Role for positive schizotypy and hallucination proneness in semantic processing

Semantic processing underpins the organization of verbal information for both storage and retrieval. Deficits in semantic processing are associated with both the risk for and symptoms presented in schizophrenia. However, studies are mixed and could reflect the confounding effects of medication and symptom heterogeneity. Therefore, we considered whether two risk phenotypes, positive schizotypy and hallucinatory predisposition, present in the general population were associated with differential responding profiles for a semantic processing task. One hundred and eighty-three participants completed the Schizotypal Personality Questionnaire, Launay-Slade Hallucination Scale, National Adult Reading Test, a handedness measure, and a computerized semantic relatedness judgment task. Pairs of words were related through their dominant or subordinate meanings, or unrelated. Participants were divided into four groups using a mean split on cognitive-perceptual (positive) schizotypy and hallucination proneness. Significant differences between groups were found for reaction time on the semantic relatedness task, with the high cognitive-perceptual schizotypy groups responding significantly slower to all word pairs compared to their low scoring counterparts. There was some evidence that high hallucination proneness was associated with significantly faster reaction times which may reflect disinhibitive processes, however additional support is required. The results suggest that these two components of psychosis risk are associated with different patterns of responding to semantic processing. More diffuse activation of semantic information appeared to be associated with positive schizotypy, while those predisposed to hallucinations appeared to respond quicker. These results have significant implications in the re-conceptualization of hallucination proneness as distinct from positive schizotypy. Additional research is required to investigate the association between psychotic-like experiences separate from personality variables such as positive schizotypy and semantic processing

Schizotypy: Consideration of neurological soft signs, language and affective factors

Schizotypy is regarded as a trait vulnerability marker for psychosis. The study of this personality trait in otherwise healthy samples affords opportunities to research potential co-occurring risk factors for psychosis, without the confounds inherent to psychiatric diagnosis. The current thesis is focused on the expression of schizotypy alongside neurodevelopmental, language and affective risk factors for psychosis. The specific risk factors investigated were neurological soft signs (NSS), semantic processing, affective temperament, and psychological distress. Additionally, this thesis investigated whether propensity to hallucinate had an effect on these factors when combined with psychometric schizotypy. Language abnormalities have also been extensively researched in schizotypy and along the psychosis continuum. Given the overlap between the psychosis continuum and language abnormalities such as those seen in dyslexia, this thesis also sought to determine whether risk factors for psychosis are also present in a dyslexia sample. This thesis is made up of a combination of five studies, some of which are published and submitted manuscripts, with the remainder being manuscripts in preparation for publication. Study One investigated the relationship between schizotypy and distress. Affective temperament was found to mediate this relationship. Contrary to predictions hallucination predisposition was not found to exert significant effects on either the direct or indirect relationship between schizotypy and distress. Study Two explored whether NSS are expressed differently in those with high and low levels of schizotypy and additionally, whether hallucination predisposition interacts with this effect. Results indicated that those with high overall schizotypy express significantly more NSS, and that hallucination predisposition has additive effects on this association. Study Three looked at the expression of NSS in a dyslexia sample. It was found that individuals with dyslexia expressed a significantly greater amount of NSS compared to controls. Individuals with dyslexia also had significantly higher rates of schizotypy, which was found to contribute to the higher level of distress found in those with dyslexia compared to controls. Study Four investigated semantic processing capabilities of those with high and low positive schizotypy, as well as high and low hallucination predisposition. High levels of positive schizotypy resulted in slower reaction times compared to low positive schizotypy, whilst high hallucination predisposition resulted in faster reaction times compared to low hallucination predisposition. Study Five investigated semantic processing in a dyslexia sample. There was some evidence that the dyslexia group responded slower than controls. The dyslexia group also had difficulty discriminating degree of relatedness between semantic pairs, and schizotypy was found to contribute to this effect. This thesis concludes with a synthesis of the findings across the five studies. Theoretical and clinical implications are also considered, alongside limitations of the research and possible avenues for further enquiry. Overall, the results of this thesis indicate that individuals with high levels of schizotypy have associations with distress through affective temperament, as well as an increased expression of NSS, and abnormal semantic processing. Hallucination predisposition is not synonymous with schizotypy in its effects on these risk factors, suggesting schizotypy and propensity to hallucinate may have different mechanisms of effect. Dyslexia was associated with an increased expression of NSS, as well as semantic processing abnormalities that were contributed to by schizotypy. These findings are indicative of schizotypy and dyslexia having overlapping features, which may be suggestive of possible shared aetiologies

A comprehensive review of auditory verbal hallucinations: Lifetime prevalence, correlates and mechanisms in healthy and clinical individuals

Over the years, the prevalence of auditory verbal hallucinations (AVHs) have been documented across the lifespan in varied contexts, and with a range of potential long-term outcomes. Initially the emphasis focused on whether AVHs conferred risk for psychosis. However, recent research has identified significant differences in the presentation and outcomes of AVH in patients compared to those in non-clinical populations. For this reason, it has been suggested that auditory hallucinations are an entity by themselves and not necessarily indicative of transition along the psychosis continuum. This review will examine the presentation of auditory hallucinations across the life span, as well as in various clinical groups. The stages described include childhood, adolescence, adult non-clinical populations, hypnagogic/hypnopompic experiences, high schizotypal traits, schizophrenia, substance induced AVH, AVH in epilepsy, and AVH in the elderly. In children, need for care depends upon whether the child associates the voice with negative beliefs, appraisals and other symptoms of psychosis. This theme appears to carry right through to healthy voice hearers in adulthood, in which a negative impact of the voice usually only exists if the individual has negative experiences as a result of their voice(s). This includes features of the voices such as the negative content, frequency, and emotional valence as well as anxiety and depression, independently or caused by voices presence. It seems possible that the mechanisms which maintain AVH in non-clinical populations are different from those which are behind AVH presentations in psychotic illness. For example, the existence of maladaptive coping strategies in patient populations is one significant difference between clinical and non-clinical groups which is associated with a need for care. Whether or not these mechanisms start out the same and have differential trajectories is not yet evidenced. Future research needs to focus on the comparison of underlying factors and mechanisms that lead to the onset of AVH in both patient and non-clinical populations

Role for Positive Schizotypy and Hallucination Proneness in Semantic Processing

© Copyright © 2020 de Leede-Smith, Roodenrys, Horsley, Matrini, Mison and Barkus. Semantic processing underpins the organization of verbal information for both storage and retrieval. Deficits in semantic processing are associated with both the risk for and symptoms presented in schizophrenia. However, studies are mixed and could reflect the confounding effects of medication and symptom heterogeneity. Therefore, we considered whether two risk phenotypes, positive schizotypy and hallucinatory predisposition, present in the general population were associated with differential responding profiles for a semantic processing task. One hundred and eighty-three participants completed the Schizotypal Personality Questionnaire, Launay-Slade Hallucination Scale, National Adult Reading Test, a handedness measure, and a computerized semantic relatedness judgment task. Pairs of words were related through their dominant or subordinate meanings, or unrelated. Participants were divided into four groups using a mean split on cognitive-perceptual (positive) schizotypy and hallucination proneness. Significant differences between groups were found for reaction time on the semantic relatedness task, with the high cognitive-perceptual schizotypy groups responding significantly slower to all word pairs compared to their low scoring counterparts. There was some evidence that high hallucination proneness was associated with significantly faster reaction times which may reflect disinhibitive processes, however additional support is required. The results suggest that these two components of psychosis risk are associated with different patterns of responding to semantic processing. More diffuse activation of semantic information appeared to be associated with positive schizotypy, while those predisposed to hallucinations appeared to respond quicker. These results have significant implications in the re-conceptualization of hallucination proneness as distinct from positive schizotypy. Additional research is required to investigate the association between psychotic-like experiences separate from personality variables such as positive schizotypy and semantic processing

Neurological soft signs: Effects of trait schizotypy, psychological distress and auditory hallucination predisposition

Schizotypy is regarded as a trait vulnerability for psychotic disorders, yet alone is insufficient for development of a diagnosable disorder. Additional symptoms and psychological distress are necessary for help seeking and transition from an at risk mental state to a clinical diagnosis. The present study investigated the interaction between trait schizotypy, state auditory verbal hallucination (AVH) predisposition, distress and handedness for the expression of neurological soft signs (NSS), a neurodevelopmental vulnerability factor for psychosis. Cluster analysis formed schizotypy groups statistically across the dimensions captured by the SPQ. It was hypothesized that schizotypy and AVH predisposition would interact, resulting in significantly greater NSS. Psychological distress and handedness were hypothesized to be significant covariates, accounting for some variance in the expression of NSS between the groups. A sample of University students (n = 327) completed the Schizotypal Personality Questionnaire, Launay-Slade Hallucination Scale, General Health Questionnaire and the Neurological Evaluation Scale (NES). Cluster Analysis revealed four schizotypy groups. Distress was not a significant covariate in any analysis. As expected, those with high overall schizotypy and high AVH predisposition expressed significantly greater Motor-Coordination NSS compared to those with high schizotypy and low AVH predisposition. Within the Mixed Interpersonal and Cognitive-Perceptual Schizotypy cluster, those with low AVH predisposition expressed significantly more Motor-Coordination NSS than those with high AVH predisposition. These findings suggest motor coordination NSS are detectable in schizotypy, and AVH predisposition appears to interact with these traits. This study highlights the importance of considering both trait and subclinical state risk factors when investigating risk for psychosis

Dyslexia: Links with schizotypy and neurological soft signs

Abnormalities in language processing, psychological distress, and subtle neurodevelopmental features called neurological soft signs (NSS) are expressed by people with dyslexia and those scoring highly on schizotypy. We investigated whether the expression of NSS, distress, and schizotypy predicted dyslexia status. Participants (N = 96, 48 dyslexic) selected to be age and sex matched, completed the Schizotypal Personality Questionnaire, General Health Questionnaire, Neurological Evaluation Scale, and the National Adult Reading Test (NART; a measure of verbal intelligence). Dyslexia status was predicted by higher total NSS and disorganized schizotypy scores in the absence of NART. However, even with the inclusion of NART, disorganized schizotypy remained a significant predictor. The findings suggest that disorganized features of schizotypy could be a significant factor for those with dyslexia. Conversely, more attention needs to be given to developmental language disorders in those who score highly on schizotypy