Programme

Recently the European EU-GEI cohort study (Jongsma et al., 2018) reported up to 8-fold higher incidences of treated psychotic disorders between study sites (average of 21.4 patients per 100,000 inhabitants per year). This variation of prevalence is most certainly due to variations in genetic and environmental risk factors for schizophrenia. In this symposium we propose to review recent findings on the links between schizophrenia and respectively toxoplasma gondii infection, cannabis/tobaco use and childhood trauma (CT). Our findings from the FondaMental national multicentric FACE-SZ cohort suggest that Toxoplasma is almost 3 times more frequent in SZ population compared to general population in France (Fond et al., 2018). Significant odds ratios (ORs) with IgG antibodies were found in schizophrenia (OR 1.81, P < 0.00001). In the multivariate analyses, latent Toxoplasma infection has been significantly associated with higher PANSS negative and excitement subscores, with two specific symptoms (i.e., reference delusion and alogia) and with chronic low-grade peripheral inflammation (27.2% vs. 7.6%, OR = 3.8 [1.4-10.3], p = 0.004). Among late environmental factors, cannabis has been the focus of decades of research in schizophrenia. Very recently, the impact of tobacco consumption has also been debated. Individuals with schizophrenia consume almost twice as much as the general population and that they could represent a subgroup with specific socio-demographic and clinical characteristics. The self-medication hypothesis alone hardly accounts for the high prevalence of their smoking. We will focus on the links between cannabis/THC and tobacco/nicotine and schizophrenia, with an up-to-date review on current evidence (Mallet et al., 2017). In interaction with genetic and environmental factors, childhood trauma can impact psychopathology of schizophrenia and contribute to the emergence of psychosis via neurodevelopmental brain effects. We reviewed 15 studies exploring the associations between CT and brain abnormalities in schizophrenia (Cancel et al., 2019). Our findings suggest that CT could shape the psychopathology of schizophrenia through developmental effects on the brain, with predominant alterations in the prefrontal cortex, or in stress-related circuits affecting self-consciousness and social cognition. More specifically, the brain alterations observed in schizophrenia may be more a reflection of the consequences of CT than of the pathology itself.

Auteurs : A. Cancel (1), J. Mallet (2), G. Fond (3), F. Berna (4). - 1. Clinique Saint Clément, Saint-Clément de Rivière, France. 2. INSERM U1266, Institute of Psychiatry and Neurosciences of Paris (IPNP), France; Psychiatry Department, University Hospital Louis Mourier; Paris Diderot University, France. 3. Fondation FondaMental, Créteil, France; Aix-Marseille Univ, Faculté de Médecine - Secteur Timone, EA 3279: CEReSS -Centre d'Etude et de Recherche sur les Services de Santé et la Qualité de vie, 27 Boulevard Jean Moulin, 13005 Marseille, France. 4. Fondation FondaMental, Créteil, France; Hôpitaux Universitaires de Strasbourg, Université de Strasbourg, INSERM U1114, Fédération de Médecine Translationnelle de Strasbourg, Strasbourg, France.

Références : A. Cancel , S. Dallel , A. Zine , W. El-Hage , E. Fakra. Understanding the link between childhood trauma and schizophrenia: A systematic review of neuroimaging studies Neurosci Biobehav Rev. 2019;107:492-504. G. Fond, L Boyer , F. Schürhoff, et al. Latent toxoplasma infection in real-world schizophrenia: Results from the national FACE-SZ cohort. Schizophr Res. 2018;201:373-380. H.E. Jongsma , C. Gayer-Anderson , A. Lasalvia, et al.Treated Incidence of Psychotic Disorders in the Multinational EU-GEI Study. JAMA Psychiatry. 2018;75(1):36-46. J. Mallet , Y. Le Strat, F. Schürhoff, et al. Cigarette smoking and schizophrenia: a specific clinical and therapeutic profile? Results from the FACE-Schizophrenia cohort. Prog Neuropsychopharmacol Biol Psychiatry. 2017;79(Pt B):332-339.

Mots clés : schizophrenia, psychosis, cannabis, childhood trauma, toxoplasma, environment

Conflit d'intérêt : The authors declare no conflicts of interest in relation with their presented work.

Auteurs : -

Mental diseases represent a very heterogeneous categorical group, even within a given nosographic entity. Multifactorial approaches allow accounting for the clinical heterogeneity of mental disorders, the continuum between certain clinical dimensions, and even between the normal and the pathological. Among such dimensions, the psychotic phenotype constitutes an essential dimension of schizophrenic disorder. The dimensional approach allows for the search of psychotic experiences in most mental disorders as well as in the general population. Certain psychiatric disorders with psychotic symptoms could be the result of the interaction between early- and late- environmental factors and the neurodevelopment of the individual. Among late environmental factors, cannabis has been the focus of decades of research in schizophrenia. It is now recognized as an environmental risk factor, at least in vulnerable individuals. Very recently, the impact of tobacco consumption has also been debated. Individuals with schizophrenia consume almost twice as much as the general population and that they could represent a subgroup with specific socio-demographic and clinical characteristics. The self-medication hypothesis alone hardly account for the high prevalence of their smoking. We will focus on the links between cannabis/THC and tobacco/nicotine and schizophrenia, with an up-to-date review on current evidence. We need a better understanding of the impact of cannabis or tobacco on neurodevelopment, that can lead to a better etiopathogenic understanding, better prevention opportunities, and a personalized patient care.

Auteurs : Jasmina Mallet - Service de Psychiatrie et Addictologie du Pr Dubertret CHU Louis Mourier, APHP 178 rue des Renouillers 92700 COLOMBES

Références : Cigarette smoking and schizophrenia: a specific clinical and therapeutic profile? Results from the FACE-Schizophrenia cohort. Mallet J et al, Prog Neuropsychopharmacol Biol Psychiatry. 2017 Oct 3;79(Pt B):332-339. doi: 10.1016/j.pnpbp.2017.06.026. Heavy cannabis use prior psychosis in schizophrenia: clinical, cognitive and neurological evidences for a new endophenotype? Mallet J et al, Eur Arch Psychiatry Clin Neurosci. 2017 Oct;267(7):629-638. doi: 10.1007/s00406-017-0767-0. Tobacco Smoking and Psychotic-Like Experiences in a General Population Sample. Mallet et al, J Clin Psychiatry. 2018 Oct 2;79(6):17m11994. doi: 10.4088/JCP.17m11994. Smoking and schizophrenia in population cohorts of Swedish women and men: a prospective co-relative control study. Kendler et al, Am J Psychiatry. 2015 Nov 1;172(11):1092-100. doi: 10.1176/appi.ajp.2015.15010126. Smoking as a causal risk factor for schizophrenia. Gage et al, Lancet Psychiatry. 2015 Sep;2(9):778-9. doi: 10.1016/S2215-0366(15)00333-8.

Mots clés : schizophrenia ; tobacco ; cannabis ; environment ; neurodevelopment

Conflit d'intérêt : aucun

Recently the European EU-GEI cohort study (Jongsma et al., 2018) reported up to 8-fold higher incidences of treated psychotic disorders between study sites (average of 21.4 patients per 100,000 inhabitants per year). This variation of prevalence is most certainly due to variations in genetic and environmental risk factors for schizophrenia. Childhood trauma (CT) is a major vulnerability factor in schizophrenia. In interaction with genetic and environmental factors, they shape psychopathology of schizophrenia and contribute to the emergence of psychosis via neurodevelopmental brain effects. Such early stressors are associated with long-term changes in brain morphology, activity and connectivity in schizophrenia. Thus, researchers have hypothesized that, although a single diagnostic is used (schizophrenia), patients exposed to CT are clinically and neurobiologically distinct from unexposed patients. We reviewed 15 studies exploring the associations between CT and brain abnormalities in adult subjects with schizophrenia, schizoaffective disorder or first episode schizophrenia (Cancel et al., 2019). The most replicated result is the association in schizophrenia patients between CT and decreased total cerebral grey matter, particularly in the prefrontal cortex. In addition, studies suggest a different sensitivity to early stressors between schizophrenia subjects, their sibling and healthy unrelated subjects. In schizophrenia, CT is associated with alterations of white matter integrity in the inferior and superior longitudinal fasciculus, the inferior fronto-occipital fasciculus and the forceps major. Functional connectivity studies suggest an association between CT and a network including the amygdala, the anterior cingulate cortex, the precuneus/posterior cingulate cortex region and the temporo-parietal junction. Our findings suggest that CT could shape the psychopathology of schizophrenia through developmental effects on the brain, with predominant alterations in the prefrontal cortex, or in stress-related circuits affecting self-consciousness and social cognition. More specifically, the brain alterations observed in schizophrenia may be more a reflection of the consequences of CT than of the pathology itself.

Auteurs : A. Cancel - INSERM U1028 / CNRS UMR5292, PsyR2 Team, Lyon Neuroscience Research Center, Lyon, France ; Clinique Saint Clément, Groupe Clinipôle, Saint Clément de Rivière, France ; Clinique Rech, Ramsay Santé, Montpellier, France.

Références : A. Cancel , S. Dallel , A. Zine , W. El-Hage , E. Fakra. Understanding the link between childhood trauma and schizophrenia: A systematic review of neuroimaging studies Neurosci Biobehav Rev. 2019;107:492-504. H.E. Jongsma , C. Gayer-Anderson , A. Lasalvia, et al.Treated Incidence of Psychotic Disorders in the Multinational EU-GEI Study. JAMA Psychiatry. 2018;75(1):36-46.

Mots clés : schizophrenia, psychosis, childhood trauma, environment, MRI, DTI, VBM, fMRI, brain

Conflit d'intérêt : The authors declare no conflict of interest regarding the subjects of this communication.