The nature of schizotypy among multigenerational multiplex schizophrenia families

Identification of endophenotypes (Gottesman & Gould, 2003; Gottesman & Shields, 1972) that genetically correlate with schizophrenia and are genetically homogeneous is an important strategy for detecting genes that affect schizophrenia risk. Symptoms of schizotypy may familially correlate with schizophrenia; however, there are critical limitations of the current literature concerning this association. The present study examined the genetic architecture and genetic associations between schizotypy and schizophrenia among multigenerational, multiplex schizophrenia families. Genetic schizotypy factor scales were developed that genetically correlated with schizophrenia, although some relations were unexpected in direction suggesting minimization of "psychotic-like" symptoms. These genetic schizotypy factor scales did not genetically correlate with major depressive disorder or substance dependence indicating specificity to schizophrenia. The results highlight the possibility of significant response bias in schizophrenia families, particularly among close relatives, and suggest an important consideration when acquiring self-report information. This is a topic that deserves future study as the origins of this putative bias in relatives are unclear. In addition, the results support the identification of genetic schizotypy factors as a promising technique for maximizing genetic correlation of endophenotypes with schizophrenia.     

Emotion processing deficits in the different dimensions of psychometric schizotypy

Schizotypy refers to a personality structure indicating “proneness” to schizophrenia. Around 10% of the general population has increased schizotypal traits, they also share other core features with schizophrenia and are thus at heightened risk for developing schizophrenia and spectrum disorders. A key aspect in schizophrenia‐spectrum pathology is the impairment observed in emotion‐related processes. This review summarizes findings on impairments related to central aspects of emotional processes, such as emotional disposition, alexithymia, facial affect recognition and speech prosody, in high schizotypal individuals in the general population. Although the studies in the field are not numerous, the current findings indicate that all these aspects of emotional processing are deficient in psychometric schizotypy, in accordance to the schizophrenia‐spectrum literature. A disturbed frontotemporal neural network seems to be the critical link between these impairments, schizotypy and schizophrenia. The limitations of the current studies and suggestions for future research are discussed.     

Schizotypy and hemisphericity

There is considerable evidence that schizophrenia spectrum disorders are associated with a variety of abnormal asymmetries of brain structure, function, and behavior. Schizotypy is a personality trait dimension extending into the normal range, which at its extreme, is associated with a vulnerability to schizophrenia spectrum disorders. Schizotypy in the normal range is also associated with a variety of neurobiological characteristics associated with schizophrenia spectrum disorders, including abnormal brain and behavioral asymmetries. Previous studies have suggested that normal schizotypy (as well as belief in the paranormal) is associated with an increased reliance on the right hemisphere in a variety of tasks. Hemisphericity is a trait-related characteristic preference for the cognitive mode of one or the other cerebral hemispheres, putatively related to hemispheric activation asymmetry. A sample of 256 undergraduates was administered five schizotypy scales, as well as three hemisphericity measures. Higher schizotypy scores were associated with an increase in right hemisphericity and a decrease in integrated hemisphericity. Although the construct of hemisphericity has been criticized, there is evidence to suggest that questionnaire and eye movement measures of hemisphericity may yet have construct validity, and further research on hemisphericity may be warranted.     

Schizotypy: An Organizing Framework for Schizophrenia Research

ABSTRACT— Schizophrenia is the most devastating form of psychopathology known to humankind, and it has been slow to yield clues to its origins. Meehl's (1962, 1990) model detailed the nature of the latent liability for schizophrenia known as schizotypy and provided a major organizing function for research on schizophrenia. The schizotypy model integrates genetic and environmental contributions to liability as well as accounting for a range of clinical outcomes, all deriving from a genuine liability for the illness. Schizotypy, as a latent personality organization that harbors the liability for schizophrenia, provides a framework for detecting fundamental features of liability to schizophrenia prior to the onset of clinical illness. The schizotypy model is reviewed, the strategic benefits of it are discussed, and methods for detecting schizotypy are presented. A focus on perceptual aberrations—a schizotypic feature—in individuals unaffected by schizophrenia has yielded valuable clues to preclinical disturbances in neurocognitive processes, risk for schizophrenia among biological relatives, and genomic substrates, all of which are of interest to schizophrenia researchers.     

On "risk" and reward: investigating state anhedonia in psychometrically defined schizotypy and schizophrenia

Anhedonia, defined as dysfunction in the experience of pleasant emotions, is a hallmark symptom of the schizophrenia spectrum. Of interest, it is well documented that patients with schizophrenia, at least as a group, do not show reductions in their state experience of pleasant stimuli. However, there is emerging evidence to suggest that individuals with schizotypy--defined as the personality organization reflecting the latent vulnerability for schizophrenia--do show these state deficits. This is paradoxical in that schizophrenia reflects a more pathological state in virtually every conceivable domain as compared with schizotypy. The present study examined self-reported affective reactions to neutral-, bad-, and good-valenced stimuli in individuals with psychometrically defined schizotypy and schizophrenia. Two separate control groups were also included, comprising psychometrically defined controls and stable outpatients with affective disorders. With no exceptions, the schizotypy group reported significantly less pleasant affect for each of the three conditions than each of the other groups. Conversely, the schizophrenia group did not statistically differ from the control groups for any of the conditions. Within both the schizotypy and schizophrenia groups, severity of negative symptoms/traits was associated with less pleasant report. We found that individuals with prominent negative symptoms and traits from the schizophrenia and schizotypy groups resembled each other in terms of state anhedonia. The present findings did not appear to reflect comorbid depression or anxiety. Our discussion centers on this apparent paradox in the schizophrenia spectrum--that individuals with schizotypy exhibit state anhedonia, whereas patients with schizophrenia do not.     

P50 sensory gating deficits in schizotypy

Sensory gating is the ability to filter out irrelevant stimuli from the environment. Individuals with schizophrenia consistently demonstrate deficits in this ability leading to sensory overload and cognitive fragmentation. This dysfunction has also been found in schizotypy, which is defined as a manifestation of nonclinical symptoms qualitatively similar to those found in schizophrenia. In the present study, auditory sensory gating was assessed in healthy individuals by testing the attenuation of the P50 event-related potential. The degree of suppression was then correlated with schizotypy by using the O-LIFE questionnaire. Relative to the low-scoring individuals, P50 suppression was significantly reduced in those with high levels of schizotypy. Furthermore, the degree of deficit in P50 gating correlated with both cognitive disorganisation and impulsive nonconformity dimensions of schizotypy. These results suggest that schizotypal individuals may have early sensory gating deficits similar to schizophrenia patients, especially if they display a disorganised or impulsive profile. As they do not exhibit overt psychotic symptoms, it is likely that such deficits represent an underlying core cognitive dysfunction within the schizophrenia spectrum.     

Extreme elemental processing in a high schizotypy population: Relation to cognitive deficits

The cognitive deficits observed in schizophrenia have been characterized as a failure to utilize task-setting information to guide behaviour, especially in situations in which there is response conflict. Recently, we have provided support for this account; high schizotypy individuals demonstrated inferior biconditional discrimination performance compared to low scorers, but were not impaired on a simple discrimination that did not require the use of task-setting cues. These results may, however, also be explained by the way in which individuals with high schizotypy process stimulus compounds. Here, we examine the initial approaches to solving biconditional and control discrimination tasks of participants with high and low schizotypy scores. In particular, we focus on performance during the first block of training trials to capture processing style before the acquisition of the discrimination tasks. Participants scoring highly on the introvertive anhedonia subscale (which has been allied to the negative and cognitive symptoms of schizophrenia) demonstrated better biconditional performance during the first block of training trials than did low-schizotypy individuals, consistent with a highly elemental approach to stimulus processing. Subsequent recognition tests confirmed this analysis demonstrating that the pattern of performance observed in participants with high schizotypy was associated with a failure to discriminate conjunctions of items that had been seen before from those that had not. These results suggest that the negative/cognitive symptoms of schizophrenia may reflect an extreme bias towards elemental, as opposed to configural, processing of stimulus conjunctions.     

Response inhibition and interference control: Effects of schizophrenia,genetic risk,and schizotypy

The ability to inhibit inappropriate responses and suppress irrelevant information is a core feature of executive control. In this study, we provide a detailed analysis of prepotent response inhibition and interference in patients with schizophrenia. To further test the role of genetic factors and subclinical schizophrenia‐like traits, we additionally studied clinically unaffected, first‐degree relatives of schizophrenia patients and assessed dimensions of schizotypy in both relatives and healthy controls. Inhibition and interference control were assessed using a battery comprising the antisaccade, Stroop, stop signal, go/no‐go, flanker, and Simon tasks. Schizophrenia patients differed from both relatives and controls in making more errors on the antisaccade task and having longer response times on the Stroop task, especially the incongruent condition. Patients also had general, that is, condition independent, increases in reaction times on the go/no‐go and flanker tasks and made more errors on the flanker and Simon tasks, suggesting general performance impairments independent of inhibitory demand. Relatives were characterized by hypometric antisaccade amplitude gain despite normal prosaccades, suggesting a selective deficit in non‐standard sensorimotor transformations. Schizotypy was correlated with inhibitory performance across a number of tasks in both relatives and controls. Generally, these effects were independent of verbal intelligence levels. Overall, the findings point to rather selective impairments of inhibitory control in the schizophrenia spectrum and confirm a previously observed deficit in antisaccade spatial accuracy as an endophenotype of schizophrenia.     

Deeper into the schizotypy taxon: on the robust nature of maximum covariance analysis

Prior research has suggested that the latent structure of the schizotypy construct (P. E. Meehl, 1990) may be qualitative in nature and have a low base rate (L. Korfine & M. F. Lenzenweger, 1995; M. F. Lenzenweger & L. Korfine, 1992). These studies relied on the application of maximum covariance analysis (MAXCOV) to 8 true-false format items from a schizotypy measure. The current study sought to examine the robustness of those prior findings through MAXCOV analysis of fully quantitative measures of schizotypy. Measures of perceptual aberration, magical ideation, and referential thinking were analyzed using MAXCOV in a sample of 429 persons. The results of these analyses strongly support a latent taxonic structure for schizotypy and a low base rate for the schizotypy taxon. Furthermore, the members of the putative taxon reveal an increased level of deviance on a psychometric measure known to be associated with schizophrenia liability. The possibility that the dichotomous item format of those items analyzed previously with MAXCOV lead to spurious pseudotaxonicity is greatly diminished in light of these results.     

Finding the "genuine" schizotype: a model and method for resolving heterogeneity in performance on laboratory measures in experimental psychopathology research

Heterogeneity in the performance of persons affected with schizophrenia or schizotypic psychopathology on various laboratory tasks has long been recognized, both for its consistency across tasks and studies and for the massive methodological and substantive challenges it poses for experimental psychopathology, genetic, and other investigations. Traditional multivariate techniques, such as factor analysis, discriminant function analysis, and cluster analysis, have all been deemed inadequate for resolving heterogeneity, because of one or another statistical limitation. Here, an objective statistical approach based on a formal statistical model that uses the ubiquitous and well-developed expectation-maximization (EM) algorithm (A. P. Dempster, N. M. Laird, & D. B. Rubin, 1977) is presented, which enables one effectively to partition a group of experimental subjects, in this case identified initially using the well-known Perceptual Aberration Scale (L. J. Chapman, J. P. Chapman, & M. L. Raulin, 1978), in a manner that reduces heterogeneity and allows for the separation of what are termed genuine and false-positive schizotypes. The validity of the parsing strategy was supported by reference to other laboratory indexes of relevance to schizophrenia and schizotypy that were not included in the initial EM-based analyses. The potential utility of this approach is discussed with reference to future schizophrenia and schizotypy research.     

Neuropsychological differentiation of adaptive creativity and schizotypal cognition

Both creativity and schizophrenia-spectrum disorders have been associated with activation of remote semantic concepts, but this activation results in innovative output in one case and communication disturbances in the other. The present study examined the relationship between monitoring semantic information (which relies on executive brain function), creativity, and characteristics of schizotypy in an undergraduate population. Results indicate that executive function differentiates the use of semantic information in creativity and schizotypy. Specification of the balance between executive monitoring and activation of semantic information is important for determining how communication disturbances manifest, and for the measurement of creativity and schizotypy in the general population.     

Confirming the latent structure and base rate of schizotypy: a taxometric analysis.

Meehl's (1962, 1990) model of schizotypy and the development of schizophrenia implies that the structure of liability for schizophrenia is dichotomous and that a "schizogene" determines membership in a latent class, or taxon (Meehl & Golden, 1982). The authors sought to determine the latent structure and base rate of schizotypy. They applied Meehl's (1973; Meehl & Golden, 1982) MAXCOV-HITMAX taxometric analytic procedures to a subset of items from the Perceptual Aberration Scale (PAS; Chapman, Chapman, & Raulin, 1978), a prominent psychometric index of schizotypy, derived from a randomly ascertained nonclinical university sample (N = 1,093). The results, in accordance with Meehl's conjectures, strongly suggest that schizotypy, as assessed by the PAS, is taxonic at the latent level with a general population taxon base rate of approximately .10.     

Familial prevalence and coaggregation of schizotypy indicators: a multitrait family study

Schizophrenic probands (n = 17), their first-degree relatives (n = 61), and medically and psychiatrically screened normal control subjects (n = 18) were studied with structured interviews for DSM-III Axis I disorders and schizotypal personality disorder, questionnaire measures of schizotypy, measures of smooth-pursuit eye movement dysfunction, and attention dysfunction. Schizophrenic subjects scored abnormally on essentially all measures. Relatives differed significantly from control subjects on most measures. Correlational analyses indicate that many characteristics tested in these measures run together in families. The data are consistent with the hypothesis that a single vulnerability dimension or typology, presumably in part genetically transmitted, may account for phenotypically distinct abnormalities. These traits, taken together, may have joint usefulness for identifying persons with a predisposition to schizophrenia.     

Jumping to Conclusions bias,BADE and Feedback Sensitivity in schizophrenia and schizotypy

Several studies about schizophrenia have shown a cognitive bias named “Jumping to Conclusions” (JTC), defined as a decision made quickly on the basis of little evidence that occurs in these patients when performing probabilistic reasoning paradigms. The main objective of this study is to compare JTC bias and BADE (Bias Against Disconfirmatory Evidence) in patients with schizophrenia vs. participants with high/low schizotypy to understand the underlying mechanism of these cognitive biases. Probabilistic reasoning was assessed using a modified version of Drawing to Decision task. In addition to the traditional parameters of this task (Plausibility Rating (PR), Draws to Decision (DTD), BADE) we also calculated new parameters, overall accuracy and one named Feedback Sensitivity (FS) which lower scores shows greater use of feedback. The results of the study suggest a context effect: in the cued condition, there were not main differences between groups. In the uncued condition, we found higher JTC bias at stage 1 for patients. At the same time, PR at first stages related positively with Feedback Sensitivity and negatively with accuracy for patients and high schizotypy participants (high confidence is associated with worse performance and lower feedback use). BADE seems unrelated to JTC bias and FS. The results are discussed in terms of JTC like as a clinical bias and whether patients with schizophrenia are less able to use feedback.     

Intact emotion–cognition interaction in schizophrenia patients and first-degree relatives: Evidence from an emotional antisaccade task

Schizophrenia patients have deficits in cognitive control as well as in a number of emotional domains. The antisaccade task is a measure of cognitive control that requires the inhibition of a reflex-like eye movement to a peripheral stimulus. Antisaccade performance has been shown to be modulated by the emotional content of the peripheral stimuli, with emotional stimuli leading to higher error rates than neutral stimuli, reflecting an implicit emotion processing effect. The aim of the present study was to investigate the impact on antisaccade performance of threat-related emotional facial stimuli in schizophrenia patients, first-degree relatives of schizophrenia patients and healthy controls. Fifteen patients, 22 relatives and 26 controls, matched for gender, age and verbal intelligence, carried out an antisaccade task with pictures of faces displaying disgusted, fearful and neutral expressions as peripheral stimuli. We observed higher antisaccade error rates in schizophrenia patients compared to first-degree relatives and controls. Relatives and controls did not differ significantly from each other. Antisaccade error rate was influenced by the emotional nature of the stimuli: participants had higher antisaccade error rates in response to fearful faces compared to neutral and disgusted faces. As this emotional influence on cognitive control did not differ between groups we conclude that implicit processing of emotional faces is intact in patients with schizophrenia and those at risk for the illness.     

Schizotypy and mental health amongst poets, visual artists, and mathematicians

Many researchers have found evidence of an association between creativity and the predisposition to mental illness. However, a number of questions remain unanswered. First, it is not clear whether healthy creatives have a milder loading on schizotypal traits than people who suffer serious psychopathology, or whether they have an equal loading, but other mediating characteristics. Second, most of the existing research has concentrated on artistic creativity, and the position of other creative domains is not yet clear. The present study compares schizotypy profiles using the O-LIFE inventory in a large sample of poets, artists, mathematicians, the general population, and psychiatric patients. Poets and artists have levels of unusual experiences that are higher than controls, and as high as schizophrenia patients. However, they are relatively low on the dimension of introvertive anhedonia. Mathematicians are lower than controls on unusual experiences. The results suggest that artistic creatives and psychiatric patients share a tendency to unusual ideas and experiences, but creative groups are distinguished by the absence of anhedonia and avolition. Moreover, different domains of creativity require different cognitive profiles, with poetry and art associated with divergent thinking, schizophrenia and affective disorder, and mathematics associated with convergent thinking and autism.     

The backward masking red light effect in schizophrenia: relationship to clinical features and neurocognitive performance

The "backward masking red light effect" involves a change in visual backward masking performance with a red (compared with a green or gray) background that is in the opposite direction relative to nonpsychiatric controls. This effect has been previously reported in individuals with schizophrenia, their first-degree relatives, and a schizotypy sample. The current study provides the first examination of the relationship of this effect with clinical and neurocognitive measures in a new sample of higher functioning patients with schizophrenia. A location backward masking by pattern task was administered to 16 outpatients with schizophrenia and 21 nonpsychiatric controls. The task was presented on red, green, and gray backgrounds. There was a significant group by color interaction at the 60-ms stimulus onset asynchrony: Participants with schizophrenia tended to decrease accuracy with a red (compared with a gray) background, whereas controls tended to increase accuracy. This interaction remained significant after covarying for baseline (gray) backward masking accuracy. In the schizophrenia patients, a decrease in backward masking accuracy to the red background was correlated with more negative symptoms, lower estimated premorbid IQ, and greater color-word Stroop interference but was not related to positive or disorganized symptoms, age of onset, duration of illness, digit symbol coding performance, or baseline (gray) backward masking accuracy. In contrast, there was no relationship between the red light change score and any of the neurocognitive variables in the control group.     

Schizotypy and sustained attention: confirming evidence from an adult community sample

Sustained attention deficits represent one of the most robust findings in the study of schizophrenia and schizotypy. However, very little is known about the nature of sustained attention performance and schizotypy in the general adult population. The present study assessed sustained attention performance in a large, normative adult community sample (N = 305) with no history of psychosis using the Continuous Performance Test-identical pairs version (CPT-IP). Associations between overall CPT-IP performance and schizotypal personality disorder features, controlling for the effects of age, sex, and educational level, revealed diminished sensitivity (d', discriminability), and increased random errors were related to increased reality distortion features. These data, drawn from a general population sample, provided support for overall sustained attention deficits as an endophenotype for schizophrenia liability.     

Psychometric schizotypy and motor performance

Motor abnormalities have long been a focus in discussions of schizophrenia. The present study used a newly developed line drawing task to examine fine motor performance and psychometrically assessed schizotypy in a large, randomly ascertained sample of young adults (N = 120) with no history of psychosis. Poor motor performance on the line drawing task, indexed by root-mean-square error (RMS), was significantly related to 4 separate psychometric measures of schizotypy in the overall sample. The psychometric schizotypy-RMS association remained significant for 2 of the schizotypy measures even when the effects of intellectual functioning, mental state factors, and sustained attention were statistically controlled in a regression analysis. The status of the line drawing index as a schizophrenia liability measure is discussed.     

An investigation of schizotypy in injecting amphetamine users

A fully dimensional view of psychiatric disorder conceptualises schizotypy as both a continuous personality trait and an underlying vulnerability to the development of psychotic illness. Such a model would predict that the structure of schizotypal traits would closely parallel the structure of schizophrenia or psychosis. This was investigated in injecting amphetamine users (N = 322), a clinical population who have high rates of acute psychotic episodes and subclinical schizotypal experiences. Schizotypy was assessed using the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE), and psychotic symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS). Using confirmatory factor analysis, O-LIFE subscale scores were mapped onto latent variables with their more clinical counterparts from the BPRS. A four-factor model comprising positive schizotypy, disorganisation, negative schizotypy, and disinhibition provided the best model fit, consistent with prior research into the structure of schizotypy. The model provided a good fit to the data, lending support to the theory that schizotypy and psychotic symptoms map onto common underlying dimensions.