Associations between schizotypal features and indicators of neurological and morphological abnormalities

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.

Neurological Soft Signs (NSS) in Census-Based, Decade-Adjusted Healthy Adults, 20 to >70 Years of Age

Neurological soft signs (NSS) represent minor neurological features and have been widely studied in psychiatric disease. The assessment is easily performed. Quantity and quality may provide useful information concerning the disease course. Mostly, NSS scores differ significantly between patients and controls. However, literature does not give reference values. In this pilot study, we recruited 120 healthy women and men to build a cross-sectional, census-based sample of healthy individuals, aged 20 to >70 years, subdivided in 10-year blocks for a close approach to the human lifeline. Testing for NSS and neurocognitive functioning was performed following the exclusion of mental and severe physical illness. NSS scores increased significantly between ages 50+ and 60+, which was primarily accountable to motor signs. Gender and cognitive functioning were not related to changes of scores. Although the number of individuals is small, study results may lay a foundation for further validation of NSS in healthy individuals.

Attenuated Post-Movement Beta Rebound Associated With Schizotypal Features in Healthy People

INTRODUCTION

Schizophrenia and schizotypal personality disorder (SPD) lie on a single spectrum of mental illness and converging evidence suggests similarities in the etiology of the 2 conditions. However, schizotypy is a heterogeneous facet of personality in the healthy population and so may be seen as a bridge between health and mental illness. Neural evidence for such a continuity would have implications for the characterization and treatment of schizophrenia. Based on our previous work identifying a relationship between symptomology in schizophrenia and abnormal movement-induced electrophysiological response (the post-movement beta rebound [PMBR]), we predicted that if subclinical schizotypy arises from similar neural mechanisms to schizophrenia, schizotypy in healthy individuals would be associated with reduced PMBR.

METHODS

One-hundred sixteen participants completed a visuomotor task while their neural activity was recorded by magnetoencephalography. Partial correlations were computed between a measure of PMBR extracted from left primary motor cortex and scores on the Schizotypal Personality Questionnaire (SPQ), a self-report measure of schizotypal personality. Correlations between PMBR and SPQ factor scores measuring cognitive-perceptual, interpersonal and disorganization dimensions of schizotypy were also computed. Effects of site, age, and sex were controlled for.

RESULTS

We found a significant negative correlation between total SPQ score and PMBR. This was most strongly mediated by variance shared between interpersonal and disorganization factor scores.

CONCLUSION

These findings indicate a continuum of neural deficit between schizotypy and schizophrenia, with diminution of PMBR, previously reported in schizophrenia, also measurable in individuals with schizotypal features, particularly disorganization and impaired interpersonal relations.

Neurological soft signs in familial and sporadic schizophrenia

OBJECTIVE

Neurological soft signs (NSS) are a group of minor non-localizable neurological abnormalities found more often in patients with schizophrenia. The aim of the current study was investigate whether there is any difference in their manifestation in familial vs. sporadic schizophrenia.

MATERIAL AND METHODS

The study sample included 120 patients suffering from schizophrenia according to DSM-5 (71 males and 49 females; aged 32.79 ± 11.11 years old) and 110 normal controls (57 males and 53 females; aged 33.38 ± 10.14 years old). The assessment included the Neurological Evaluation Scale (NES) and the detailed investigation family history. The statistical analysis included exploratory Analysis of Covariance.

RESULTS

The results of the current study suggest that NSS are more frequent in familial cases of schizophrenia and are even more pronounced in cases with family history of psychosis in either first or second degree relatives.

DISCUSSION

Overall the results suggest the presence of a spectrum of increasing severity from healthy controls to sporadic cases, to cases with non-psychotic family history and eventually to cases with psychotic family history, rather than a categorical distribution.

Social anhedonia and gamma band abnormalities as a composite/multivariate endophenotype for schizophrenia: a dense array EEG study

AIM

Social anhedonia and gamma band oscillations are proposed as a promising endophenotype for schizophrenia (SZ). The aim was to assess whether social anhedonia and spontaneous gamma band oscillations could be used as multivariate/composite endophenotypic measures for SZ.

METHODS

Sixty consented subjects, of which 20 remitted SZ patients, 20 unaffected siblings of patients with schizophrenia (US) and 20 healthy controls (HC) were recruited for the study. The Revised Social Anhedonia Scale, Temporal Experience of Pleasure Scale and the Schizotypal Personality Questionnaire assessed social anhedonia, temporal experience of pleasure and schizotypal features. All participants underwent awake, resting state 192-channel dense array electroencephalographic recording. Gamma spectral power and coherence were calculated. We performed chi-square test, one-way analysis of variance, Pearsons correlation coefficient and step-by-step linear discriminant functional analysis.

RESULTS

Social anhedonia was significantly higher and anticipatory aspects of pleasure were significantly lower in both SZ and US compared with HC. US scored significantly higher than HC in the Schizotypal Personality Questionnaire. Spectral power of high gamma band (>70 Hz) was significantly lower over the right temporo-parietal and midline regions in both SZ and US than HC. We accurately classified (85%) three groups when social anhedonia, high gamma band spectral power of midline, right frontal and right fronto-temporal interhemispheric gamma coherence were considered as composite measures rather than each variable representing independently.

CONCLUSION

We propose region-specific high gamma spectral 'power and coherence' and social anhedonia as composite/multivariate measures could be a useful measure in distinguishing schizophrenia patients and unaffected siblings from healthy controls.

Prevalence and correlates of neurological soft signs in healthy controls without family history of any mental disorder: A neurodevelopmental variation rather than a specific risk factor?

OBJECTIVE

Neurological soft signs (NSS) are a group of minor non-localizable neurological abnormalities found more often in patients with schizophrenia and other mental disorders. The aim of the current study was to investigate their prevalence and correlates in healthy controls without family history of any mental disorder.

MATERIAL AND METHODS

The study sample included 122 normal subjects (66 males and 56 females; aged 32.89 ± 9.91 years old). The assessment included the Neurological Evaluation Scale (NES), and a number of scales assessing the subthreshold symptoms (MADRS, STAI) and functioning (GAF). Data on a number of socio-demographic variables were also gathered. The statistical analysis included the development of basic statistics tables and the calculation of Pearson correlation coefficients.

RESULTS

The results of the current study suggest that more than half of the study sample manifested at least one NSS and approximately 5% more than four. Still, the reported prevalence and NES scores are lower form those reported in the literature probably because of the carefully selected study sample. There were no significant correlations between NSS and any socio-demographic or clinical variable.

DISCUSSION

The current study is the first to study NSS in subjects without family history of any mental disorder and reports the presence of frequent silent neurodevelopmental events in the general population, probably in the form of a neurodevelopmental variation and possibly a weak generic rather than specific risk factor.

Schizotypal and affective traits in the offspring of antenatally depressed mothers - Relationship to family history of psychosis in the Northern Finland 1966 Birth Cohort

BACKGROUND

Maternal depression is relatively common during pregnancy. However, follow-ups of the adult offspring of antenatally depressed mothers are scarce. Previously we found the risk of schizophrenia to be higher in the adult offspring with antenatally depressed mothers and parents with psychosis than in subjects with only one or neither of these risk factors. The aim was to study whether the risk of schizotypal or affective traits differ among adult offspring with antenatally depressed mothers with or without a parental history of psychosis when compared with offspring without antenatally depressed mothers and without parental psychosis.

METHODS

In the general population-based Northern Finland 1966 Birth Cohort (NFBC 1966), the mothers of the cohort members were asked at mid-gestation whether they felt depressed. Parental psychosis (Familial Risk, FR) was detected using the Finnish Care Register for Health Care. In the 31-year field study, seven psychometric questionnaires surveyed schizotypal and affective traits in the offspring. The final sample included 4928 individuals (2203 males).

RESULTS

There were no statistically significant differences in mean scores on the schizotypal and affective scales between offspring with and without antenatally depressed mothers, or between subjects with and without parental psychosis. The scores were not highest in the subjects with both maternal antenatal depressed mood and FR.

CONCLUSION

Surprisingly, maternal depressed mood during pregnancy was unlikely to increase the risk of schizotypy or affective traits in adult offspring, and not even with parental psychosis (FR) in this general population-based birth cohort with about 5000 subjects.

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.

Association between neurological soft signs, temperament and character in patients with schizophrenia and non-psychotic relatives

The heritability of schizophrenia and most personality traits has been well established, but the role of personality in susceptibility to schizophrenia remains uncertain. The aim of this study was to test for an association between personality traits and Neurological Soft Signs (NSS), a well-known biological marker of schizophrenia, in non-psychotic relatives of patients with schizophrenia. For this purpose, we evaluated the NSS scale and personality measured by the Temperament and Character inventory (TCI-R) in three groups of subjects: 29 patients with schizophrenia, 24 unaffected relatives and 37 controls. The results showed that patients with schizophrenia were more asocial (higher harm avoidance and lower reward dependence), more perseverative (higher persistence), and more schizotypal (lower self-directedness and cooperativeness, higher self-transcendence). The unaffected relatives showed higher harm avoidance, lower self-directedness and cooperativeness than the healthy controls. Higher NSS scores and sub-scores were found in patients and non-psychotic relatives compared with the controls. Among all the patients, total NSS scores were positively correlated with harm avoidance but negatively correlated with novelty seeking and persistence. Total NSS were also correlated with low scores on self-directedness and cooperativeness, which are indicators of personality disorder. Our results show that susceptibility to NSS and to schizophrenia are both related to individual differences in the temperament and character features in non-psychotic relatives of patients with schizophrenia. High harm avoidance, low persistence, low self-directedness and low cooperativeness contribute to both the risk of NSS and schizophrenia. These findings highlight the value of using both assessments to study high risk populations.

Luria revisited: complex motor phenomena in first episode schizophrenia and schizophrenia spectrum disorders

Patients with schizophrenia frequently exhibit motor deficits. However, to date, there are no studies comparing motor performance in first episode patients with schizophrenia and schizophrenia spectrum disorders (SSD; e.g. schizoaffective and brief psychosis). Participants comprised 57 first episode patients with schizophrenia, 32 first episode patients with SSD, and 51 healthy controls who underwent neuropsychological testing based on Luria׳s systematic approach, including the following tests on complex motor sequencing: the Fist-Edge-Palm (FEP) test and the bimanual probe (BP). Schizophrenia patients performed worse than SSD patients in FEP and BP, and both patient groups showed decreased scores compared to healthy controls. Furthermore, we found that a higher proportion of schizophrenia cases failed to correct their motor performance and needed external error correction, while SSD cases exhibited a higher proportion of self-correction in FEP and in BP. Lack of insight and poor executive functioning correlated with motor performance in schizophrenia, while impulse control and difficulties in abstract thinking were related to motor performance in schizophrenia spectrum disorder. Thus, psychomotor impairments appear already in first episode patients with schizophrenia and differ from impairments in SSD. Especially the inability to self-correct errors may be characteristic of schizophrenia, suggesting that impairments in error monitoring are related to psychomotor dysfunction in schizophrenia.

Evaluation of spontaneous dense array gamma oscillatory activity and minor physical anomalies as a composite neurodevelopmental endophenotype in schizophrenia

OBJECTIVE

Minor physical anomalies (MPAs) and gamma oscillatory activity have been proposed as associated endophenotypes in schizophrenia. Combining these endophenotypes to create a composite endophenotype may help identify those at risk for schizophrenia better. The present study aims to investigate MPAs and gamma oscillatory activity in schizophrenia patients, their unaffected first degree relatives and healthy controls and appreciate whether they can be used together as a composite endophenotype.

METHODS

This was a cross sectional family study conducted at a tertiary care mental health setup. Ninety participants including schizophrenia patients, their first degree relatives and controls (thirty each) were assessed for MPAs on the Extended Waldrop Scale. All participants underwent an awake, resting 192-channel EEG recording. Spectral power and coherence in 30-100Hz gamma bands were estimated using Welch's averaged periodogram method. One-way ANOVA, chi square test were used for comparing socio-demographic-clinical variables. MANOVA supplemented by one-way ANOVAs (post hoc Tukey HSD) were done for comparison of spectral measures. Pearson's correlation, step-by-step linear discriminant functional and intra-familial correlation analysis were subsequently performed.

RESULTS

An endophenotype pattern of finding was found for MPAs in the craniofacial region, the total number of MPAs, spectral power in right temporal region on all bands and in the right parietal region in 50-70Hz and 70-100Hz gamma bands. The three groups were most accurately classified when MPA total score, right temporal 30-50Hz gamma power and right occipital 'intra hemispheric' 50-70Hz gamma coherence were considered together than when considered independently. Significant intra familial correlation was seen for MPA total score and right temporal gamma 30-50Hz power.

CONCLUSION

Composite evaluation of two developmentally linked markers i.e. MPAs and gamma spectral measures may prove useful in categorizing schizophrenia and identifying at-risk individuals.

[Neurological soft signs in early onset schizophrenia]

INTRODUCTION

Neurological soft signs (NSS) are subtle neurological abnormalities that cannot be linked to the achievement of a specific region of the central nervous system and which are not part of a particular neurological syndrome. These signs are observed in the case of diseases supporting the neurodevelopmental model such as schizophrenia in general and its early form defined notably by an age of onset of less than 18 years. Indeed, the NSS belong to a set of clinical, cognitive, electrophysiological and neuroanatomical markers reflecting neurodevelopmental brain abnormalities in patients with schizophrenia.

OBJECTIVE

The objectives of our study were to determine the prevalence, the scores, and the nature of neurological soft signs (NSS) in adolescent patients suffering from early onset schizophrenia diagnosis in comparison to healthy controls, and to explore the correlations between NSS and the demographic, clinical and therapeutic features of these patients.

MATERIALS AND METHODS

Twelve adolescents were recruited in the Child Psychiatry Department at the Razi Hospital (Tunisia), with the diagnosis of schizophrenia according to the DSM-IV supplemented by the Kiddie SAD PL. They were matched by age and educational level with twelve healthy controls without psychiatric family or personal history. The clinical status of the patients was assessed using the Positive and Negative Syndrome Scale (PANSS). Neurological soft signs (NSS) were rated with the Neurological Soft Signs Examination (NSSE) by Krebs et al. (2000) for the two groups. This scale is composed of 23 items exploring motor coordination, motor integrative function, sensory integration, involuntary movements and quality of lateralization.

RESULTS

The mean age of our population was 14.7 years. The average age of onset of the disease was 12.2 years. The sex-ratio was 1.4. Educational level was 7.4 years. The PANSS mean total score was 74.3. The mean daily dose, in chlorpromazine equivalents, was 523.9 mg/day. Four patients received a strict monotherapy of antipsychotics, while the other patients were receiving an association of two neuroleptics. The prevalence of NSS was 100% (cut-off point=11) with a mean total score of 29.3±4.1. The highest score was for the motor coordination (10.1). As for the control group, the mean total score was 7±1.3. A highly significant difference was found between patients and controls for all sub-scores of NSS. Negative correlations were found in patients, between age and neurological soft signs total score (P=0.05; r=-0.57) and also with sensory integration score (P=0.04; r=-0.58). The NSS total score was also correlated with low educational level (P=0.03; r=-0.61). There was no correlation between neurological soft signs scores and PANSS scores or the daily dose of antipsychotics.

CONCLUSION

The prevalence and NSS scores are high among young people with early onset schizophrenia diagnosis illustrating the existence of structural abnormalities of the brain, themselves consequences of early neurodevelopmental disturbances, which would support the neurodevelopmental hypothesis concerning this pathology.

Dopaminergic basis of the psychosis-prone personality investigated with functional magnetic resonance imaging of procedural learning

Previous evidence shows a reliable association between psychosis-prone (especially schizotypal) personality traits and performance on dopamine (DA)-sensitive tasks (e.g., prepulse inhibition and antisaccade). Here, we used blood oxygen level-dependent (BOLD) fMRI and an established procedural learning (PL) task to examine the dopaminergic basis of two aspects of psychosis-proneness (specific schizotypy and general psychoticism). Thirty healthy participants (final N = 26) underwent fMRI during a blocked, periodic sequence-learning task which, in previous studies, has been shown to reveal impaired performance in schizophrenia patients given drugs blocking the DA D2 receptor subtype (DRD2), and to correspond with manipulation of DA activity and elicit fronto-striatal-cerebellar activity in healthy people. Psychosis-proneness was indexed by the Psychoticism (P) scale of the Eysenck Personality Questionnaire-Revised (EPQ-R; 1991) and the Schizotypal Personality Scale (STA; 1984). EPQ-R Extraversion and Neuroticism scores were also examined to establish discriminant validity. We found a positive correlation between the two psychosis-proneness measures (r = 0.43), and a robust and unique positive association between EPQ-R P and BOLD signal in the putamen, caudate, thalamus, insula, and frontal regions. STA schizotypy score correlated positively with activity in the right middle temporal gyrus. As DA is a key transmitter in the basal ganglia, and the thalamus contains the highest levels of DRD2 receptors of all extrastriatal regions, our results support a dopaminergic basis of psychosis-proneness as measured by the EPQ-R Psychoticism.

Neural processing of criticism and positive comments from relatives in individuals with schizotypal personality traits

OBJECTIVES. High negative expressed emotion by family members towards schizophrenia patients increases the risk of subsequent relapse. The study aimed to determine whether individuals with high schizotypy (HS) and low schizotypy (LS) would differ in activation of brain areas involved in cognitive control when listening to relative criticism. METHODS. Twelve HS and 12 LS individuals listened to relative's critical, positive and neutral comments about them while undergoing functional MRI. Activation maps in the two groups during the comments were compared using SPM5. RESULTS. The left superior frontal and middle frontal gyri and bilateral posterior cingulate cortex were activated during criticism, compared to neutral comments, across all participants. While there were no group differences in brain activity for criticism versus neutral comments, the HS group, who had lower current mood relative to the LS group, activated to a lesser extent the thalamus, insula, putamen and brain stem during positive, compared to neutral, comments. CONCLUSIONS. Listening to relative criticism in healthy individuals engages brain areas for cognitive control of negative emotion and self-referential processing. However, HS individuals may have an attenuated ability to respond to rewarding aspects of positive comments due to their lower current mood.

Dynamics of neurological soft signs and its relationship to clinical course in patients with first-episode schizophrenia

The aim of the study was to assess the dynamics of neurological soft signs (NSS) over four years from the clinical onset of schizophrenia, depending on the clinical course of the disease, and to evaluate the relationship of NSS to symptomatic dimensions in patients with first-episode schizophrenia. Sixty-eight patients with first-episode schizophrenia were included in the trial. The clinical status was assessed using Positive and Negative Syndrome Scale (PANSS) at the same time as the neurological examination, at admission to the hospital for first-episode schizophrenia and at a check-up examination four years later. The assessment of NSS using the Neurological Evaluation Scale (NES) coincided with the assessment of the clinical condition of the patients. According to the Andreasen remission criterion of schizophrenia, after four years we found that 57% of patients' were remitters and 43% were non-remitters. During the monitoring period, in remitters total NES score and sensory integration/sequencing of motor acts items of the NES decreased. In non-remitters, increase in the total NES score and the 'others' item of the NES was observed. A connection between the dynamics of NSS and the clinical course of schizophrenia, over the period of four years, and a relationship between NSS and negative schizophrenia symptoms was found.

Neurological soft signs and psychometrically identified schizotypy in a sample of young conscripts

There is growing interest in the connection between neurological soft signs (NSS) and schizophrenia spectrum disorders such as schizotypal personality disorder. The association between NSS and schizotypy was investigated in a subgroup of 169 young healthy male military conscripts included in the Athens Study of Psychosis Proneness and Incidence of Schizophrenia. During their first 2 weeks in the National Basic Air Force Training Centre (T(1)-first assessment), subjects completed the Schizotypal Personality Questionnaire (SPQ), the Symptom Checklist-90-Revised (SCL-90-R), and the Raven's Progressive Matrices (RPM). Then, 2 years later (T(2)-second assessment), at the time of military discharge, they were tested for NSS with the Neurological Evaluation Scale (NES) and reevaluated with the SPQ, the SCL-90-R and additionally the Structured Clinical Interview for Personality Disorders (SCID-II) for the Diagnostic and Statistical Manual of Mental Disorders Third Edition, Revised (DSM-III-R). NSS were more prominent in conscripts with high schizotypy; scores on Sequencing of Complex Motor Acts (SCMA) and the "Other Soft Signs" (OSS) subscales were correlated with high schizotypy at both T(1) and T(2). Increased levels of SCMA as well as the total NSS score were correlated at both T(1) and T(2) with the interpersonal SPQ factor (reflecting negative schizotypy). The findings support the proposal that negative schizotypy might be associated with subtle neurodevelopmental abnormalities.

Cerebellar-dependent eyeblink conditioning deficits in schizophrenia spectrum disorders

Accumulating evidence suggests that abnormalities in neural circuitry and timing associated with the cerebellum may play a role in the pathophysiology of schizophrenia. Schizotypal personality disorder (SPD) may be genetically linked to schizophrenia, but individuals with SPD are freer from potential research confounds and may therefore offer insight into psychophysiological correlates of schizophrenia. The present study employed a delay eyeblink conditioning (EBC) procedure to examine cerebellar-dependent learning in schizophrenia, SPD, and healthy control subjects (n = 18 per group) who were matched for age and gender. The conditioned stimulus was a 400-ms tone that coterminated with a 50 ms unconditioned stimulus air puff. Cognitive performance on the Picture Completion, Digit Symbol Coding, Similarities, and Digit Span subscales of the Wechsler Adult Intelligence Scale--Third Edition was also investigated. The schizophrenia and SPD groups demonstrated robust EBC impairment relative to the control subjects; they had significantly fewer conditioned responses (CRs), as well as smaller CR amplitudes. Schizophrenia subjects showed cognitive impairment across subscales compared with SPD and control subjects; SPD subjects showed intermediate performance to schizophrenia and control subjects and performed significantly worse than controls on Picture Completion. Impaired EBC was significantly related to decreased processing speed in schizophrenia spectrum subjects. These findings support the role of altered cortico-cerebellar-thalamic-cortical circuitry in the pathophysiology of schizophrenia spectrum disorders.

A systematic review and meta-analysis of neurological soft signs in relatives of people with schizophrenia

BACKGROUND

Neurological soft signs are subtle but observable impairments in motor and sensory functions that are not localized to a specific area of the brain. Neurological soft signs are common in schizophrenia. It has been established that soft signs meet two of five criteria for an endophenotype, namely: association with the illness, and state independence. This review investigated whether soft signs met a further criterion for an endophenotype, namely familial association. It was hypothesized that if familial association were present then neurological soft signs would be: (a) more common in first-degree relatives of people with schizophrenia than in controls; and (b) more common in people with schizophrenia than in their first-degree relatives.

METHOD

A systematic search identified potentially eligible studies in the EMBASE (1980-2011), OVID - MEDLINE (1950-2011) and PsycINFO (1806-2011) databases. Studies were included if they carried out a three-way comparison of levels of soft signs between people with schizophrenia, their first-degree relatives, and normal controls. Data were extracted independently by two reviewers and cross-checked by double entry.

RESULTS

After screening 8678 abstracts, seven studies with 1553 participants were identified. Neurological soft signs were significantly more common in first-degree relatives of people with schizophrenia than in controls (pooled standardised mean difference (SMD) 1.24, 95% confidence interval (c.i) 0.59-1.89). Neurological soft signs were also significantly more common in people with schizophrenia than in their first-degree relatives (SMD 0.92, 95% c.i 0.64-1.20). Sensitivity analyses examining the effects of age and group blinding did not significantly alter the main findings.

CONCLUSIONS

Both hypotheses were confirmed, suggesting that the distribution of neurological soft signs in people with schizophrenia and their first-degree relatives is consistent with the endophenotype criterion of familial association.

Neural processing of social rejection: the role of schizotypal personality traits

A fear of being rejected can cause perceptions of more insecurity and stress in close relationships. Healthy individuals activate the dorsal anterior cingulate cortex (dACC) when experiencing social rejection, while those who are vulnerable to depression deactivate the dACC presumably to downregulate salience of rejection cues and minimize distress. Schizotypal individuals, characterized by unusual perceptual experiences and/or odd beliefs, are more rejection sensitive than normal. We tested the hypothesis, for the first time, that individuals with high schizotypy also have an altered dACC response to rejection stimuli. Twenty-six healthy individuals, 14 with low schizotypy (LS) and 12 with high schizotypy (HS), viewed depictions of rejection and acceptance and neutral scenes while undergoing functional MRI. Activation maps in LS and HS groups during each image type were compared using SPM5, and their relation to participant mood and subjective ratings of the images was examined. During rejection relative to neutral scenes, LS activated and HS deactivated the bilateral dACC, right superior frontal gyrus, and left ventral prefrontal cortex. Across both groups, a temporo-occipito-parieto-cerebellar network was active during rejection, and a left fronto-parietal network during acceptance, relative to neutral scenes, and the bilateral lingual gyrus during rejection relative to acceptance scenes. Our finding of dACC-dorso-ventral PFC activation in LS, but deactivation in HS individuals when perceiving social rejection scenes suggests that HS individuals attach less salience to and distance themselves from such stimuli. This may enable them to cope with their higher-than-normal sensitivity to rejection.

Neurological soft signs in individuals with schizotypal personality features

OBJECTIVE

The current study attempted to examine the prevalence of neurological soft signs and their relationships with schizotypal traits in individuals with psychometrically defined schizotypal personality disorder (SPD) features.

METHOD

Sixty-four individuals with SPD-proneness and 51 without SPD-proneness were recruited for the present study. The soft signs subscales of the Cambridge Neurological Inventory were administered to all participants; the Schizotypal Personality Questionnaire (SPQ) was administered to SPD-proneness and non-SPD-proneness participants.

RESULTS

The SPD-proneness participants demonstrated significantly higher prevalence of soft signs than those without SPD-proneness. SPQ subscales were significantly associated with ratings of motor coordination, sensory integration and total soft signs.

CONCLUSION

These findings suggest that neurological soft signs are trait markers of schizophrenia.

Dermatoglyphic indices and minor physical anomalies in patients with schizophrenia and related disorders, their first-degree biological relatives, and non psychiatric controls

Abnormalities in dermatoglyphic indices and minor physical anomalies (MPAs) are two permanent markers of fetal development that have been studied in schizophrenia. This study sought to: (1) compare select dermatoglyphic indices across patients, first-degree relatives, and non psychiatric controls; (2) assess for associations between dermatoglyphic indices and symptoms in patients and schizotypal features in relatives and controls; and (3) examine correlations between dermatoglyphics and MPAs. The two types of markers were assessed in 62 patients with schizophrenia and related disorders, 36 of their unaffected first-degree relatives, and 47 non psychiatric controls. Symptoms were measured in patients and schizotypy was assessed in relatives and controls. Analyses took into account potential demographic confounders and non independence between patients and relatives. No significant differences in dermatoglyphic indices (total finger ridge count; ridge count asymmetry; numbers of arches, loops, and whorls) were found across the three groups. Patients' and their own relatives' dermatoglyphic indices were moderately to strongly correlated (rho=0.33-0.66). Dermatoglyphic indices were unrelated to patients' cross-sectional symptom severity and were generally unrelated to relatives' and controls' levels of schizotypy. Several correlations among dermatoglyphic indices and MPAs were found in this exploratory analysis, particularly among relatives and controls. Implications for future research are discussed.

Developmental instability in social anhedonia: an examination of minor physical anomalies and clinical characteristics

Developmental instability (DI) refers to the inability of the developing brain to buffer the effects of genetic and environmental insults. This concept has been invoked to better understand how fetal brain development goes awry in schizophrenia and related spectrum disorders. This study examined one marker of DI, minor physical anomalies (MPAs), and its association with a putative indicator of schizotypy, the trait of social anhedonia. MPAs and clinical symptoms were assessed within a community sample of psychometrically identified individuals high in social anhedonia and a matched group of healthy controls. Results indicated that, compared to the controls, MPAs were elevated in the social anhedonia group. Additionally, within the social anhedonia group, MPAs were significantly correlated with clinical ratings of schizoid personality disorder characteristics and also showed strong associations with schizotypal personality disorder ratings. These findings indicate a relationship between developmental anomalies and negative schizotypy and suggest that, when combined with psychometrically identified risk, the presence of MPAs may further elevate the probability of clinical manifestations of schizophrenia-spectrum characteristics.

Neurological soft signs and schizotypal dimensions in unaffected siblings of patients with schizophrenia

The objectives were to determine the neurological soft signs (NSS) scores in unaffected siblings of patients with schizophrenia compared with healthy controls and to examine their relationships with schizotypal dimensions. Participants comprised 31 unaffected siblings of patients with schizophrenia and 60 healthy controls matched according to age, gender and school level who were assessed by the Schizotypal Personality Questionnaire (SPQ) and the Krebs et al. NSS Scale. Higher NSS total scores and sub-scores were found in the unaffected siblings compared with the controls. The SPQ total score was significantly higher in unaffected siblings compared with control subjects. The NSS total score was positively correlated with the SPQ total score and the SPQ disorganization sub-score in unaffected siblings of patients with schizophrenia. Additionally, in unaffected siblings, motor coordination and integration abnormalities were positively correlated with the SPQ total score and the cognitive-perceptual sub-score. Motor integration abnormalities were also correlated with the SPQ disorganization sub-score. These results reveal that NSS, especially motor signs, are associated with some schizotypal dimensions in siblings of patients with schizophrenia, suggesting the value of using both assessments to study high risk populations.

Neurological soft signs in psychometrically identified schizotypy

Patients with schizophrenia often exhibit structural brain abnormalities, as well as neurological soft signs (NSS), consistent with its conceptualization as a neurodevelopmental disorder. NSS are mild, presumably nonlocalizing, neurological impairments that are inferred from performance deficits in domains such as sensory integration, motor coordination, and motor sequencing. The vulnerability for schizophrenia is presumed to be expressed across a broad continuum of impairment referred to as schizotypy. It is hypothesized that nondisordered people along the schizotypy continuum should exhibit elevated rates of NSS. The present study examined the relation of psychometrically identified positive and negative schizotypy with NSS using the Neurological Evaluation Scale in a nonclinically ascertained sample of young adults (n=177). As hypothesized, negative, but not positive, schizotypy was related to increased NSS in tasks that assessed fine and gross motor coordination, motor sequencing, eye movement abnormalities, and memory recall. However, positive schizotypy was associated with increased NSS in tasks related to sensory integration dysfunction. In general, the positivexnegative schizotypy interaction term was unrelated to individual NSS tasks. The findings support: a) the theory that the vulnerability for schizophrenia is expressed across a broad continuum of subclinical and clinical impairment referred to as schizotypy; b) the multidimensional structure of schizotypy; and c) the notion that schizotypy is an appropriate construct for understanding the etiology and development of schizophrenia-spectrum disorders.

Neurological soft signs in non-psychotic first-degree relatives of patients with schizophrenia: a systematic review and meta-analysis

BACKGROUND

Neurological soft signs (NSS) have been associated with the neuropsychopathology of schizophrenia, and have been proposed as candidate endophenotypes for this clinical group. However, the prevalence rate of NSS in non-psychotic first-degree relatives is not fully known. The authors systematically and quantitatively reviewed the literature to determine the magnitude of difference between: (1) first-degree non-psychotic relatives of schizophrenia patients and healthy controls, and (2) between schizophrenia patients and their non-psychotic relatives.

METHODS

An article search and meta-analysis was conducted using the Comprehensive Meta-Analysis software package to quantify group differences. Mean effect sizes (standardized group mean differences) and associated confidence intervals along with homogeneity and publication bias tests and statistics were calculated.

RESULTS

Search procedures identified 11 independent studies that met the inclusion criteria. Quantification of NSS differences yielded a mean effect size of 0.81 for schizophrenia patients and their non-psychotic relatives and 0.97 for non-psychotic relatives of schizophrenia patients and healthy controls.

CONCLUSIONS

The current findings show that there are large group differences in NSS prevalence between patients with schizophrenia, non-psychotic relatives, and healthy controls. These results are consistent with the argument that NSS are familial in nature, segregate with the illness and may be valid and useful endophenotypes.

Neurodevelopmental factors associated with schizotypal symptoms among adolescents at risk for schizophrenia

Schizophrenia has come to be viewed as a neurodevelopmental disorder that is characterized by genetic vulnerability, stressors during the prenatal period that may be marked by minor physical anomalies and neurobehavioral deficits that emerge in early development. Less is known about the neurodevelopmental origins of schizotypal personality symptoms. The present study examines schizotypal symptoms in Israeli adolescents (mean age = 16.79 years) who have not yet reached the developmental period during which first schizophrenic episode is most likely to emerge: 39 adolescent offspring of parents with schizophrenia, 39 offspring of parents with other psychiatric disorders, and 36 offspring of parents with no history of mental illness. The Semi-Structured Kiddie Interview for Personality Syndromes was used to assess cognitive–perceptual, interpersonal, and disorganized schizotypal symptoms. Interpersonal schizotypal symptoms were more prevalent in the schizophrenia offspring group than in the no-mental-illness offspring group. Among the schizophrenia offspring group, interpersonal, but not cognitive–perceptual, schizotypal symptoms were associated with minor physical anomalies, fine motor dyscoordination, and deficits in executive functioning during adolescence. Among young people whose parents did not have schizophrenia, cognitive–perceptual schizotypal symptoms were correlated with deficits in executive functioning. Adolescent schizotypal symptoms were associated with neurobehavioral symptoms measured during middle childhood in a subgroup of the sample that had been assessed prospectively. Finally, young people who had genetic risk for schizophrenia, minor physical anomalies, and neurobehavioral signs together were at markedly increased risk for symptoms of interpersonal schizotypal symptoms, compared to young people with one or none of these risk factors.

Associations between past alcohol, cannabis, and cocaine use and current schizotypy among first-degree relatives of patients with schizophrenia and non-psychiatric controls

Associations between past use of alcohol, cannabis, and cocaine and various domains of schizotypy were examined in first-degree relatives of patients with schizophrenia and non-psychiatric controls. Substance use was operationalized in three ways: (1) having ever used the substance, (2) age at first use, and (3) past frequency/amount of use during three time periods in late adolescence/early adulthood. Schizotypy was assessed using the Schizotypal Personality Questionnaire (SPQ). Participants who had ever used cannabis had significantly higher cognitive-perceptual, interpersonal, and total schizotypy scores compared to those who had not. Younger age of alcohol use onset was associated with more schizotypy in adulthood, and younger age of first cannabis use was related to more interpersonal schizotypy. More frequent/heavier use of alcohol in the 25-29 age-range, and cannabis in early adulthood, were associated with more schizotypy. The use of addictive substances, particularly cannabis, is related to schizotypy in complex ways.

Potential Endophenotype for Schizophrenia: Neurological Soft Signs

Introduction: Neurological soft signs (NSS) are suggested as a candidate endophenotype for schizophrenia. This article aims to review relevant literature and discuss the role of NSS in understanding schizophrenia. Methods: This is an update on a review article published in 2003. Articles from 2003 onwards were specifically reviewed and discussed with relevance to the role of NSS as endophenotype for schizophrenia. Results: Consistent data suggest an excess of NSS in schizophrenic patients. NSS appear to be related to schizophrenic symptoms, in particular negative symptoms and disorganisation. Information on NSS and demographic correlates is scarce, and the confounding effects between age, education and intelligence on NSS constitute an important gap in current knowledge. Longitudinal data suggest NSS as both a trait and state variable in the course of disease. NSS are not specific with regard to diagnosis, although there are claims that individual sub-components may be more specific. The weight of evidence raises question on the specificity of NSS for schizophrenia. Conclusions: The usefulness and feasibility of NSS as a specific endophenotype target for schizophrenia is unclear. However, NSS remain an important feature and symptom correlate of schizophrenia. Future research should focus on delineating the effects of NSS from those of confounding demographic variables, and the stability of NSS over the course of illness to elucidate its role in schizophrenia. Key words: Diagnostic specificity, Neurological examination abnormalities, Psychotic symptoms, Review, Trait

The relationship between interview-based schizotypal personality dimension scores and the continuous performance test

The existing research that has examined cognitive performance in samples with subclinical schizotypal personality features has been largely limited to psychometric self-report questionnaires, which may be biased by distorted self-awareness of symptoms. The present study examined the relationship between performance on a degraded-AX continuous performance test (CPT) and continuous dimension scores created from a structured clinical interview for schizotypal personality disorder (SPD), which reflected both the breadth and severity of schizotypal personality symptoms, in 52 undergraduate students. Only one participant met full diagnostic criteria for SPD. The overall dimension score from the SPD clinical interview showed a positive correlation with both omission (r(s)=.47) and false alarm (r(s)=.41) errors on the CPT. Interpersonal symptoms were positively correlated with omission errors (r(s)=.47), while Disorganized symptoms were positively correlated with false alarm errors (r(s)=.40). Results suggest that higher SPD interview-based dimension scores are associated with lower levels of performance on the CPT, even when examining a relatively subclinical sample of young adults. In contrast, scores from the psychometric Abbreviated Schizotypal Personality Questionnaire in the same sample did not correlate with accuracy measures on the CPT, suggesting that the interview-based measure of schizotypal personality may have a stronger relationship with CPT accuracy. Findings also add to a growing literature suggesting that Interpersonal SPD symptoms are primarily related to omission errors, while Disorganized SPD symptoms are primarily related to false alarm errors.

Physical manifestations of neurodevelopmental disruption: are minor physical anomalies part of the syndrome of schizophrenia?

The well-documented excess of minor physical anomalies (MPAs) among individuals with schizophrenia generally supports the neurodevelopmental model, which posits that both genetic and environmental factors contribute to structural and functional brain changes in the intrauterine and perinatal periods that predispose one to developing schizophrenia. This review synthesizes select areas of research findings on MPAs to address the question, Are MPAs part of the syndrome of schizophrenia? Although MPAs are not specific to schizophrenia, their presence in some patients indicates that aberrations in the development of the nervous system contribute to risk for the disorder. The broadly defined, heterogeneous MPA construct may be of limited value in further elucidating the specific pathophysiology of schizophrenia, though particular anomalies, such as those pertaining to nasal volumes, palatal abnormalities, or craniofacial morphology, may be informative. Given the availability of more sophisticated microarray technologies, and in light of recent findings on spontaneous mutations in patients with schizophrenia, it is possible that MPAs will prove to be useful in identifying etiologic subtypes and/or the loci of genetic risk factors. It remains to be determined whether MPAs-which, of course, are fixed markers present throughout childhood and adolescence well before the onset of the prodrome and psychosis-may have utility in terms of risk stratification for future preventive efforts. Taken together, research findings on MPAs indicate that these minor anomalies are indeed part of some schizophrenia syndromes, representing a stable systemic or physical set of manifestations of the underlying neurodevelopmental processes that lead to the illness.

No association between psychometrically-determined schizotypy and olfactory identification ability in first-degree relatives of patients with schizophrenia and non-psychiatric controls

OBJECTIVE

This study examined potential associations between schizotypy--including positive, negative, and disorganized domains--and olfactory identification ability. Based on a prior report (Park, S., Schoppe, S., 1997. Olfactory identification deficit in relation to schizotypy. Schizophr. Res. 26, 191-197), it was hypothesized that positive and negative schizotypy would be associated with poorer olfactory identification ability, at least among male participants.

METHOD

As part of a larger study, the Schizotypal Personality Questionnaire (SPQ) and University of Pennsylvania Smell Identification Test (UPSIT) were administered to 98 participants, including 44 healthy first-degree relatives of individuals with schizophrenia and related disorders and 54 non-psychiatric controls. Potential associations between SPQ subscales and UPSIT score were examined while considering the effects of sociodemographic variables on these measures.

RESULTS

SPQ and UPSIT scores were not significantly different in first-degree relatives and controls. There was no evidence of an association between SPQ domains and UPSIT score, even when controlling for possible confounding variables, including age and educational attainment.

CONCLUSIONS

The nascent literature on potential associations between schizotypy and olfactory identification ability has yielded mixed findings to date. The current study does not support a correlation between these two markers, and this lack of association--in addition to equal olfactory identification performance in relatives and controls--casts doubt on the utility of the UPSIT as a measure of an endophenotypic trait. Future research would benefit from larger, more diverse samples; the addition of objective, interviewer-based measures of schizotypy; and attention to potentially confounding sociodemographic variables.

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.

Neurological soft signs and minor physical anomalies in patients with schizophrenia and related disorders, their first-degree biological relatives, and non-psychiatric controls

BACKGROUND

Subtle neurological impairments and inconsequential minor anomalies of the face and limbs are manifestations of neurodevelopmental and ontogenic abnormalities that are consistently found at higher rates in individuals with schizophrenia compared to healthy controls. Limited research has been conducted on these traits among biological relatives of patients with schizophrenia. This study hypothesized that the mean NSS score and the mean MPA score would be greater in patients than controls and that first-degree relatives would have intermediate scores. Furthermore, it was hypothesized that NSS scores and MPA scores would not be correlated. This study also explored correlations between patients' NSS and MPA scores and their relatives' respective scores and sought to replicate the finding that NSS are associated with negative and disorganized symptoms of schizophrenia, whereas MPAs are not.

METHODS

Patients with schizophrenia and related psychotic disorders (n=73), first-degree relatives (n=44), and non-psychiatric controls (n=54) were assessed. Measures included the Neurological Evaluation Scale, a structured examination for MPAs, and the Positive and Negative Syndrome Scale in patients. Analyses accounted for clustering within families.

RESULTS

Both NSS and MPAs were greater in patients than controls, and first-degree relatives had intermediate scores. Furthermore, NSS and MPA scores were independent in all three groups. Correlations were found between patients' and their relatives' scores on one NES subscale (sensory integration) and total MPA score and several MPA regions (eyes, ears, and hands). This study replicated previous findings that in patients with schizophrenia, NSS are associated with negative, disorganized, and other domains of symptoms. Associations between MPAs and symptoms were sparse and inconsistent.

CONCLUSION

These findings suggest that NSS and MPAs represent two quite distinct markers of risk for schizophrenia that may stem from genetic factors, as well as from environmental/developmental influences. Future research on multivariable risk prediction models may benefit from the use of somewhat independent risk markers or endophenotypes.