scholarly journals From hallucinations to synaesthesia: a circular inference account of unimodal and multimodal erroneous percepts in clinical and drug-induced psychosis

2021 ◽  
Author(s):  
Pantelis Leptourgos ◽  
Vincent Bouttier ◽  
Sophie Deneve ◽  
Renaud Jardri
Keyword(s):  
Clinical Implications ◽  
Inhibitory Interneurons ◽  
Drug Induced ◽  
Sensory Inputs ◽  
High Prevalence ◽  
Sensory Modalities ◽  
Hierarchical Levels ◽  
Deep Layers ◽  
Drug Induced Psychosis ◽  
Levels Of Integration

Psychedelics are known to distort perception and induce visual and multimodal hallucinations as well as synaesthesia. This is in contradiction with the high prevalence of distressing voices in schizophrenia. Here we introduce a unifying account of unimodal and multimodal erroneous percepts based on circular inference. We show that amplification of top-down predictions (descending loops) leads to an excessive reliance on priors and aberrant levels of integration of the sensory representations, resulting in crossmodal percepts and stronger illusions. By contrast, amplification of bottom-up information (ascending loops) results in overinterpretation of unreliable sensory inputs and high levels of segregation between sensory modalities, bringing about unimodal hallucinations and reduced vulnerability to illusions. We delineate a canonical microcircuit in which layer-specific inhibition controls the propagation of information across hierarchical levels: inhibitory interneurons in the deep layers exert control over priors, removing descending loops. Conversely, inhibition in the supragranular layers counterbalances the effects of the ascending loops. Overall, we put forward a multiscale and transnosographic account of psychosis with important theoretical, conceptual and clinical implications.

scholarly journals Recognition and clinical implications of high prevalence of migraine in patients with Brugada syndrome and drug‐induced type 1 Brugada pattern

2020 ◽  
Vol 31 (12) ◽  
pp. 3311-3317
Author(s):  
Can Hasdemir ◽  
Figen Gokcay ◽  
Mehmet N. Orman ◽  
Umut Kocabas ◽  
Serdar Payzin ◽  
...  
Keyword(s):  
Brugada Syndrome ◽  
Clinical Implications ◽  
Drug Induced ◽  
High Prevalence ◽  
Brugada Pattern

scholarly journals Stability of the diagnosis of first-episode drug-induced psychosis

2011 ◽  
Vol 35 (6) ◽  
pp. 224-227 ◽  
Author(s):  
Aravind Komuravelli ◽  
Rob Poole ◽  
Robert Higgo
Keyword(s):  
Mental Health ◽  
First Episode ◽  
Clinical Implications ◽  
Psychiatric History ◽  
Schizophreniform Disorder ◽  
Drug Induced ◽  
Functional Psychosis ◽  
Drug Induced Psychosis ◽  
The Stability

Aims and methodTo assess the stability of the diagnosis of first-episode drug-induced psychosis over a follow-up period of at least 2 years. Patients with no psychiatric history who had been discharged from in-patient care between January 2002 and April 2006 with a firm diagnosis of drug-induced psychosis were identified. Follow-up information for at least the next 2 years or until discharge from mental health services was collected retrospectively from psychiatric records.ResultsNearly all of the patients who remained under psychiatric follow-up had a change in diagnosis, most commonly to a schizophreniform disorder. Those who were retained in follow-up had significantly longer index admissions than those discharged to primary care (P = 0.05).Clinical implicationsThis study suggests that many individuals diagnosed with drug-induced psychosis are further diagnosed as having a functional psychosis, usually schizophreniform in nature. This is compatible with the suggestion that individuals diagnosed with drug-induced psychosis are experiencing either the effects of drug intoxication or an ordinary functional psychosis complicated by incidental drug use.

Substance Misuse and Early Psychosis

2009 ◽  
Vol 17 (4) ◽  
pp. 291-294 ◽  
Author(s):  
Peter Tucker
Keyword(s):  
Substance Misuse ◽  
Current Knowledge ◽  
Early Psychosis ◽  
Intervention Programs ◽  
Drug Induced ◽  
High Prevalence ◽  
Specific Vulnerability ◽  
Drug Induced Psychosis ◽  
The Relationship ◽  
Review Current

Objective: This paper sought to review current knowledge about the relationship between substance misuse and early psychosis. Methods: A literature search was conducted using Medline and restricting the search to articles after 1996. Additional articles were sourced from reference lists of relevant articles. Results: There is a high prevalence of substance misuse among persons with early psychosis, with cannabis and alcohol featuring prominently. Substance misuse is associated with earlier onset and possibly more positive symptoms, although apparently not with greater cognitive impairment. Cannabis appears to confer an increased likelihood of developing schizophrenia in biologically vulnerable individuals. Amphetamines also cause psychosis which may become chronic, although specific vulnerability to this effect is less well established. Many cases of so-called ‘drug-induced psychosis’ become diagnosed as schizophrenia in later years. Specific intervention programs report positive outcomes with regard to substance misuse and the course of psychosis. Conclusions: Substance misuse should always be assessed in this patient group, bearing in mind the potential interactive causes of psychopathology. Intervention is of value in improving outcomes.

scholarly journals The Independent Evolution of Dorsal Pallia in Multiple Vertebrate Lineages

2021 ◽  
pp. 1-12
Author(s):  
Georg F. Striedter ◽  
R. Glenn Northcutt
Keyword(s):  
Olfactory Bulbs ◽  
Sensory Inputs ◽  
Independent Evolution ◽  
Sensory Modalities ◽  
Olfactory Input ◽  
Cartilaginous Fishes

Comparative neurobiologists have long wondered when and how the dorsal pallium (e.g., mammalian neocortex) evolved. For the last 50 years, the most widely accepted answer has been that this structure was already present in the earliest vertebrates and, therefore, homologous between the major vertebrate lineages. One challenge for this hypothesis is that the olfactory bulbs project throughout most of the pallium in the most basal vertebrate lineages (notably lampreys, hagfishes, and lungfishes) but do not project to the putative dorsal pallia in teleosts, cartilaginous fishes, and amniotes (i.e., reptiles, birds, and mammals). To make sense of these data, one may hypothesize that a dorsal pallium existed in the earliest vertebrates and received extensive olfactory input, which was subsequently lost in several lineages. However, the dorsal pallium is notoriously difficult to delineate in many vertebrates, and its homology between the various lineages is often based on little more than its topology. Therefore, we suspect that dorsal pallia evolved independently in teleosts, cartilaginous fishes, and amniotes. We further hypothesize that the emergence of these dorsal pallia was accompanied by the phylogenetic restriction of olfactory projections to the pallium and the expansion of inputs from other sensory modalities. We do not deny that the earliest vertebrates may have possessed nonolfactory sensory inputs to some parts of the pallium, but such projections alone do not define a dorsal pallium.

Lingual deficits in BDNF and NT3 mutant mice leading to gustatory and somatosensory disturbances, respectively

Development ◽  
1997 ◽  
Vol 124 (7) ◽  
pp. 1333-1342 ◽  
Author(s):  
C.A. Nosrat ◽  
J. Blomlof ◽  
W.M. ElShamy ◽  
P. Ernfors ◽  
L. Olson
Keyword(s):  
Taste Buds ◽  
Mutant Mice ◽  
Taste Bud ◽  
Physiological Data ◽  
Clinical Implications ◽  
Wild Type ◽  
Severe Reduction ◽  
Sensory Modalities ◽  
Per Se ◽  
Taste Discrimination

A combination of anatomical, histological and physiological data from wild-type and null-mutated mice have established crucial roles for BDNF and NT3 in gustatory and somatosensory innervation of the tongue, and indeed for proper development of the papillary surface of the tongue. BDNF is expressed in taste buds, NT3 in many surrounding epithelial structures. Absence of BDNF in mice leads to severely malformed taste bud-bearing papillae and severe reduction of taste buds, a loss of proper innervation of remaining taste buds and a loss of taste discrimination although not of the suckling reflex per se. In contrast, absence of NT3 leads to a massive loss of somatosensory innervation of lingual structures. These findings demonstrate distinct roles for BDNF and NT3 in the establishment of the complex innervation apparatus of the tongue with non-overlapping roles for the lingual gustatory and somatosensory systems. The distinction between different sensory modalities, being dependent on either BDNF or NT3 may also have clinical implications.

scholarly journals The "selfish brain" hypothesis for metabolic abnormalities in bipolar disorder and schizophrenia

2012 ◽  
Vol 34 (3) ◽  
pp. 121-128 ◽  
Author(s):  
Rodrigo Barbachan Mansur ◽  
Elisa Brietzke
Keyword(s):  
Bipolar Disorder ◽  
Energy Metabolism ◽  
Energy Supply ◽  
Clinical Implications ◽  
Metabolic Abnormalities ◽  
Compensatory Mechanisms ◽  
High Prevalence ◽  
Brain Theory ◽  
The Brain ◽  
Brain Energy

Metabolic abnormalities are frequent in patients with schizophrenia and bipolar disorder (BD), leading to a high prevalence of diabetes and metabolic syndrome in this population. Moreover, mortality rates among patients are higher than in the general population, especially due to cardiovascular diseases. Several neurobiological systems involved in energy metabolism have been shown to be altered in both illnesses; however, the cause of metabolic abnormalities and how they relate to schizophrenia and BD pathophysiology are still largely unknown. The "selfish brain" theory is a recent paradigm postulating that, in order to maintain its own energy supply stable, the brain modulates energy metabolism in the periphery by regulation of both allocation and intake of nutrients. We hypothesize that the metabolic alterations observed in these disorders are a result of an inefficient regulation of the brain energy supply and its compensatory mechanisms. The selfish brain theory can also expand our understanding of stress adaptation and neuroprogression in schizophrenia and BD, and, overall, can have important clinical implications for both illnesses.

scholarly journals Re: Drug-Induced Psychosis with Levetiracetam

2005 ◽  
Vol 50 (14) ◽  
pp. 948-948
Author(s):  
Marco Mula ◽  
Michael R Trimble
Keyword(s):  
Drug Induced ◽  
Drug Induced Psychosis

scholarly journals Kaleidoscope

2014 ◽  
Vol 205 (2) ◽  
pp. 166-167 ◽  
Author(s):  
Derek K. Tracy ◽  
Dan W. Joyce ◽  
Sukhwinder S. Shergill
Keyword(s):  
Violent Crime ◽  
Population Based ◽  
The Novel ◽  
Drug Induced ◽  
Persecutory Delusions ◽  
Appropriate Treatment ◽  
Cannabis Extract ◽  
Drug Induced Psychosis ◽  
The Uk

Drugs and violence are often observed as bedfellows; both have been associated with psychosis but the nature and timing of their relationships remains unclear. As part of the UK Prisoner Cohort Study, Keers et al prospectively followed up 967 prisoners convicted of sexual or violent offences (about a quarter of whom had a psychotic illness) in the community after release. Schizophrenia was associated with greater rates of violence, but the risk was mediated by untreated psychosis or when presenting with persecutory delusions – and no other definable psychopathology. Interestingly, drug-induced psychosis did not increase the risk of violence per se, once the substance misuse itself was accounted for. Does treatment have an impact on risk of violence in a population-based sample of patients with psychosis? Fazel et al demonstrated reductions in violent crime in patients during the time they were prescribed antipsychotics. Interestingly, the rates of violent crime were also reduced in patients with bipolar disorder who received mood stabilisers. Therefore, in addition to the effects of antipsychotics and mood stabilisers on relapse rates, their potential effects on violence and crime could be used to make decisions about management for these groups of patients. There is a clearer need for the appropriate treatment of prisoners with psychotic illnesses if their risk of violence is to be moderated. Cannabis is one of the most commonly used social drugs worldwide; it increases risk of psychosis, but there has been little to offer pharmacologically to those dependent upon this most prevalent illicit drug, and various trials of mood stabilisers, antidepressants and α2 adrenergic agonists have generally been disappointing. Allsop et al evaluated the novel cannabis extract nabiximols, containing cannabidiol – which has been shown to attenuate paranoia and euphoria – and tetrahydrocannabinol, delivered as a buccal spray. The active drug group showed statistically significant benefits in reduced withdrawal irritability, depression and cravings and remained longer in treatment. However, both placebo and drug groups showed reduced cannabis use at follow-up, with placebo being as effective as nabiximols in promoting longer-term cessation.

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