prediction error. Here, expectations dominate and create perceptions by suppressing or ignoring actual inputs. Negative symptoms may arise due to poor reliability of predictions in service of action. By mapping from biology to belief and perception, the account proffers new explanations of psychosis. However, challenges remain. We attempt to address some of these concerns and suggest future directions, incorporating other symptoms into the model, building towards better understanding of psychosis.
Topics: Animals; Association Learning; Brain; Delusions; Hallucinations; Humans; Ketamine; Psychoses, Substance-Induced; Receptors, N-Methyl-D-Aspartate; Reproducibility of Results
PubMed: 27226342
DOI: 10.1177/0269881116650087