Cognitive function and symptoms in adolescents with schizotypal personality disorder

Nabilone Impairs Spatial and Verbal Working Memory in Healthy Volunteers

Background: Memory impairments and psychosis-like experiences can be adverse effects of cannabis use. However, reports on the cognitive impact of cannabis use are not consistent. There are also limited studies on the psychotomimetic effects of cannabinoid compounds to reveal the association between cannabis and psychosis. Therefore, we investigated the effect of acute cannabinoid intoxication on verbal working memory (VWM) and spatial working memory (SWM) following oral doses of the synthetic cannabinoid agonist, nabilone (1-2 mg, oral). We further investigated the effect of nabilone on psychosis-like experiences (schizotypy scores) and associations of schizotypy with VWM and SWM. Methods: Healthy participants (n=28) completed spatial and digit span tasks across different delay conditions (0, 6, 12, and 18 sec) after receiving nabilone (1-2 mg, PO) or placebo in a randomized, double-blind, counterbalanced, crossover manner. A subset of participants completed a short battery of schizotypy measures (n=25). Results: Nabilone impaired VWM (p=0.03, weak effect size η2=0.02) and SWM (p=0.00016, η2=0.08). Nabilone did not significantly change overall schizotypy scores. Schizotypy scores were negatively correlated with working memory (WM) averaged across all delays and both modalities, under placebo (ρ=-0.41, p=0.04). In addition, there were significant negative correlations between occasions of cannabis use and overall WM averaged scores across drug treatments (ρ=-0.49, p=0.007) and under placebo (ρ=-0.45, p=0.004). The results showed that the drug effect in the less frequent cannabis users was more pronounced on the SWM (p<0.01) and VWM (p<0.01), whereas there appeared to be little drug effect in the frequent cannabis users. Conclusion: Low doses of synthetic cannabinoid impaired SWM and VWM, indicating that exogenous activation of the cannabinoid system influences cognitive performance. Further, the results replicated previous findings that schizotypy is correlated with deficits in WM. Clinical Trial Registry Name: Nabilone and caffeine effects on the perceptions of visually, auditory, tactile and multimodal illusions in healthy volunteers. Clinical Trial Registration Number: CT-2018-CTN-02561 (Therapeutic Goods Administration Clinical Trial Registry) and ACTRN12618001292268 (The Australian New Zealand Clinical Trials Registry).

The effects of caffeine and d-amphetamine on spatial span task in healthy participants

Studies that examined the effect of amphetamine or caffeine on spatial working memory (SWM) and verbal working memory (VWM) have used various tasks. However, there are no studies that have used spatial span tasks (SSTs) to assess the SWM effect of amphetamine and caffeine, although some studies have used digit span tasks (DST) to assess VWM. Previous reports also showed that increasing dopamine increases psychosis-like experiences (PLE, or schizotypy) scores which are in turn negatively associated with WM performance in people with high schizotypy and people with schizophrenia. Therefore, the present study aimed to examine the influence of d-amphetamine (0.45 mg/kg, PO), a dopamine releasing stimulant, on SST, DST, and on PLE in healthy volunteers. In a separate study, we examined the effect of caffeine, a nonspecific adenosine receptor antagonist with stimulant properties, on similar tasks.

METHODS

Healthy participants (N = 40) took part in two randomized, double-blind, counter-balanced placebo-controlled cross-over pilot studies: The first group (N = 20) with d-amphetamine (0.45 mg/kg, PO) and the second group (N = 20) with caffeine (200 mg, PO). Spatial span and digit span were examined under four delay conditions (0, 2, 4, 8 s). PLE were assessed using several scales measuring various aspects of psychosis and schizotypy.

RESULTS

We failed to find an effect of d-amphetamine or caffeine on SWM or VWM, relative to placebo. However, d-amphetamine increased a composite score of psychosis-like experiences (p = 0.0005), specifically: Scores on Brief Psychiatric Rating Scale, Perceptual Aberrations Scale, and Magical Ideation Scale were increased following d-amphetamine. The degree of change in PLE following d-amphetamine negatively and significantly correlated with changes in SWM, mainly at the longest delay condition of 8 s (r = -0.58, p = 0.006).

CONCLUSION

The present results showed that moderate-high dose of d-amphetamine and moderate dose of caffeine do not directly affect performances on DST or SST. However, the results indicate that d-amphetamine indirectly influences SWM, through its effect on psychosis-like experiences.

TRIAL REGISTRATION

CLINICAL TRIAL REGISTRATION NUMBER

CT-2018-CTN-02561 (Therapeutic Goods Administration Clinical Trial Registry) and ACTRN12618001292268 (The Australian New Zealand Clinical Trials Registry) for caffeine study, and ACTRN12608000610336 for d-amphetamine study.

Comparison of executive functions in individuals with high and low levels of schizotypal trait

The dimensional approach to Schizotypal Personality Disorder (SPD) indicates that SPD includes a constellation of maladaptive personality traits on a continuum with general personality functioning. This study aimed to compare executive functions (EFs) in low and high-level schizotypal individuals. Using a convenient sampling method, we recruited 120 individuals, from which 30 individuals with high schizotypal trait levels (fourth quartile) and 30 participants with lower schizotypal trait levels (first quartile) were selected based on their scores on the schizotypal personality disorder questionnaire. Then, participants from the two groups were administered the Corsi Block-Tapping Test (CBTT), Wisconsin Card Sorting Test (WCST), and Continuance Performance Test (CPT). The results indicated individuals with higher schizotypy trait levels performed significantly poorer in tasks measuring working-visual-spatial memory, cognitive flexibility, sustained attention, and response inhibition. This pattern of results indicated that EF dysfunctions in individuals with higher schizotypy trait levels would cause significant disturbances in multiple areas of life. The practical implications of the findings are further discussed.

Impact of self-reported cognitive dysfunction on the alternative model of personality disorders among older adults

METHOD

Older adults (N = 202) completed the Levels of Personality Functioning Scale-Self-Report, Personality Inventory for DSM-5, and Coolidge Axis II Inventory with its six self-report cognitive dysfunction scales.

RESULTS

Results suggested high correlational overlap between subjective cognitive problems with personality functioning and pathological personality, as measured by the AMPD. Hierarchical regressions revealed that subjective measures of executive functions, perceptual motor, and language difficulties were most strongly related to the AMPD's constructs. Results are discussed in the context of prior research on objective cognitive impairment among individuals with PDs.

CONCLUSION

The degree of overlap found within the current older adult sample suggested an age-related problem or potential age-bias, with older adults being at-risk of (a) having their subjective cognitive problems being incorrectly interpreted as personality pathology under the AMPD or (b) having personality pathology being overlooked under the AMPD, with symptoms instead attributed to subjective cognitive issues. This study suggested that subjective cognitive dysfunction may be one mechanism that contributes to differential performance of the AMPD among older adults.

Peer Problems and Low Self-esteem Mediate the Suspicious and Non-suspicious Schizotypy-Reactive Aggression Relationship in Children and Adolescents

The relationship between schizophrenia and violence has been well-established. Yet very little prior research exists on the factors that might explain the nature of this relationship and even fewer studies seek to clarify the etiology of aggressive behavior in adolescents with specific features of schizotypal personality that might help improve the specificity of intervention. The current study tested whether one dimension of schizotypy alone (i.e., the ‘suspicious’ feature) or the other 8 dimensions (i.e., the ‘non-suspicious’ features) were particularly associated with aggressive behaviors (reactive and proactive aggression), and if peer problems and low self-esteem mediated these relationships. A serial multiple mediation model testing the hypothesized flow from suspicious and non-suspicious schizotypy to peer problems to low self-esteem and to increased aggression was tested in Hong Kong schoolchildren aged 8- to 14-years (N = 1412; M_age = 11.47, SD = 1.67 years, female = 47.6%). Increased suspicious and non-suspicious schizotypal features were found to be independently associated with increased reactive aggression, but not proactive aggression. Children with high levels of suspicious schizotypy and non-suspicious schizotypy were more likely to have poor peer problems and low self-esteem concurrently, which in turn was associated with reactive aggression only. This explanatory model suggests that future longitudinal intervention studies that enhance self-esteem in schizotypal adolescents may potentially reduce co-morbid reactive aggressive behaviors too.

The effect of being left home alone at age 3 years on schizotypy and antisocial behavior at ages 17 and 23 years

OBJECTIVE

Negative home environments are associated with both schizophrenia-spectrum disorders and crime, but whether this is due to the social or cognitive sequelae of such environments is unclear. This study investigates the effect of early home environments on adult mental health.

METHOD

Using data from the Mauritius Child Health Project, a multiple time-point prospective study where all children born in 1969 in two towns (Quatre Bornes and Vacaos) were recruited at age 3 years (N = 1794), a group of children left home alone at age 3 (n = 34) were compared to children cared for by siblings/relatives (n = 222), or by mothers (n = 1498) on antisocial behavior and schizotypal personality at ages 11, 17, and 23 years.

RESULTS

Home alone children showed higher scores on psychotic behavior and conduct disorder at age 17, and also schizotypal personality and crime at 23 years compared to the other groups. No negative behavioral or cognitive effects were observed at age 11. Findings were not accounted for by social adversity or ethnicity and appear to be 'sleeper effects' in that they do not emerge until later adolescence and into adulthood.

CONCLUSIONS

Findings appear to be the first to show the negative effects of dual-parental daytime absence on adult schizotypy and crime, a finding that cannot be accounted for by verbal and spatial cognitive impairments. Results suggest an early common psychosocial denominator to the two comorbid conditions of antisocial behavior and schizotypy.

Lessons learned from research with adolescents with schizophrenia and their families

The purpose of this study is to present our experiences of conducting a randomized clinical trial of a self-management intervention for adolescents with schizophrenia and their families. Challenges and strategies of recruiting subjects; engaging families in self-management intervention; tailoring interventions for this population were discussed. Participants' comments on their experience were presented. Adolescents and their families are poorly prepared to manage schizophrenia; therefore psychosocial interventions should address their needs. Impaired cognitive functioning in adolescents with schizophrenia should be a target for interventions and should be considered in planning interventions.

Schizotypal traits and neurocognitive functioning among nonclinical young adults

Neurocognitive deficits and their relationship with symptoms have been documented in schizophrenia and at-risk samples. Limited research has examined relationships of schizotypal traits with cognitive functioning among nonclinical samples. To expand this literature and elucidate a dimensional model of psychosis-proneness, we examined the relationship of schizotypal traits with estimated intellectual functioning, simple and complex attention/working memory, verbal fluency and visuospatial abilities in a nonclinical sample of 63 young adults. As hypothesized, aspects of neurocognition were more closely associated with negative (than positive or disorganized) schizotypal traits. For the total sample, poorer visuospatial performance was associated with more negative and overall schizotypal traits. The magnitude of the majority of findings was strengthened after controlling for depression and anxiety. No other findings were significant. Results partially support Meehl's (1962, 1990) view that processes underlying schizophrenia are expressed along a continuum. Findings suggest a relationship of schizotypal traits with neurocognition that is differentiated by trait dimensions, beyond the contribution of general psychiatric symptoms. Findings have implications for better understanding etiology and potential risk factors for psychosis. While sex distribution did not enable direct examination of sex effects, evidence in the field argues for continued exploration of differential patterns by sex.

The relationship between personality disorders and Axis I psychopathology: deconstructing comorbidity

The purpose of this review is (a) to study and systematically review the recent literature examining the co-occurrence and relationships between Axis I psychiatric disorders and Axis II personality disorders, specifically the six originally proposed for the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5, and (b) to consider the clinical utility of the current Axis I and Axis II approach in the DSM-IV-TR and apply findings to state a position on the issue of collapsing together Axis I and Axis II. Community surveys or prospective cohort studies were reviewed as a priority. Our review indicates that the associations between clinical disorders and personality disorders clearly varied within each disorder and across the six personality disorders. Our understanding has advanced, particularly related to the clinical utility of comorbidity, and there may be sufficient evidence to support moving borderline personality disorder to Axis I. However, it seems premature to conclude that comorbidity is best conceptualized by having all disorders in a single category or by deleting disorders so that comorbidity is reduced. Our review suggests some priorities for future research into comorbidity, such as including personality disorders in future multivariate comorbidity models.

Peer victimization partially mediates the schizotypy-aggression relationship in children and adolescents

While persuasive evidence has accumulated over the past 15 years documenting an association between schizophrenia and violence, there are 3 unresolved issues. First, does a downward extension of this relationship exist at the nonclinical level with respect to schizotypal personality and aggression in children? Second, is aggression more associated with impulsive reactive aggression or with more planned proactive aggression. Third and importantly, does peer victimization mediate the relationship between schizotypy and aggression? A further aim of this cross-sectional study was to examine the utility of a new child self-report measure of schizotypal personality. These issues were examined in a sample of 3804 schoolchildren assessed on schizotypy using the Schizotypal Personality Questionnaire-Child (SPQ-C), reactive-proactive aggression, and peer victimization. A confirmatory factor analysis confirmed the 3-factor structure (cognitive-perceptual, interpersonal, and disorganized) of the SPQ-C. Schizotypy was positively associated with total aggression and reactive aggression but not with proactive aggression. Peer victimization was found to significantly mediate the schizotypy-aggression relationship, accounting for 58.9% of the association. Results are broadly consistent with the hypothesis that schizotypal features elicit victimization from other children, which in turn predisposes to reactive retaliatory aggression. Findings are to the authors' knowledge the first to document any mediator of the schizotypy-aggression relationship and have potential treatment implications for violence reduction in schizophrenia-spectrum disorders. This study also provides initial evidence for the factorial and discriminant validity of a brief and simple measure of schizotypal personality in children as young as 8 years.

Minor physical anomalies and vulnerability in prodromal youth

Because both the brain and craniofacial/limb features originate from the same germinal layer during early gestation, the postnatal presence of minor physical anomalies (MPAs) involving these physical features may be indicative of defects in prenatal neural migration and consequent brain abnormalities among individuals with psychosis. However, to date it is unknown what symptoms and characteristics MPAs may be associated with, or how these markers may reflect vulnerability among adolescents at high-risk for developing psychosis. This information is particularly vital for understanding susceptibility and informing etiological conceptualizations such as the neural diathesis-stress model. In this study, 50 adolescents with a prodromal syndrome were evaluated for MPAs, salivary cortisol, auditory and visual memory function, and attenuated positive, negative, and disorganized symptoms. Results indicated that the participants showing elevated MPAs (n=25) were distinguished by elevated cortisol, deficit immediate and delayed visual memory, and higher levels of disorganized prodromal symptoms when compared with those participants exhibiting a lower incidence of MPAs. This was supported by supplementary correlational analyses examining the entire sample. These findings provide preliminary support for a theory that MPAs may reflect hippocampal system vulnerability among prodromal patients.

Contribution of specific cognitive dysfunction to people with schizotypal personality

The current study aimed to determine whether there is a specific neurocognitive deficit in individuals with schizotypal personality features. One hundred and fifty-nine healthy participants and 62 schizotypal individuals completed a comprehensive battery of cognitive tests. The cognitive functions captured by the battery could be reduced to 6 factors. Significant difference was found between participants with schizotypal features and healthy controls in allocation, verbal memory and marginally in working memory. Schizotypal traits tended to correlate with some of the cognitive factors, especially allocation, verbal memory and working memory.

Catechol-O-methyltransferase modulation of cortisol secretion in psychiatrically at-risk and healthy adolescents

OBJECTIVE

Recent research implicates the catechol-O-methyltransferase (COMT) ValMet polymorphism in stress sensitivity, through modulation of hypothalamic-pituitary-adrenal (HPA) function. In healthy samples, Met homozygosity has been associated with greater HPA activity (i.e., cortisol) and stress sensitivity, though findings are mixed among clinical samples. To date, there are no reports examining baseline or longitudinal changes in HPA activity as a function of COMT genotype in youth. This study tested the hypothesis that COMT genotype would be associated with cortisol secretion in normal and at-risk adolescents; specifically, that COMT genotype would be linked in a dose-response manner such that Met homozygotes would have the highest salivary cortisol levels, followed by heterozygotes, then Val homozygotes. In addition, this study examined the relation of COMT genotype with longitudinal changes in cortisol.

METHODS

This study examined the association of COMT with salivary cortisol across a 1-year period in healthy and at-risk adolescents with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision Axis II diagnoses.

RESULTS

Results indicated higher cortisol levels for Met homozygotes (compared with heterozygotes and Val homozygotes) at the 1-year follow-up, and increased mean cortisol levels across a 1-year period among Met carriers, suggesting that COMT associates with differences in cortisol secretion during adolescence.

CONCLUSION

Findings are discussed with respect to COMT genotype as a potential genetic indicator of psychiatric risk that modulates developmental changes in HPA activity.

Markers of basal ganglia dysfunction and conversion to psychosis: neurocognitive deficits and dyskinesias in the prodromal period

BACKGROUND

Movement abnormalities and cognitive deficits may represent external markers of an underlying neural process linked with the early etiology of psychosis. As basal ganglia function plays a governing role in both movement and cognitive processes, an understanding of the relationship between these phenomena stands to inform etiologic conceptualizations of vulnerability and psychotic disorders.

METHODS

In this investigation, trained raters coded movement abnormalities in videotapes from structured interviews of adolescents and young adults with a prodromal risk syndrome (n = 90). The participants were administered a neuropsychological battery including measures of verbal comprehension, perceptual organization, immediate/delayed auditory memory, and an estimate of full-scale intelligence quotient. Diagnostic status was followed for a 2-year period utilizing structured clinical interviews, during which time 24 high-risk participants (26.66%) converted to an Axis I psychotic disorder.

RESULTS

Elevated dyskinetic movements in the upper-body region were correlated with deficits in domains of verbal comprehension, perceptual organization, and both immediate and delayed auditory memory. Further, discriminant function analyses indicated that baseline movement abnormalities and neurocognitive deficits significantly classified those high-risk participants who would eventually convert to a psychotic disorder (72.3%).

CONCLUSIONS

Results support a common cortico-striato-pallido-thalamic circuit irregularity, underlying both movement abnormalities and cognitive deficits in individuals at high risk for psychosis. Models incorporating external markers of progressive basal ganglia dysfunction may enhance detection and preventive intervention for those high-risk individuals most in need of treatment.

Cluster A Personality Disorders: Schizotypal, Schizoid and Paranoid Personality Disorders in Childhood and Adolescence

Cluster A personality disorders (PD), including schizotypal personality disorder (SPD), paranoid personality disorder (PPD), and schizoid PD, are marked by odd and eccentric behaviors, and are grouped together because of common patterns in symptomatology as well as shared genetic and environmental risk factors. The DSM-IV-TR describes personality disorders as representing stable and enduring patterns of maladaptive traits, and much of what is understood about Cluster A personality disorders in particular stems from research with adult populations. Less in known about these disorders in children and adolescents, and controversy remains regarding diagnosis of personality disorders in general in youth. The current paper reviews the available research on Cluster A personality disorders in childhood and adolescence; specifically, we discuss differentiating between the three disorders and distinguishing them from other syndromes, measuring Cluster A disorders in youth, and the nature and course of these disorders throughout childhood and adolescence. We also present recent longitudinal data from a sample of adolescents diagnosed with Cluster A personality disorders from our research laboratory, and suggest directions for future research in this important but understudied area.

Neurocognitive indicators of clinical high-risk states for psychosis: a critical review of the evidence

The present review investigates the empirical evidence from cross-sectional and long-term follow-up studies on neurocognitive indicators of an increased risk for developing schizophrenia spectrum psychoses in clinically defined high-risk samples. First, the investigations at the Cologne center for early recognition and intervention are briefly summarized and then integrated within the available literature. Thirty-two studies with original data could be identified by extensive literature search. Cross-sectional investigations of neurocognitive baseline assessments in high-risk samples with unknown conversion status have produced rather inconsistent results. Nevertheless, most convincing evidence could be collected for abnormal functioning in processing speed measures (digit symbol coding, Trailmaking Test-B, Stroop Color Naming), the Continuous Performance Test, verbal working memory measures, verbal memory and learning, and verbal fluency, though negative findings have also been reported in every instance. Moreover, high-risk subjects were found to perform both at the schizophrenia performance level and at a close to normal level. Longitudinal follow-up assessments provided predictive evidence with regard to psychosis conversion for measures of processing speed and of verbal memory and learning. However, a substantial number of negative findings does not allow for straight-forward conclusions. Finally, some reasons for inconsistent findings are discussed critically speculating on demographic differences, reliability and sample sizes, and conceptual imprecision in communicating results.

Schizotypal traits and cognitive function in healthy adults

Growing evidence has shown that psychometrically identified schizotypes among student populations have subtle cognitive impairments in several domains such as attention, working memory and executive function, but the possible association between psychometric schizotypy in adult populations and cognitive function has not been well documented. Here we examined the association between schizotypal traits as assessed by the Schizotypal Personality Questionnaire (SPQ) and cognitive function including memory, attention, executive function, and general intelligence in 124 healthy adults. Cognitive functioning was assessed with the Wechsler Memory Scale-Revised (WMS-R), the Wechsler Adult Intelligence Scale-Revised (WAIS-R), and the Wisconsin Card Sorting Test (WCST). SPQ scores showed a significant inverse correlation with verbal IQ and the information, comprehension and similarities subtests. No correlation was found between SPQ scores and memory, attention, performance IQ, or executive functioning. These results indicate that schizotypal traits in healthy adults are associated with verbal IQ decrements, suggesting that schizotypal traits themselves, even at a non-clinical level, may play unfavorable roles in cognitive functioning, which is in line with the viewpoint that schizotypy is on a continuum with normality, with its extreme form being clinically expressed as schizophrenia.

Neurocognition and conversion to psychosis in adolescents at high-risk

This study examined neurocognitive predictors of conversion to Axis I psychosis among adolescents at high-risk for psychosis (AHRP). There were no significant differences in neurocognitive performance between adolescents at high-risk for psychosis who converted (AHRP+) and adolescents at high-risk for psychosis who did not convert (AHRP-). Within-sex comparisons revealed a relation between risk status and performance among females, with AHRP+ performing below AHRP-, but this effect did not hold for males. Between-sex comparisons revealed AHRP- males performed worse than AHRP- females on several measures. Across groups, males performed better than their female counterparts on select measures. Results are discussed in terms of implications for use of neurocognitive profiles as bio-risk markers of psychosis, while considering sex differences.

The "close-in" or ultra high-risk model: a safe and effective strategy for research and clinical intervention in prepsychotic mental disorder

The development of a new frontier for research and early intervention in psychotic disorders is highly dependent on the construction of synergistic clinical infrastructures. This has catalyzed great progress in the recognition, enhanced treatment, and study of first episode psychosis, and the task is even more challenging when the boundaries are extended to include the earliest clinical phase of illness, the prodromal or prepsychotic phase. This article describes the conceptual and practical building blocks for the construction of service models for intervention in the postonset clinical phase prior to the attainment of current diagnostic thresholds. This is best regarded as indicated prevention, a form of very early secondary prevention, which involves a blend of immediate clinical care combined with research-oriented preventive intervention. The experience of the Personal Assessment and Crisis Evaluation (PACE) Clinic in Melbourne across several stages of growth is described and contrasted with that of several emerging centers in Europe and North America. The progress to date, the lessons learned, and the unresolved challenges and opportunities are detailed. It is concluded that service models can be developed that are acceptable and helpful to young people and their families, and that create a unique environment for the study of the transition to frank psychotic disorder. The ultimate clinical utility and general safety of this approach and the range of effective treatments remain unclear, and will be determined by more extensive research. Such research must be conducted in a logical and rigorous manner with the best designs possible, sensitive to input from consumers and caregivers and to ethical considerations.