Abnormal orienting in schizotypal personality disorder

Dysfunctional personality traits in adolescence: effects on alerting, orienting and executive control of attention

The present study examined attentional networks performance in 39 adolescents with dysfunctional personality traits, split into two group, Group < 10 and Group ≥ 10, according to the number of criteria they met at the Structured Clinical Interview for DSM-IV Axis II Personality Disorders. The attentional performance has been tested by means of a modified version of the Attentional Network Test (ANTI-V) which allows testing both phasic and tonic components of the alerting system, the exogenous aspect of the orienting system, the executive network and their interactions. Results showed that the orienting costs of having an invalid spatial cue were reduced in the Group ≥ 10 criteria compared to the Group < 10. Moreover, adolescents included in the Group ≥ 10 showed lower conflict when attention was cued to the target location (valid trials) but showed normal interference when there was no overpowering focus of attention (invalid trials). The results found with ANOVA after splitting the sample into two categorical groups were also observed in a complementary correlation analysis keeping intact the continuous nature of such variables. These findings are consistent with the notion that dysfunctional features of personality disorders may represent the psychological manifestations of a neuropsychological abnormality in attention and executive functioning. Finally, we discuss the implications of this attentional anomaly for dysfunctional personality traits and behaviour.

Uncomfortably numb: new evidence for suppressed emotional reactivity in response to body-threats in those predisposed to sub-clinical dissociative experiences

INTRODUCTION

Depersonalisation and derealisation disorders refer to feelings of detachment and dissociation from one's "self" or surroundings. A reduced sense of self (or "presence") and emotional "numbness" is thought to be mediated by aberrant emotional processing due to biases in self-referent multi-sensory integration. This emotional "numbing" is often accompanied by suppressed autonomic arousal to emotionally salient stimuli.

METHODS

118 participants completed the Cambridge Depersonalisation scale [Sierra, & Berrios, 2000. The Cambridge Depersonalisation Scale: A new instrument for the measurement of depersonalisation. Psychiatry Research, 93, 153-164)] as an index of dissociative anomalous experience. Participants took part in a novel "Implied Body-Threat Illusion" task; a pantomimed injection procedure conducted directly onto their real body (hand). Objective psychophysiological data were recorded via standardised threat-related skin conductance responses and finger temperature measures.

RESULTS

Individuals predisposed to depersonalisation/derealisation revealed suppressed skin conductance responses towards the pantomimed body-threat. Although the task revealed a reliable reduction in finger temperature as a fear response, this reduction was not reliably associated with measures of dissociative experience.

CONCLUSIONS

The present findings significantly extend previous research by revealing emotional suppression via a more direct body-threat task, even for sub-clinical groups. The findings are discussed within probabilistic and predictive coding frameworks of multi-sensory integration underlying a coherent sense of self.

Increased distractibility in schizotypy: Independent of individual differences in working memory capacity?

Individuals with schizophrenia typically show increased levels of distractibility. This has been attributed to impaired working memory capacity (WMC), since lower WMC is typically associated with higher distractibility, and schizophrenia is typically associated with impoverished WMC. Here, participants performed verbal and spatial serial recall tasks that were accompanied by to-be-ignored speech tokens. For the few trials wherein one speech token was replaced with a different token, impairment was produced to task scores (a deviation effect). Participants subsequently completed a schizotypy questionnaire and a WMC measure. Higher schizotypy scores were associated with lower WMC (as measured with operation span, OSPAN), but WMC and schizotypy scores explained unique variance in relation to the mean magnitude of the deviation effect. These results suggest that schizotypy is associated with heightened domain-general distractibility, but that this is independent of its relationship with WMC.

Neuropsychological effects associated with recreational cocaine use

RATIONALE

Recent evidence suggests that recreational cocaine use is on the increase, with the UK reporting one of the highest levels of use in the EU (EMCDDA 2010). Nevertheless, very few studies have addressed the neuropsychological effects associated with non-dependent recreational cocaine use.

OBJECTIVES

The current study aimed to assess whether recreational cocaine users show neuropsychological deficits on a battery of tests, previously shown to be sensitive to cocaine-dependent and psychosis-prone individuals. Schizotypal traits were also measured.

METHODS

Recreational cocaine users (n = 17) were compared with controls (n = 24) on drug use patterns, the General Health Questionnaire, the Brief Schizotypal Personality Questionnaire (SPQ-B) and four neuropsychological tasks: spatial working memory, intra/extra-dimensional set shifting, the Stocking of Cambridge and the rapid visual processing.

RESULTS

Relative to controls, recreational cocaine users produced significantly more errors on the intra/extra-dimensional set shift task and completed fewer stages, made significantly more six box stage errors on the spatial working memory task, and made significantly more errors and fewer hits, with overall poorer detection rates on the rapid visual processing task. Recreational cocaine users reported significantly higher scores on the cognitive perceptual and disorganised thinking SPQ-B subscales and total SPQ-B scores compared to controls.

CONCLUSIONS

Recreational cocaine users displayed impairments on tasks tapping sustained attention, attentional shifting and spatial memory and reported higher schizotypal trait expression. These findings are consistent with the emerging literature suggesting subtle cognitive deficits, putatively reflecting underlying dopaminergic dysfunction, in non-dependent, recreational cocaine users.

A developmental increase in allostatic load from ages 3 to 11 years is associated with increased schizotypal personality at age 23 years

Although allostatic load has been investigated in mood and anxiety disorders, no prior study has investigated developmental change in allostatic load as a precursor to schizotypal personality. This study employed a multilevel developmental framework to examine whether the development of increased allostatic load, as indicated by impaired sympathetic nervous system habituation from ages 3 to 11 years, predisposes to schizotypal personality at age 23 years. Electrodermal activity to six aversive tones was recorded in 995 subjects at age 3 years and again at 11 years. Habituation slopes at both ages were used to create groups who showed a developmental increase in habituation (decreased allostatic load), and those who showed a developmental decrease in habituation (increased allostatic load). Children who showed a developmental increase in allostatic load from ages 3 to 11 years had higher levels of schizotypal personality at 23 years. A breakdown of total schizotypy scores demonstrated specificity of findings to cognitive-perceptual features of schizotypy. Findings are the first to document a developmental abnormality in allostasis in relation to adult schizotypal personality. The relative failure to develop normal habituation to repeated stressors throughout childhood is hypothesized to result in an accumulation of allostatic load and consequently increased positive symptom schizotypy in adulthood.

The relationship among neuregulin 1-stimulated phosphorylation of AKT, psychosis proneness, and habituation of arousal in nonclinical individuals

BACKGROUND

Previous studies reported an association between weak habituation of skin conductance orienting response and psychosis proneness. The aim of this study was to investigate the relationship among neuregulin 1 (NRG1)-stimulated AKT phosphorylation (a putative marker of psychosis), orienting response habituation, delusional ideas, anxiety, and depression in nonclinical individuals.

METHODS

One hundred twenty individuals participated in the skin conductance measurements. Weak and strong habituators were compared on measures of NRG1-stimulated AKT phosphorylation in B lymphoblasts, delusional ideas, anxiety, and depression. The predictors of delusional ideas were determined by multiple regression analysis.

RESULTS

Weak habituators displayed higher levels of delusional ideas/anxiety and a lower ratio of phosphorylated AKT as compared with strong habituators. There were 3 significant predictors of delusional ideas: decreased habituation, NRG1-induced AKT phosphorylation, and anxiety. Age, gender, education, IQ, and depression did not predict delusional ideas.

CONCLUSIONS

These results suggest that decreased habituation of arousal, NRG1-induced AKT phosphorylation, and anxiety are related to delusional ideation in the general population.

Salivary alpha-amylase as a longitudinal predictor of children's externalizing symptoms: respiratory sinus arrhythmia as a moderator of effects

Salivary alpha-amylase (sAA) was examined as a predictor of children's externalizing symptoms cross-sectionally when children were in the 3rd grade (T1; N=64) and again in the 5th grade (T2; N=54) and longitudinally over two years. Parasympathetic nervous system (PNS) activity, indexed by respiratory sinus arrhythmia (RSA), was examined as a moderator of the sAA and child externalizing link. Participants were healthy, typically developing children, 34% of whom were African American and the rest European American. At each time point, saliva samples were collected during afternoon laboratory visits and assayed for sAA. Children's RSA was measured during baseline conditions and in response to an inter-adult argument and a star-tracing task. Cross-sectional associations between sAA and externalizing symptoms at T1 and T2 were moderated by PNS functioning. Longitudinally, sAA was directly associated with changes in externalizing symptoms in a non-linear fashion. Specifically, lower externalizing symptoms were predicted for children with moderate levels of sAA, but higher externalizing was predicted for children with higher or lower levels of sAA. Findings highlight the importance of the contemporaneous assessment of SNS and PNS functioning in the prediction of child psychopathology, and the need to examine curvilinear relations between ANS functioning and behavior.

Combining gene expression, demographic and clinical data in modeling disease: a case study of bipolar disorder and schizophrenia

Background

This paper presents a retrospective statistical study on the newly-released data set by the Stanley Neuropathology Consortium on gene expression in bipolar disorder and schizophrenia. This data set contains gene expression data as well as limited demographic and clinical data for each subject. Previous studies using statistical classification or machine learning algorithms have focused on gene expression data only. The present paper investigates if such techniques can benefit from including demographic and clinical data.

Results

We compare six classification algorithms: support vector machines (SVMs), nearest shrunken centroids, decision trees, ensemble of voters, naïve Bayes, and nearest neighbor. SVMs outperform the other algorithms. Using expression data only, they yield an area under the ROC curve of 0.92 for bipolar disorder versus control, and 0.91 for schizophrenia versus control. By including demographic and clinical data, classification performance improves to 0.97 and 0.94 respectively.

Conclusion

This paper demonstrates that SVMs can distinguish bipolar disorder and schizophrenia from normal control at a very high rate. Moreover, it shows that classification performance improves by including demographic and clinical data. We also found that some variables in this data set, such as alcohol and drug use, are strongly associated to the diseases. These variables may affect gene expression and make it more difficult to identify genes that are directly associated to the diseases. Stratification can correct for such variables, but we show that this reduces the power of the statistical methods.

Self-face recognition and theory of mind in patients with schizophrenia and first-degree relatives

OBJECTIVE

The hypothesized relationship between theory of mind (ToM) and self-face recognition as well as its potential genetic associations has not been previously explored in patients with schizophrenia and in first-degree relatives with schizotypal personality traits.

METHOD

Ten patients diagnosed with schizophrenia, 10 of their first-degree relatives and 10 healthy controls were included. To assess self-face recognition (SFR), participants were presented images of faces of themselves and others and asked to make rapid 'unfamiliar', 'familiar' and 'self' judgments. As a measure of ToM, subjects were administered the Revised Mind in the Eyes Test (MET [Baron-Cohen, S., Wheelwright, S., Hill, J., Raste, Y., and Plumb, I., 2001. The "Reading the Mind in the Eyes" Test revised version: a study with normal adults, and adults with Asperger syndrome or high-functioning autism. J Child Psychol Psychiatry 42(2), 241-251.]). Schizotypal characteristics in relatives and controls were assessed using a modified version of the Schizotypal Personality Questionnaire (SPQ [Raine, A., 1991. The SPQ: a scale for the assessment of schizotypal personality based on DSM-III-R criteria. Schizophrenia Bulletin 17(4), 555-564.]).

RESULTS

Patients took longer and were less accurate on the SFR task than their relatives who in turn performed worse than healthy controls. Specific ToM deficits in schizophrenia were replicated. There was a relationship between accuracy rates on the MET and SFR tasks. High levels of schizotypal traits such as social anxiety, constricted affect and no close friends were important for both tasks.

CONCLUSIONS

Face recognition deficits and ToM deficits in schizophrenia are apparent. The critical influence of high levels of select schizotypal traits is also highlighted. A deficit in relatives of schizophrenia patients raises the possibility that ToM and face recognition deficits may be candidate endophenotypes for schizophrenia. Support for the hypothesized link between ToM and face recognition is provided.

Cannabis-induced psychosis-like experiences are associated with high schizotypy

OBJECTIVE

Recent studies have suggested that cannabis use is a risk factor for developing schizophrenia. We tested the hypothesis that cannabis use increases the likelihood of psychosis-like experiences in non-clinical participants who scored highly on a measure of schizotypy.

METHOD

The psychological effects of cannabis were assessed in 137 healthy individuals (76% female, mean age 22 years) using a newly developed questionnaire concerned with subjective experiences of the drug: the Cannabis Experiences Questionnaire. The questionnaire has three subscales: Pleasurable Experiences, Psychosis-Like Experiences and After-Effects. Respondents also completed the brief Schizotypal Personality Questionnaire.

RESULTS

Cannabis use was reported by 72% of the sample. Use per se was not significantly related to schizotypy. However, high scoring schizotypes were more likely to report both psychosis-like experiences and unpleasant after-effects associated with cannabis use. The pleasurable effects of cannabis use were not related to schizotypy score.

CONCLUSION

High scoring schizotypes who use cannabis are more likely to experience psychosis-like phenomena at the time of use, and unpleasant after-effects. Our results are consistent with the hypothesis that cannabis use is a risk factor for full psychosis in this group.

On the trail of a cognitive enhancer for the treatment of schizophrenia

The aim of this critical review is to address that the study of cognition and antipsychotics is not always driven by logic and that research into real pro-cognitive drug treatments must be guided by a better understanding of the biochemical mechanisms underlying cognitive processes and deficits. Many studies have established that typical neuroleptic drugs do not improve cognitive impairment. Atypical antipsychotics improve cognition, but the pattern of improvement differs from drug to drug. Diminished cholinergic activity has been associated with memory impairments. Why atypical drugs improve aspects of cognition might lie in their ability to increase dopamine and acetylcholine in the prefrontal cortex. An optimum amount of dopamine activity in the prefrontal cortex is critical for cognitive functioning. Another mechanism is related to procedural learning, and would explain the quality of the practice during repeated evaluations with atypical antipsychotics due to a more balanced blockage of D2 receptors. Laboratory studies have shown that clozapine, ziprasidone, olanzapine, and risperidone all selectively increase acetylcholine release in the prefrontal cortex, whereas this is not true for haloperidol and thioridazine. A few studies have suggested that cholinomimetics or AChE inhibitors can improve memory functions not only in Alzheimer's disease but also in other pathologies. Some studies support the role of decreased cholinergic activity in the cognitive deficits while others demonstrate that decreased choline acetyltransferase activity is related to deterioration in cognitive performance in schizophrenia. Overall, results suggest the hypothesis that the cholinergic system is involved in the cognitive dysfunctions observed in schizophrenia and that increased cholinergic activity may improve these impairments. Furthermore, a dysfunction of glutamatergic neurotransmission could play a key role in cognitive deficits associated with schizophrenia. Further meta-analysis of various clinical trials in this field is required to account for matters on the grounds of evidence-based medicine.

Reduced Electrodermal Activity in Psychopathy-Prone Adolescents

This study tests the hypothesis that psychopathy-prone adolescents show reduced anticipatory skin conductance responding. Electrodermal activity was recorded while participants anticipated and responded to a 105 dB signaled or unsignaled white-noise burst. Using an extreme groups design, the authors used Child Psychopathy Scale (D. R. Lynam, 1997) scores from a community sample of 335 male adolescents (age 16) to form control (n = 65) and psychopathy-prone (n = 65) groups. Significantly more psychopathy-prone participants were nonresponders in the signaled anticipatory (p = .014), signaled responsivity (p = .037), and unsignaled responsivity (p = .003) conditions compared with controls. Anticipatory hyporesponsivity of psychopathy-prone adolescents similar to the electrodermal hyporesponsivity found in psychopathic adults suggests that this autonomic impairment is present by adolescence and may predispose individuals to adult psychopathy.

Slow habituation of induced gamma and beta oscillations in association with unreality experiences in schizotypy

Highly schizotypal individuals exhibit deficits in attentional processing, in particular dysfunctional habituation. This has led to the suggestion that abnormal habituation may represent a trait marker of psychotic vulnerability. This study examined the difference between high- and low-schizotypal individuals' habituation of nonphase-locked gamma and beta-1 oscillations, with and without attention. Measures of schizotypy were obtained from 40 participants and habituation to different tones was examined over trials of three interval lengths, under conditions of attention and inattention. The data showed that all participants habituated over trials with long intervals when attending to the stimuli. However, those participants who scored high on the unreality subscale exhibited significantly less habituation relative to those with low unreality scores for the short-interval trials. Furthermore, there was no difference in the orienting response to the initial stimuli between these subgroups. These results are discussed in terms of a dysfunctional rehearsal process influencing habituation for those with high-unreality scores.

Decreased latent inhibition is associated with increased creative achievement in high-functioning individuals

Reductions in latent inhibition (LI), the capacity to screen from conscious awareness stimuli previously experienced as irrelevant, have been generally associated with the tendency towards psychosis. However, "failure" to screen out previously irrelevant stimuli might also hypothetically contribute to original thinking, particularly in combination with high IQ. Meta-analysis of two studies, conducted on youthful high-IQ samples. demonstrated that high lifetime creative achievers had significantly lower LI scores than low creative achievers (r(effect size) = .31, p = .0003, one-tailed). Eminent creative achievers (participants under 21 years who reported unusually high scores in a single domain of creative achievement) were 7 times more likely to have low rather than high LI scores, chi2 (1, N = 25) = 10.69, phi = .47. p = .003.

Theory, methods and new directions in the psychophysiology of the schizophrenic process and schizotypy

Theoretical and methodological issues in the psychophysiology of the schizophrenic process are reviewed. These include the importance of schizotypy with its compensatory abilities as well as deficits for elucidating the processes of development and prevention of schizophrenia. The importance of individual differences, syndromes and single case studies. The recognition that this is a dynamic and fluctuating illness and hence the relevance of functional neurophysiology, including the role of imbalances in hemispheric activation in ontogeny, developmental course, expression of symptoms, the effects of neuroleptics and recovery process, and the influence of stress a precipitant of breakdown. The role of thalamo-cortical activation systems. The particular value of electrocortical measures including the interrelations of electroencephalographic rhythms throughout the spectrum, and relations of gamma, dynamic core neuronal complexity, connectivity and sensory gating with experiences of unreality and disturbances of consciousness.

Increased psychophysiological arousal and orienting at ages 3 and 11 years in persistently schizotypal adults

Abnormalities of psychophysiological arousal and orienting are thought to predispose to schizophrenia, but there have been no prior studies of early psychophysiological functioning in "persistent schizotypals" who remain stably schizotypal across time. This study assessed skin conductance (SC) arousal and orienting at ages 3 and 11 years, electroencephalography (EEG) at age 11 years, and behavior problems at age 17 years in 52 individuals who were stably schizotypal from ages 17 to 23 years, and 104 normal controls. Schizotypy was assessed at age 17 with the Schizophrenism scale, and at age 23 with the Schizotypal Personality Questionnaire (SPQ). Schizotypals had significantly increased SC arousal and increased SC amplitudes to neutral and aversive stimuli at both ages 3 and 11, and also reduced slow-wave left hemisphere EEG power at the beginning of the Continuous Performance Task (CPT) at age 11. Group differences in SC were greater for aversive than neutral stimuli. Schizotypals also had higher age 17 behavior ratings on psychotic behavior, anxiety-withdrawal, and conduct disorder. Findings indicate that heightened SC arousal and orienting in early childhood is a significant risk factor for later schizotypal personality, support a left hemisphere overactivation hypothesis of schizotypy, and illustrate the potential value of a longitudinal definition of persistent schizotypy.

Motor dysfunction in schizotypal personality disorder

Past research has revealed that schizophrenia is associated with voluntary movement abnormalities, as well as higher rates of involuntary movements. On instrumental motor tasks, patients manifest reduced motor stability, excessive force and more contralateral motor overflow (movement in the non-responding hand). In the present study, an instrumental motor task (manual response forced-choice task) was administered to a group of adults with schizotypal personality disorder (SPD) in order to determine whether they show motor deficits similar to those observed in schizophrenia. As predicted, the schizotypal subjects were excessive and more variable in motor force, compared to healthy controls and other personality-disordered subjects. Additionally, the force and variability of the motor responses were positively correlated with ratings of both positive and negative SPD symptoms. Finally, motor overflow and negative symptoms were associated with higher salivary cortisol levels. The pattern of findings is consistent with previous reports linking motor abnormalities and heightened cortisol with schizotypal personality disorder.

The relationship between skin conductance hyporesponsivity and perseverations in schizophrenia patients

BACKGROUND

It has been reported that approximately 45% of schizophrenia patients versus 10% of normal comparison subjects are classified as skin conductance hyporesponders (SCOR-HR: the lack of a robust orienting response) when exposed to innocuous tones. We studied the skin conductance orienting response (SCOR) of schizophrenia patients during the exposure to complex and abstract stimuli. We investigated two questions: 1) would the same percentage of schizophrenia patients be classified as SCOR-HR when the orienting stimuli are complex and abstract as when they are innocuous tones; and 2) whether SCOR-HR schizophrenia patients have associated frontally mediated neurocognitive deficits.

METHODS

Thirty-one schizophrenia patients and 29 normal comparison subjects were presented with the Rorschach inkblot test while their SCORs were recorded. Schizophrenics were divided in two groups: SCOR-HR and SCOR responders. Demographic and clinical comparisons were made between the two groups. Rorschach responses were scored for the presence of perseverations.

RESULTS

Forty-five percent of the schizophrenia patients were classified as SCOR-HR versus 10% of the normal comparison subjects. Among the schizophrenia patients, SCOR-HR was associated with increased perseverations, which were in turn correlated with the Scale for the Assessment of Negative Symptoms scores.

CONCLUSIONS

It appears that SCOR-HR in schizophrenia is not a function of the "meaningfulness" of the stimuli. When SCOR status was combined with the measure of stuck-in-set perseverations, a pattern of results emerged lending indirect support to the hypothesis that relates SCOR-HR to frontal impairment and to the idea that SCOR-HR schizophrenia patients may represent a specific subgroup.