Psychometrically-defined Schizotypy Research Articles

Olfactory threshold selectively predicts positive psychometric schizotypy

Olfactory impairment might be useful as a non-invasive pre-morbid biological marker of psychosis. People with schizophrenia show consistent impairments, but an association between olfaction and schizotypy in non-clinical populations is inconclusive and has been somewhat controversial. This is important as impairment in patients may be artefacts of antipsychotic medication. Meta-analyses indicate small effect sizes in non-clinical populations, suggesting prior negative studies may have been underpowered to demonstrate them.We measured olfaction and psychometrically-defined schizotypy in a sample of 739 non-clinical volunteers [mean age 23.1]. Subsets reported whether they had a history of mental illness in the family or smoked. We used (sniffin’ sticks) to measure threshold detection, discrimination and identification of odours. O-LIFE was used to measure schizotypy.Lower olfactory-threshold selectively predicted higher scores on the positive dimension, unusual experiences. This association was most evident in sub-groups reporting history of mental illness in the family and/or smoking. There was a weak trend for an association between identification and introvertive anhedonia and discrimination and cognitive disorganisation in those with a history of mental illness in the family.These data support the idea that olfaction merits further investigation as a biomarker for psychosis and that olfactory-threshold detection in particular has potential to selectively predict unusual experiences. Variability in previous studies may have been exacerbated by including different proportions of participants with history of mental illness in the family and/or smoking. We propose that non-clinical participants be stratified by these factors in future studies of olfaction and potentially any study that measures psychometric schizotypy.

Semantic coherence in psychometric schizotypy: An investigation using Latent Semantic Analysis

Technological advancements have led to the development of automated methods for assessing semantic coherence in psychiatric populations. Latent Semantic Analysis (LSA) is an automated method that has been used to quantify semantic coherence in schizophrenia-spectrum disorders. The current study examined whether: 1) Semantic coherence reductions extended to psychometrically-defined schizotypy and 2) Greater cognitive load further reduces semantic coherence. LSA was applied to responses generated during category fluency tasks in baseline and cognitive load conditions. Significant differences between schizotypy and non-schizotypy groups were not observed. Findings suggest that semantic coherence may be relatively preserved at this point on the schizophrenia-spectrum.

The Subjective-Objective Disjunction in Psychometrically-Defined Schizotypy: What it is and Why it is Important?

An interesting set of findings has emerged from the literature regarding schizotypy. Individuals with psychometric schizotypy self-report pathology in certain neuropsychological, affective experiential, expressive and olfactory abilities and subjective quality of life at levels between one and two standard deviations more severe than their non-schizotypal peers; a level often similar to that seen in chronic schizophrenia. Objectively however, individuals with psychometric schizotypy do not show concomitant impairments in these domains. This “subjective-objective” disjunction is remarkable in that samples are largely drawn from college settings; thus likely reflecting the healthiest individuals within the schizophrenia-spectrum. We propose that this disjunction can be conceptualized as a “cognitive bias”, and that it reflects a dysfunction in the systems underlying reasoning and self-evaluation. In this article, we lay out evidence underlying the subjective-objective disjunction and discuss potential methodological and psychological issues that may explain this phenomenon.

No apparent influence of psychometrically-defined schizotypy on orientation-dependent contextual modulation of visual contrast detection.

We investigated the relationship between psychometrically-defined schizotypy and the ability to detect a visual target pattern. Target detection is typically impaired by a surrounding pattern (context) with an orientation that is parallel to the target, relative to a surrounding pattern with an orientation that is orthogonal to the target (orientation-dependent contextual modulation). Based on reports that this effect is reduced in those with schizophrenia, we hypothesised that there would be a negative relationship between the relative score on psychometrically-defined schizotypy and the relative effect of orientation-dependent contextual modulation. We measured visual contrast detection thresholds and scores on the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) from a non-clinical sample (N = 100). Contrary to our hypothesis, we find an absence of a monotonic relationship between the relative magnitude of orientation-dependent contextual modulation of visual contrast detection and the relative score on any of the subscales of the O-LIFE. The apparent difference of this result with previous reports on those with schizophrenia suggests that orientation-dependent contextual modulation may be an informative condition in which schizophrenia and psychometrically-defined schizotypy are dissociated. However, further research is also required to clarify the strength of orientation-dependent contextual modulation in those with schizophrenia.

Motivational predictors of psychometrically-defined schizotypy in a non-clinical sample: Goal process representation, approach-avoid temperament, and aberrant salience

Patterns of problematic volitional control in schizotypal personality disorder pertaining to goal process representation (GPR), approach and avoidance temperament, and aberrant salience have not been widely investigated in emerging adults. The present study aimed to provide preliminary evidence for the utility of examining these three motivational constructs as predictors of high versus low levels of psychometrically-defined schizotypy in a non-clinic sample. When college students with high levels of self-reported schizotypy (n=88) were compared to those with low levels (n=87) by means of logistic regression, aberrant salience, avoidant temperament, and the self-criticism component of GPR together accounted for 51% of the variance in schizotypy group assignment. Higher score on these three motivational dimensions reflected a proclivity toward higher levels of schizotypy. The current findings justify the continued exploration of goal-related constructs as useful motivational elements in psychopathology research.

The normalities and abnormalities associated with speech in psychometrically-defined schizotypy

Speech deficits are thought to be an important feature of schizotypy — defined as the personality organization reflecting a putative liability for schizophrenia. There is reason to suspect that these deficits manifest as a function of limited cognitive resources. To evaluate this idea, we examined speech from individuals with psychometrically-defined schizotypy during a low cognitively-demanding task versus a relatively high cognitively-demanding task. A range of objective, computer-based measures of speech tapping speech production (silence, number and length of pauses, number and length of utterances), speech variability (global and local intonation and emphasis) and speech content (word fillers, idea density) were employed. Data for control (n=37) and schizotypy (n=39) groups were examined. Results did not confirm our hypotheses. While the cognitive-load task reduced speech expressivity for subjects as a group for most variables, the schizotypy group was not more pathological in speech characteristics compared to the control group. Interestingly, some aspects of speech in schizotypal versus control subjects were healthier under high cognitive load. Moreover, schizotypal subjects performed better, at a trend level, than controls on the cognitively demanding task. These findings hold important implications for our understanding of the neurocognitive architecture associated with the schizophrenia-spectrum. Of particular note concerns the apparent mismatch between self-reported schizotypal traits and objective performance, and the resiliency of speech under cognitive stress in persons with high levels of schizotypy.

Affecting coping: Does neurocognition predict approach and avoidant coping strategies within schizophrenia spectrum disorders?

According to various diathesis-stress models of schizophrenia, life stress plays a defining role in the onset and course of schizophrenia-spectrum disorders. In this regard, individual differences in coping strategies and affective traits, variables related to the management and experience of stress, may play a large role in susceptibility to the disorder and symptom exacerbation. Furthermore, it has been posited that cognitive deficits may limit an individuals' ability to effectively respond to stressful situations. We investigated the relationships between attention, immediate memory, trait negative affect (NA), trait positive affect (PA) and specific coping strategies within three groups: chronic schizophrenia patients (n=27), psychometrically-defined schizotypy (n=89), and schizotypy demographically-matched controls (n=26). As hypothesized affective traits displayed predictable relationships with specific coping strategies, such that NA was associated with the greater use of avoidant coping strategies within the schizophrenia and schizotypy group, while PA was associated with greater use of approach coping styles within all groups. The schizotypy group reported significantly higher levels of NA and also greater use of avoidant coping strategies than both the control and schizophrenia group. As expected group differences were found in trait affect, coping strategies, and cognitive functioning. Importantly, these group differences remained significant even when demographic variables were entered as covariates. Contrary to our expectations, cognitive functioning displayed only a few tenuous relationships with coping strategies within the schizophrenia and schizotypy groups. Overall, results support the notion that affective traits and not cognitive functioning is the best predictor of approach and avoidant coping strategies.

Kamin Blocking Is Associated with Reduced Medial-Frontal Gyrus Activation: Implications for Prediction Error Abnormality in Schizophrenia

The following study used 3-T functional magnetic resonance imaging (fMRI) to investigate the neural signature of Kamin blocking. Kamin blocking is an associative learning phenomenon seen where prior association of a stimulus (A) with an outcome blocks subsequent learning to an added stimulus (B) when both stimuli are later presented together (AB) with the same outcome. While there are a number of theoretical explanations of Kamin blocking, it is widely considered to exemplify the use of prediction error in learning, where learning occurs in proportion to the difference between expectation and outcome. In Kamin blocking as stimulus A fully predicts the outcome no prediction error is generated by the addition of stimulus B to form the compound stimulus AB, hence learning about it is “blocked”. Kamin blocking is disrupted in people with schizophrenia, their relatives and healthy individuals with high psychometrically-defined schizotypy. This disruption supports suggestions that abnormal prediction error is a core deficit that can help to explain the symptoms of schizophrenia. The present study tested 9 healthy volunteers on an f-MRI adaptation of Oades' “mouse in the house task”, the only task measuring Kamin blocking that shows disruption in schizophrenia patients that has been independently replicated. Participant's Kamin blocking scores were found to inversely correlate with Kamin-blocking-related activation within the prefrontal cortex, specifically the medial frontal gyrus. The medial frontal gyrus has been associated with the psychological construct of uncertainty, which we suggest is consistent with disrupted Kamin blocking and demonstrated in people with schizophrenia. These data suggest that the medial frontal gyrus merits further investigation as a potential locus of reduced Kamin blocking and abnormal prediction error in schizophrenia.

The role of atypical semantic activation and stress in odd speech: Implications for individuals with psychometrically defined schizotypy

BackgroundOdd speech is a cardinal symptom of schizophrenia; however, little is known about the mechanisms that lead to this construct in schizophrenia or schizotypy, the estimated 10% of the population who exhibit traits presumed to reflect genetic liability to schizophrenia. The lack of research concerning specific mechanisms of odd speech represents an important knowledge gap. Here, our primary aim was to examine how atypical semantic activation (ASA) and stress are related to odd speech in individuals with psychometrically-defined schizotypy. MethodsWe employed highly sensitive laboratory procedures to test whether significant differences in ASA exist between psychometric schizotypy (n = 45) and non-psychometric schizotypy (n = 26) groups. We also examined odd speech across four conditions that varied according to valence (pleasant, unpleasant) and arousal (high, low) and analyzed whether ASA mediates odd speech in schizotypy. ResultsThe psychometric schizotypy group demonstrated significantly increased ASA, in the large effect size range. They also demonstrated a significant increase in one odd speech condition and a trend level group by arousal interaction was observed. Our hypothesis that ASA mediates odd speech in schizotypy was not supported. ConclusionsIndividuals with psychometric schizotypy exhibit semantic activation that is similar to patients with schizophrenia, albeit in a milder form. This study also provides evidence that ASA is a potential endophenotype of schizophrenia. Future studies should further explore properties of odd speech and ASA. Suggested avenues include cognitive deficits, particularly working memory, exploring underlying mechanisms, and examining how these constructs affect individuals across the schizophrenia-spectrum.

Olfaction, “olfiction,” and the schizophrenia-spectrum: An updated meta-analysis on identification and acuity

Olfaction deficits in individuals with schizophrenia are well documented. A meta-analysis conducted nearly a dozen years ago on the topic revealed a deficit of a full standard deviation in magnitude compared to nonpatient controls. Recent efforts have been attempted to determine whether deficits in olfactory identification and acuity reflect a vulnerability marker of schizophrenia-spectrum pathology. To address this issue, the present study conducted a meta-analysis of 16 studies of individuals with schizotypy, defined in terms of a) “ultra-high risk” status, b) having an affected biological family member, or c) having extreme scores on a schizotypy questionnaire. We also conducted an updated meta-analysis of 40 studies of olfactory functioning in schizophrenia. Consistent with the prior meta-analysis, patients with schizophrenia showed impairments in olfaction identification on a full standard deviation in magnitude (d=−.99). Individuals with schizotypy showed much more subtle (d=−.24) differences in olfaction, though the effect sizes were higher for studies examining individuals at “ultra-high risk” (d=−.67) versus studies examining individuals with psychometrically-defined (d=−.14) schizotypy. Differences in olfactory acuity, relative to their respective control groups, were small for both the schizophrenia (d=−.45) and schizotypy (d=−.38) studies but were similar in magnitude. The present findings argue against the notion that deficits in olfaction identification are a vulnerability marker of schizophrenia. Suggestions for future research are recommended.

Understanding Constricted Affect in Schizotypy Through Computerized Prosodic Analysis

Constricted affect (CA) is a cardinal negative symptom of schizophrenia-spectrum disorders. It is unclear whether behaviorally-defined CA occurs in individuals with schizotypy-those with the personality organization reflective of schizophrenia liability. Moreover, it is unclear whether CA contributes to real world dysfunction in this population. The present study employed computerized prosodic analysis of natural speech procured during a laboratory procedure. Subjects were 89 individuals with psychometrically-defined schizotypy and 26 controls. Groups did not differ in any of the prosody measures examined here. Within the schizotypy group, increased prosodic expression was associated with positive schizotypy traits while decreased prosodic expression was associated with negative schizotypy traits. Prosodic deficits were significantly associated with reduced prosocial behaviors (e.g., talking with friends) but were not associated with subjective social satisfaction. Prosodic deficits characterize a subset of individuals with schizotypy who show a schizoid-like reduction in social behaviors without a concomitant reduction in social satisfaction.

Cannabis and psychometrically-defined schizotypy: Use, problems and treatment considerations

Cannabis use is associated with onset of psychosis in individuals vulnerable for developing schizophrenia-spectrum disorders. The present study addressed three knowledge gaps pertaining to this issue: 1) clarifying the incidence of cannabis use in schizotypal individuals, 2) examining how cannabis use is related to psychosocial and physiological problems in schizotypy and interest in treatment, and 3) examining how cannabis use is associated with positive, negative and disorganization features of schizotypy. Scores from a measure of schizotypal traits were used to trichotomize 1665 young adults into schizotypy (top 5% of scorers), non-schizotypy (bottom 50% of scorers) and “unconventional” (scorers within the 50th to 85th percentile) groups. Nearly a quarter of the schizotypy group endorsed cannabis use at least weekly, a rate nearly two to four times that of the other groups. The schizotypy group also reported a much greater frequency of cannabis-related problems compared to the other groups. Despite this, interest in treatment for cannabis use in the schizotypy group was not elevated. Interestingly, 85% of individuals in the schizotypy group reported interest in psychological/psychiatric treatment more generally. Cannabis use was not associated with abnormal patterns of positive or disorganized schizotypy traits in the schizotypy group relative to the other groups. However, cannabis use was associated with lower severity of negative traits. Implications of these results are discussed.

Affective reactivity of speech disturbances in schizotypy

Speech disturbances (SD) are a pernicious symptom of schizophrenia that increase when negative emotion is elicited. This increase is referred to as affective reactivity (AR). Although considerable research has examined SD in schizophrenia, few studies have investigated this symptom in individuals at risk for the disorder, who demonstrate schizophrenia-like, or schizotypic, traits. In the present study, we examined: (1) SD severity in schizotypy, (2) how SD varies as a function of stress reactivity in schizotypy, and (3) the relationship between SD/AR with Quality of Life (QOL). Individuals with psychometrically-defined schizotypy ( n = 83) and controls ( n = 22) completed a laboratory procedure in which they produced speech while viewing pleasant and stressful photographs. This speech was analyzed for subtle speech disorder using a well-validated measure. We found that the schizotypy group demonstrated significant increases in SD across both baseline and stressful conditions compared to the control group. AR was not significantly different between the groups. Within the schizotypy group, severity of disorganized schizotypy symptoms was associated with high levels of SD and AR while interpersonal schizotypy was associated with low levels of SD and AR. AR was also related to increased objective QOL in the schizotypy group. This study highlights the role of stress reactivity across the schizophrenia-spectrum. Moreover, the incongruous relationships between disorganized and interpersonal symptoms with SD underscore the marked heterogeneity in processes across schizotypy.

Olfactory identification performance in individuals with psychometrically-defined schizotypy

While deficits in olfaction have been well documented in individuals with schizophrenia, less research has focused on olfactory identification performance in psychometrically-defined schizotypy. The Abbreviated Schizotypal Personality Questionnaire was used to define two groups of 26 individuals (62% female) reporting high and average levels of schizotypy. Overall group differences on the Brief Smell Identification Test did not approach statistical significance, and this finding did not differ within either sex. The findings may reflect either the abbreviated nature of the measures used, or a lack of reliable olfactory performance differences in schizotypy.