La schizotypie est un trait de personnalité caractérisé par un niveau subclinique de symptômes de la schizophrénie, avec des caractéristiques dites positives (croyances et perceptions inhabituelles) ou négatives (retrait et anxiété sociale). Cette thèse a pour but de mieux comprendre comment la schizotypie s'articule avec d'autres dimensions psychopathologiques.Dans une première partie nous avons étudié les liens entre schizotypie et traits autistiques dans 2 populations d'étudiants scientifiques au moyen d'analyses par classification. Une première analyse sur la base des traits schizotypiques et autistiques a identifié 4 groupes avec des profils distincts, dont un cluster à haut niveau de traits. Cette combinaison de traits est associée à des signes de dégradation psychopathologique (symptômes anxieux et dépressifs, attachement insécurisé) et à de moindres performances académiques. Une deuxième étude propose une typologie des étudiants en fonction des traits schizotypique, autistique et cyclothymique. Cette typologie fait apparaître un cluster à hauts traits, avec un niveau élevé de symptômes de dépression et d'idéation suicidaire et de moindres résultats universitaires. Ces 2 études suggèrent donc que la combinaison de traits schizotypes et autistiques a une influence négative sur la réussite dans le domaine scientifique, en lien avec une comorbidité dépressive.La deuxième partie établit une typologie du jeune adulte afin de réexaminer le concept de "schizotypie saine", défini comme trait de schizotypie positive sans autre dimensions de la schizotypie. Nos résultats confirment que la shizotypie positive est associée à des bénéfices (e.g., qualité perçue des relations interpersonnelles) mais aussi à des traits de troubles de la personnalité et à des symptômes psychopathologiques, ce qui interpelle le concept de schizotypie saine. Dans une dernière étude nous avons identifié des biais illustrant l’impression que la schizotypie positive est plus saine qu’en réalité. / Schizotypy is a personality trait characterized by subclinical levels of schizophrenia symptoms, including positive (odd beliefs and unusual perceptions) or negative (withdrawal and social anxiety) features. This thesis aimed at a better understanding of how schizotypy articulates with other psychopathological dimensions.As a first part, we studied the links between schizotypy and autistic traits in 2 samples of scientific college students, using a cluster analysis. A first analysis based on schizotypal and autistic dimensions identified 4 groups with distinct profiles, including a cluster with high levels of traits. This combination of traits was associated with significant psychopathological degradation (anxiety and depressive symptoms, insecure attachment) and with lesser academic performances. A second study identified a typology of students based on schizotypal, autistic and cyclothymic traits. This typology showed a high traits cluster with elevated levels of depressive symptoms and suicidal ideations, and lesser academic results. These 2 studies thus suggest that association of schizotypal and autistic traits could impair success in scientific background, in relationship with a depressive comorbidity.The second part identified a typology of young adults aiming at reassessing the concept of "healthy schizotypy", defined as a trait of positive schizotypy without other schizotypal dimensions. Our results confirm that positive schizotypy is associated with benefits (e.g., perceived quality of interpersonal relations) but also with traits of personality disorders and psychopathological symptoms, which questions the concept of healthy schizotypy. In a last study we identified biases illustrating the impression that positive schizotypy may seem healthier than in reality.

Le trouble de la théorie de l’esprit (ToM) observé dans la schizophrénie et la schizotypie pourrait résulter d’anomalies élémentaires de traitement du contexte. La compréhension de l’ironie, en tant qu’exercice de ToM contexte-dépendant, constitue un moyen privilégié de tester cette hypothèse. À l’aide de mesures comportementales et électrophysiologiques, l’objectif principal de ce travail était de préciser la place des anomalies des processus de contextualisation dans le trouble de la ToM dans la schizotypie-schizophrénie en utilisant le paradigme de l’ironie. Le second objectif était d’identifier les conditions dans lesquelles ces anomalies de la ToM se manifestent et celles dans lesquelles elles peuvent être compensées. Nos résultats suggèrent (i) que les difficultés de ToM dans la schizotypie-schizophrénie résultent d’anomalies de traitement du contexte, (ii) que ces difficultés concernent spécifiquement la mise à jour de la représentation des états mentaux en fonction du contexte, soit un processus sous-tendu par des stratégies contextuelles rétroactives connues pour être altérées dans la schizotypie-schizophrénie et (iii) que la structuration du contexte sémantique permet d’améliorer les capacités de ToM dans le spectre de la schizophrénie, tandis que la présence d’un co-acteur inconnu semble inhiber ces capacités. Nos résultats soulignent par ailleurs un lien entre l’altération de la ToM et les difficultés sociales des participants. En conclusion, ce travail désigne les processus de contextualisation comme une cible cruciale des programmes de remédiation de la cognition sociale dans les troubles du spectre de la schizophrénie. / Theory of mind disturbances are a core manifestation of schizophrenia spectrum disorders. They contribute to the social handicap associated with the pathology, leading to disruption in autonomy, professional achievement, and interpersonal relationships. According to several authors, these disturbances may be due to a contextual impairment. Irony comprehension as a context-dependent ToM exercise is an ideal way to test this hypothesis. The first aim of this work was to clarify the contextual impairment’s role in ToM disturbances in schizotypy-schizophrenia using the paradigm of irony through behavioral and electrophysiological measures. The second aim was to identify the conditions in which these ToM disturbances occur and the conditions in which they can be compensated. Our results suggest that (i) ToM difficulties in schizotypy-schizophrenia result from abnormalities in context processing, (ii) these difficulties relate specifically to the updating of the mental states’ representation according to the context, e.g. a mentalizing process underlayed by retroactive contextual strategies known to be altered in schizotypy-schizophrenia, and (iii) structuring the semantic context can improve ToM's abilities in the schizophrenia’s spectrum, while the presence of an unknown co-actor seems to inhibit these abilities. Our results also highlight a link between the participant’s ToM disturbances and their social difficulties. In conclusion, this work indicates the relevance of cognitive remediation programs that target contextual processing in schizophrenia spectrum disorders.

Schizophrenia is associated with deficits in social cognition and emotion processing, but it is not known how these deficits relate to other domains of neurocognition and whether they might contribute to psychosis development. The current dissertation approaches this question by looking at the relationship between psychosis proneness and face emotion recognition ability, a core domain of social-emotional processing. Psychosis proneness was inferred by the presence of psychosis-like characteristics in otherwise healthy individuals, using self-report measures. Face emotion recognition ability was found to be associated with psychosis-proneness across four large web-based samples and one lab sample. These associations were relatively specific, and could not be explained by differences in face processing or IQ. Using functional magnetic resonance imaging (fMRI), psychosis-proneness was linked with reduced neural activity in brain regions that underlie normal face emotion recognition, including regions that are implicated in self-representation. Additional experiments were conducted to explore psychosis-proneness related differences in self-representation, and a relationship was revealed between cognitive-perceptual (positive) dimensions of psychosis-proneness and (1) flexibility in the body representation (as measured by the rubber hand illusion), and (2) self-referential source memory (but not self-referential recognition memory). Neither of these relationships, however, explained the association between psychosis-proneness and face emotion recognition ability. These findings indicate that psychosis vulnerability is related to neural and behavioral differences in face emotion processing, and that these differences are not a secondary characteristic of psychotic illness. Moreover, poorer emotion recognition ability in psychosisprone individuals is not explained by generalized performance, IQ, or face processing deficits. Although some dimensions of psychosis-proneness were related to differences in measures of self-representation, no evidence was found that these abnormalities contribute to psychosisproneness related differences in emotion recognition ability. / Psychology

The present study aimed to investigate the influences of socio-cultural context on content of delusions within schizophrenic patients among three different geographical areas in Saudi Arabia and to estimate the prevalence of schizotypal personality within the non-clinical Saudi population. Methods: 148 patients meeting DSM-IV criteria of schizophrenia were drawn from in-patient sections of mental health hospitals in three areas of study (Riyadh, Jeddah, and the Eastern Province), and 364 participants were recruited for comparison groups from Saudi universities and general medical practices in the same areas. The study utilized the following instruments: Scale for the Assessment of Positive Symptoms (SAPS), Scale for the Assessment of Negative Symptoms (SANS), the MacArthur-Maudsley Delusions Assessment Schedule (MMDAS), the World Health Organization (WHO) Life Events Schedule, the Aetiological Beliefs Questionnaire (ABQ), and the Schizotypal-Personality Questionnaire (SPQ). Results: Firstly: there were significant main effects of residence and sex on the three dependent SPQ scales, and females and Riyadh area residents scored higher on all dependent SPQ scales especially on the cognitive scale. Secondly: persecutory delusions were the most common delusions among schizophrenic patients followed by delusions of being controlled, and the frequency of persecutory delusions was significantly higher in females and in the Riyadh area. Thirdly: only delusions of jealousy were specifically associated with violent behaviours among schizophrenic patients. Finally: ABQ showed that both supernatural and psychological explanations of illness were common among both control and clinical groups. Qualitative analysis of the content of delusions revealed socio-cultural and gender-related issues that were strongly reflected in the themes and content of delusions. Conclusion: Content analysis of delusions in a Saudi schizophrenic sample showed strong effects of the socio-cultural context and stress points such as racism and gender inequality, and gender and regional culture affected both the frequency with which persecutory delusions were observed, and the mean scores of schizotypal personality in a non-clinical sample.

[Truncated abstract] Atypical handedness is found to be more prevalent in schizophrenia patients than in psychiatric and normal controls, suggesting atypical brain lateralisation, particularly of regions associated with language. This ‘behavioural aberration’ is commonly considered as a marker of disturbed neurodevelopment, which is usually indexed by minor physical abnormalities. A prevailing view in the literature is that the atypical lateralisation of hand preference provides an additional index for the neurodevelopmental hypothesis of schizophrenia. Consistent with this hypothesis, an atypical lateralisation of hand preferences can also be considered as a consequence of environmental agents that might have interfered with early embryonic development. Notwithstanding the above, an atypical lateralisation of hand preferences can occur as a result of genetic factors as well as an interaction between genetic and environmental factors. The overall objective of this thesis was to advance existing knowledge on atypical laterality in schizophrenia by addressing its various (though related) aspects, including measurement, classification and conceptualisation. Atypical lateralisation of hand preferences in schizophrenia patients was approached by five separate studies. ... Overall, this thesis argues that the causes of atypical lateralisation of hand preferences are due to combined genetic and environmental factors and that its use as a marker of vulnerability to schizophrenia is limited. A cautious interpretation of various associations between the laterality and other measures, particularly cognitive measures, is advised until a broad agreement on the true nature of handedness is reached.

Schizophrenia is a neuropsychiatric disorder lying at the extreme of a spectrum of disorders that possibly share a common abnormality in neural connectivity. Efforts to reverse the core cognitive manifestations of schizophrenia using drug treatments have so far been unsuccessful. This thesis investigates the cognitive abnormalities and their electrophysiological correlates across the schizophrenia spectrum in order to identify and validate biomarkers for proof of concept studies of cognitive enhancers. Such studies in milder disorders of the schizophrenia spectrum such as schizotypal personality trait may be a crucial method in identifying new effective compounds, as reviewed in Chapter 3, and tested in Chapter 4. The latter features the results of a large three-centre study which probed the sensitivity of several neuropsychological measures to the schizotypy phenotype, as well as to the effects of amisulpride, risperidone and nicotine. Schizotypal volunteers showed impaired performance only on the more difficult tasks. The most consistent pharmacological finding was that amisulpride tended to improve performance in the high schizotypy group but to impair it in the average schizotypy controls. One interpretation is that the ability of low dose amisulpride to enhance dopamine function in frontal cortex reversed an impairment of dopamine function present in the high schizotypes which is thought to occur in schizophrenia. Chapter 5 explored the methodological question of whether low or average schizotypy individuals should be used as controls in cognitive comparisons versus high schizotypy. The results suggest that low schizotypes have the most intact cognitive performance and are therefore the control group of choice. Chapters 6, 7 and 8 tested the hypothesis that cognitive deficits are part of a larger information processing abnormality in the schizophrenia spectrum. In accordance, both high schizotypy and schizophrenia patients exhibited reduced amplitude of an early visual evoked potential P1 (Chapters 6 and 8, respectively) and disruptions of the underlying evoked neural oscillations (Chapters 7 and 8). The pattern of abnormalities suggested an inefficient top-down modulation of perception in the schizophrenia spectrum. These data argue that cognitive abnormalities and their electrophysiological correlate may be sensitive biomarkers of the core dysconnectivity deficit in schizophrenia. This thesis supports their use in proof of concept studies to foster the development of cognitive enhancers.

Abstract Schizophrenia is a complex mental health disorder and its etiology can be investigated based on different theoretical prerequisites. The present thesis examines schizophrenia from the neurodevelopmental and psychosis continuum perspectives. Neurodevelopmental theories of schizophrenia see abnormalities in the developing nervous system as early predictors of vulnerability to the disease. Schizophrenia can be seen also as a progressive disorder and a continuum of symptomatology from personality traits (schizotypy) to full-blown schizophrenia. The aim of the present thesis is to study incidence of schizophrenia; prevalence of schizotypy; and associations between schizophrenia and schizotypy with early motor developmental milestones. The research design includes prospective cohort studies and systematic review, and meta-analysis. In two successive Northern Finland Birth Cohorts (NFBC) studies, 20 years apart (1966 and 1986), the incidence of schizophrenia remained the same, but the incidence of other psychoses and therefore all psychoses was higher in NFBC 1986. In NFBC 1966, mean schizotypy scores were among the lowest and the highest scores among 24 general population studies. When early motor developmental milestones were investigated in the meta-analyses (3 to 5 studies), a significant small effect size for walking, sitting, and standing unsupported was found with respect to adult schizophrenia. When schizotypy outcome was studied in the NFBC 1966, later achievement of turning from back to tummy, touching thumb with index finger, standing up, sitting unsupported, and walking with support were found to be associated with an increase in schizotypy scales and varied somewhat by gender. To conclude, there have been changes in the incidence of all psychoses but not in schizophrenia between the two NFBCs. This is in line with other studies on the trends of incidence of psychoses, which highlights the role of changes in diagnostic systems and practices that can influence rates. In this project, mean schizotypy scores were both among the highest and the lowest estimates in the studies on schizotypy in the general population. Early motor developmental milestones were both predictors of schizophrenia and schizotypy, and thus this finding supports both the neurodevelopmental and psychosis continuum approaches to the aetiology of schizophrenia. / Tiivistelmä Skitsofrenia on monimuotoinen mielenterveyden häiriö, jonka etiologiaa voidaan tutkia erilaisissa teoreettisissa viitekehyksissä. Tämä väitöskirja tutkii skitsofreniaa neurologisen kehityksen ja psykoosin jatkumon näkökulmista. Skitsofrenian neurokehitykselliset teoriat pitävät kehittyvän keskushermoston poikkeavuuksia varhaisina skitsofrenian alttiuden ennustajina. Skitsofreniaa voidaan pitää myös progressiivisena sairautena ja oireiden jatkumona persoonallisuuden piirteistä (skitsotypaalisuudesta) täysimittaiseen skitsofreniaan. Tämän väitöskirjatutkimuksen tavoitteena on tutkia skitsofrenian ilmaantuvuutta, skitsotypaalisten piirteiden yleisyyttä ja skitsofrenian ja skitsotypaalisten piirteiden yhteyttä varhaiseen motoriseen kehitykseen. Tutkimusasetelmina ovat prospektiiviset syntymäkohortit, systemaattinen katsaus ja meta-analyysi. Kahdessa peräkkäisessä 20 vuoden välein kerätyssä Pohjois-Suomen syntymäkohortissa (1966 ja 1986) skitsofrenian ilmaantuvuus pysyi samana, mutta muiden psykoosien ja siten kaikkien psykoosien ilmaantuvuudet olivat korkeampia vuoden 1986 syntymäkohortissa. Vuoden 1966 syntymäkohortissa negatiivisen skitsotypaalisuuden piirteet olivat korkeita ja positiivisen skitsotypaalisuuden piirteet alhaisia verrattuna 24 muuhun väestöaineistoon. Varhaisen motorisen kehityksen ja aikuisiän skitsofrenian välistä yhteyttä tutkittiin meta-analyysin (3–5 tutkimusta) avulla. Tilastollisesti merkitsevä pieni negatiivinen yhteys löytyi aikuisiän skitsofrenian ja kävelemään, istumaan ja seisomaan oppimisen välillä. Pohjois-Suomen vuoden 1966 syntymäkohortissa skitsotypaaliset piirteet liittyivät hitaampaan vatsalleen kääntymisen, peukalo-etusormi otteen, seisomisen, tuetta istumisen ja tuen kanssa kävelemisen oppimiseen. Näissä yhteyksissä oli vaihtelua tutkittavan sukupuolen mukaan. Yhteenvetona voidaan todeta, että psykoosien ilmaantuvuus on kasvanut Pohjois-Suomen syntymäkohorteissa, mutta skitsofrenian ei. Tämä on linjassa aikaisempien tutkimusten kanssa. On kuitenkin huomioitava myös diagnostisten järjestelmien ja käytäntöjen merkitys näiden muutosten arvioimisessa. Varhainen motorinen kehitys ennusti sekä skitsofreniaa että skitsotypaalisia piirteitä. Havainto tukee sekä neurokehityksellistä että psykoosin jatkumoon liittyvää lähestymistapaa skitsofrenian etiologiassa.

The phenomenon of somatosensory attenuation describes the perception that self-generated touch feels weaker than externally generated touch of identical intensity. Previous studies have shown that besides intensity, self-generated touches feel less pleasant and less ticklish than identical externally generated touches. However, previous studies did not systematically assess attenuation across a range of stimuli that can elicit intensity, pleasantness, and ticklishness more efficiently. This thesis aims to replicate these previous observations across a range of tactile stimuli of different intensities and velocities and investigate whether people who attenuate their self-generated touches to a greater extent do so for all aforementioned qualities. Previous studies have shown that participants with lower levels of somatosensory attenuation have more schizotypal personality traits. Twelve volunteers participated in three perceptual tasks where they received touches on their sole generated either by a robot(External) or the participants(Self). Following the strokes, participants had to rate the sensation from 0(not at all) to 100(extremely). For the intensity task, we manipulated the intensity of the applied forces (1,2,3,4N). For the pleasantness and ticklishness tasks, we manipulated the velocity of the applied strokes (0.3,1,10,30cm/s). After the tasks, participants completed a Schizotypal Personality Questionnaire (SPQ). Significant somatosensory attenuation was observed in all tasks, but for specific, not all, stimuli: forces of 4N in terms of intensity, strokes of 1cm/s in terms of pleasantness, and strokes of 10cm/s and 30cm/s in terms of ticklishness. These results suggest that the ability to suppress the tactile consequences of self-generated touch occurs in all three tactile qualities.

No description available.

Schizotypy, a complex construct linked to schizophrenia-related traits, encompasses positive, negative, and disorganized symptoms. This study offers a review of the concept of schizotypy, including its historical evolution, tracing it from Bleuler's early mention in 1911 to Meehl's continuum model. Embracing a dimensional perspective, this research underscores the interplay of biological, psychological, and social factors in understanding schizotypy. Deficits in sustained attention and working memory within schizotypy remain underexplored, with prior studies yielding inconsistent results. Adaptive functioning deficits in individuals with schizotypy are also inadequately understood. Examining a college student population, this investigation utilized scores on the Schizotypal Personality Questionnaire – Brief Revised (SPQ-BR) to psychometrically define schizotypy, and it used the Community Assessment of Psychic Experiences (CAPE-42), World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0), Continuous Performance Task (CPT-IP) and Visuospatial n-Back Task to assess the hypotheses. This was accomplished by comparing 60 individuals in the schizotypy group with 60 carefully matched controls. Contrary to expectations, those with schizotypy exhibited superior performance on sustained attention and visuospatial working memory tasks compared to controls, challenging the established literature, and warranting replication. The study addresses methodological gaps by using carefully matched control groups and employing innovative online cognitive tests. Despite observed cognitive strengths in performance, a paradox emerged as schizotypal individuals self-reported lower cognitive functioning, suggesting the need to focus on metacognition in schizotypy in future studies. This study underscores the need for a comprehensive systematic assessment of emerging young adult populations to understand their current psychological functioning relative to other community samples. The association between schizotypy, positive psychotic-like experiences, and increased self-reported disability suggests a need for the development of preventive interventions. The Hierarchical Taxonomy of Psychopathology (HITOP) is suggested as a promising assessment system for schizophrenia spectrum disorders in college students.