Schizotaxia: current status and future directions

Schizophrenia Imaging Signatures and Their Associations With Cognition, Psychopathology, and Genetics in the General Population

OBJECTIVE

The prevalence and significance of schizophrenia-related phenotypes at the population level is debated in the literature. Here, the authors assessed whether two recently reported neuroanatomical signatures of schizophrenia-signature 1, with widespread reduction of gray matter volume, and signature 2, with increased striatal volume-could be replicated in an independent schizophrenia sample, and investigated whether expression of these signatures can be detected at the population level and how they relate to cognition, psychosis spectrum symptoms, and schizophrenia genetic risk.

METHODS

This cross-sectional study used an independent schizophrenia-control sample (N=347; ages 16-57 years) for replication of imaging signatures, and then examined two independent population-level data sets: typically developing youths and youths with psychosis spectrum symptoms in the Philadelphia Neurodevelopmental Cohort (N=359; ages 16-23 years) and adults in the UK Biobank study (N=836; ages 44-50 years). The authors quantified signature expression using support-vector machine learning and compared cognition, psychopathology, and polygenic risk between signatures.

RESULTS

Two neuroanatomical signatures of schizophrenia were replicated. Signature 1 but not signature 2 was significantly more common in youths with psychosis spectrum symptoms than in typically developing youths, whereas signature 2 frequency was similar in the two groups. In both youths and adults, signature 1 was associated with worse cognitive performance than signature 2. Compared with adults with neither signature, adults expressing signature 1 had elevated schizophrenia polygenic risk scores, but this was not seen for signature 2.

CONCLUSIONS

The authors successfully replicated two neuroanatomical signatures of schizophrenia and describe their prevalence in population-based samples of youths and adults. They further demonstrated distinct relationships of these signatures with psychosis symptoms, cognition, and genetic risk, potentially reflecting underlying neurobiological vulnerability.

Psychotic conversion of individuals at ultra-high risk for psychosis: The potential roles of schizotypy and basic symptoms

AIM

To improve strategies for the early identification of individuals at a heightened risk for the development of psychosis, we investigated the relationships and interactions between 3 psychosis-proneness dimensions for the development of schizophrenia spectrum psychosis: schizotypy, basic symptoms and the ultra-high risk (UHR) criteria.

METHODS

Seventy-seven UHR individuals and 79 healthy controls were assessed for schizotypy and basic symptoms using self-report questionnaires at baseline. UHR participants were monthly assessed for conversion to psychosis over a mean period of 25.8 months.

RESULTS

Sixteen UHR participants (20.8%) converted to schizophrenia spectrum psychosis. In stepwise Cox regression, the interaction between basic symptoms and physical anhedonia was selected as a sole predictor of conversion in UHR participants, whereby the self-reported number of the 8 basic symptoms significantly increased the risk for conversion in those with pronounced physical anhedonia.

CONCLUSION

Our findings suggest that questionnaire-assessed basic symptoms, irrespective of their predictive validity, may predict a psychotic breakdown in pre-identified UHR individuals who are with genetic vulnerability to schizophrenia. Including all 3 psychosis-proneness dimensions into prediction models might help establish a more valid pathogenetic model of schizophrenia, and moreover, may provide some clues about course alteration strategies in hopes of preventing UHR individuals from converting to psychosis.

A developmentally-stable pattern of premorbid schizoid-schizotypal features predicts psychotic transition from the clinical high-risk for psychosis state

BACKGROUND

Despite the extensive research performed on prediction of psychosis from a Clinical High Risk for Psychosis state (CHR-P), the positive predictive value of the CHR-P designation remains unsatisfactory and further models including additional clinical and biological variables are required. Existing studies indicate that schizotypy assessed at baseline in "at-risk" individuals may be considered a predictor of transition from CHR-P to psychosis. This approach, however, is burdened with bias resulting from a possible overlap between current psychopathology and schizotypal features. No studies so far have assessed schizotypy in CHR-P from a developmental perspective.

AIM

The aim of the study was to identify associations between a long-standing, parent-reported premorbid level of schizoid-schizotypal traits and the probability of psychotic transition in individuals with CHR-P.

METHODS

The mothers of 107 individuals diagnosed as presenting CHR-P with the use of Comprehensive Assessment of At Risk Mental States12/2006 were interviewed with the Scale for the Assessment of Premorbid Schizoid-Schizotypal Traits (PSST).

RESULTS

A high level of enduring schizotypy was found to be significantly associated with psychotic transition from CHR-P (HR: 1.78, 95% CI: 1.40-2.27, p < 0.0001), as indicated by the proportional hazards model, adjusted for age, sex and clinical covariates potentially related to the outcome. PSST items comprising negative schizotypy appeared to be the strongest predictors of transition.

CONCLUSIONS

The assessment of parent-reported, present early in the development premorbid schizoid-schizotypal traits, which can be easily performed in clinical settings, may be of value in estimating the probability of transition from an "at risk" state to psychotic disorder.

Childhood maltreatment and transition to psychotic disorder independently predict long-term functioning in young people at ultra-high risk for psychosis

BACKGROUND

Individuals identified as at ultra-high risk (UHR) for psychosis are at risk of poor functional outcome regardless of development of psychotic disorder. Studies examining longitudinal predictors of poor functioning have tended to be small and report only medium-term follow-up data. We sought to examine clinical predictors of functional outcome in a long-term longitudinal study.

METHOD

Participants were 268 (152 females, 116 males) individuals identified as UHR 2-14 years previously. A range of clinical and sociodemographic variables were assessed at baseline. Functioning at follow-up was assessed using the Social and Occupational Functioning Assessment Scale (SOFAS).

RESULTS

Baseline negative symptoms, impaired emotional functioning, disorders of thought content, low functioning, past substance use disorder and history of childhood maltreatment predicted poor functioning at follow-up in univariate analyses. Only childhood maltreatment remained significant in the multivariate analysis (p < 0.001). Transition to psychosis was also significantly associated with poor functioning at long-term follow-up [mean SOFAS score 59.12 (s.d. = 18.54) in the transitioned group compared to 70.89 (s.d. = 14.00) in the non-transitioned group, p < 0.001]. Childhood maltreatment was a significant predictor of poor functioning in both the transitioned and non-transitioned groups.

CONCLUSIONS

Childhood maltreatment and transition to psychotic disorder independently predicted poor long-term functioning. This suggests that it is important to assess history of childhood maltreatment in clinical management of UHR individuals. The finding that transition to psychosis predicts poor long-term functioning strengthens the evidence that the UHR criteria detect a subgroup at risk for schizophrenia.

Quality of life of key caregivers of schizophrenia patients and association with kinship

INTRODUCTION

Reports on the quality of life (QOL) of family caregivers of schizophrenia patients are uncommon. Relations of different degree of kinship to caregivers' QOL are unexplored, but may be relevant. The purpose of this study was to assess the subjective QOL of caregivers of stable outpatients with diagnosis of schizophrenia compared with controls, and to assess factors associated with QOL in this population.

METHODS

Responses of 138 schizophrenia outpatient' family caregivers to the Quality of Life, Enjoyment and Satisfaction Questionnaire (QLESQSF) were compared with those of a sex- and age-matched control group. Patients were assessed with the Positive and Negative Symptom Scale (PANSS) and the Global Assessment of Functioning (GAF) and data were collected for kinship relationship and hospitalization.

RESULTS

Group of caregivers had significantly lower QOL compared with controls (t=11.347; df=271; p=0.0001). Caregivers' QOL correlated significantly with their age and differed according to the degree of kinship and marriage status. ANCOVA, with age as covariate, performed to asses the differences in QOL according to kinship, showed that parents and own children had significantly lower QOL than patients' siblings who were also caregivers.

CONCLUSION

QOL of the schizophrenia patients' caregivers is lower in comparisons to controls. It depends on the degree of kinship and caregivers' age. Parents and own children have lower QOL than siblings. Psycho-educational intervention programmes should target specific needs of the family as a whole, depending also on their age and kinship relationship.

Exophenotypical profile of adolescents with sustained attention deficit: A 10-year follow-up study

We aimed to explore prospectively the relationship between the presence of sustained attention deficit (SAD) in early adolescence and exophenotypical measures of vulnerability to schizophrenia spectrum disorders (personality and psychosocial measures) in early adulthood. Two cohorts of community adolescents were selected in 1993 according to the presence or absence of a CPT-linked SAD. In 2003, both cohorts (Index: n=42, and

CONTROL

n=38) were administered the O-LIFE, the SCID-II, the DOI battery and the COPE scale, among other tests. T-tests were used to compare both cohorts. Index subjects showed a higher level of negative schizotypy, avoidant, depressive and narcissistic personality traits, as well as more asocial behavior and poorer use of coping resources than CONTROL subjects did. A SAD in early adolescence may be associated with coping and social deficits, negative schizotypy, and personality traits indicative of emotional disturbance in adulthood. Our results suggest that SAD in early adolescence might be an indicator of psychopathology in adulthood and give support to dimensional models of psychopathology.

Hallucinatory experiences, delusional thought proneness, and psychological distress in a nonclinical population

Despite evidence that the reporting of delusion-like or hallucinatory experiences are predictive of the future development of a mental disorder in the spectrum of psychosis, the exact nature of such a kind of unusual subjective experience in the general population is still disputed. We investigated the multidimensionality of these experiences with the Peters et al. Delusions Inventory (PDI) and a modified Italian version of the Launay-Slade Hallucination Scale (LSHS-R) in 250 subjects of both genders drawn from the normal population, using the General Health Questionnaire (GHQ) as a measure of psychic distress of a clinically relevant nature. We found that GHQ scores are positively related to both the PDI and the LSHS-R scores, but the GHQ did not act as a mediator in the links between the 2 psychosis-proneness measures. Conversely, the LSHS-R scores fully mediated the links between GHQ and PDI scores. It can be argued that hallucination proneness and psychosis proneness do not overlap in the nonclinical population but can both cause distress separately.

Predicting quality of life impairment in chronic schizophrenia from cognitive variables

BACKGROUND

The aim of this study was to see whether and how cognition deficit predicts quality of life impairments in schizophrenia patients.

METHOD

The Computerized Cambridge Automated Neuropsychological Test Battery, the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q) and the Quality of Life Scale (QLS) were used to assess 62 patients with chronic schizophrenia. Step-wise multiple regression analysis was used in order to determine cognitive variables that would predict the scores of each Q-LES-Q and QLS domain scores.

RESULTS

Regression analysis revealed a significant association of the cognitive deficits with both general and domain-specific quality of life impairment measured with Q-LES-Q and QLS. Deficits in executive functions, visual sustained attention, memory and motor skills have been found to be valid predictors both before and after controlling for the severity of symptoms, emotional distress, side effects, age, education, and illness duration.

CONCLUSIONS

This study suggests that deficits in executive functioning, attention, memory and motor skills substantially contributes to predicting impairments across a wide range of HRQL domains, and, consequently, to quality of life appraisal in schizophrenia. Cognitive predictors cannot be attributed to illness-related and background variables. It can be concluded that, when aiming at the improvement of quality of life in schizophrenia patients, cognitive functioning should be targeted.