Cognitive impairment among children at-risk for schizophrenia

Speech characteristics yield important clues about motor function: Speech variability in individuals at clinical high-risk for psychosis

BACKGROUND AND HYPOTHESIS

Motor abnormalities are predictive of psychosis onset in individuals at clinical high risk (CHR) for psychosis and are tied to its progression. We hypothesize that these motor abnormalities also disrupt their speech production (a highly complex motor behavior) and predict CHR individuals will produce more variable speech than healthy controls, and that this variability will relate to symptom severity, motor measures, and psychosis-risk calculator risk scores.

STUDY DESIGN

We measure variability in speech production (variability in consonants, vowels, speech rate, and pausing/timing) in N = 58 CHR participants and N = 67 healthy controls. Three different tasks are used to elicit speech: diadochokinetic speech (rapidly-repeated syllables e.g., papapa…, pataka…), read speech, and spontaneously-generated speech.

STUDY RESULTS

Individuals in the CHR group produced more variable consonants and exhibited greater speech rate variability than healthy controls in two of the three speech tasks (diadochokinetic and read speech). While there were no significant correlations between speech measures and remotely-obtained motor measures, symptom severity, or conversion risk scores, these comparisons may be under-powered (in part due to challenges of remote data collection during the COVID-19 pandemic).

CONCLUSION

This study provides a thorough and theory-driven first look at how speech production is affected in this at-risk population and speaks to the promise and challenges facing this approach moving forward.

The Risk for Schizophrenia-Bipolar Spectrum: Does the Apple Fall Close to the Tree? A Narrative Review

Schizophrenia (SCZ) and bipolar disorder (BD) are severe psychiatric disorders that share clinical features and several risk genes. Important information about their genetic underpinnings arises from intermediate phenotypes (IPs), quantifiable biological traits that are more prevalent in unaffected relatives (RELs) of patients compared to the general population and co-segregate with the disorders. Within IPs, neuropsychological functions and neuroimaging measures have the potential to provide useful insight into the pathophysiology of SCZ and BD. In this context, the present narrative review provides a comprehensive overview of the available evidence on deficits in neuropsychological functions and neuroimaging alterations in unaffected relatives of SCZ (SCZ-RELs) and BD (BD-RELs). Overall, deficits in cognitive functions including intelligence, memory, attention, executive functions, and social cognition could be considered IPs for SCZ. Although the picture for cognitive alterations in BD-RELs is less defined, BD-RELs seem to present worse performances compared to controls in executive functioning, including adaptable thinking, planning, self-monitoring, self-control, and working memory. Among neuroimaging markers, SCZ-RELs appear to be characterized by structural and functional alterations in the cortico-striatal-thalamic network, while BD risk seems to be associated with abnormalities in the prefrontal, temporal, thalamic, and limbic regions. In conclusion, SCZ-RELs and BD-RELs present a pattern of cognitive and neuroimaging alterations that lie between patients and healthy individuals. Similar abnormalities in SCZ-RELs and BD-RELs may be the phenotypic expression of the shared genetic mechanisms underlying both disorders, while the specificities in neuropsychological and neuroimaging profiles may be associated with the differential symptom expression in the two disorders.

Dissociable impairments of verbal learning differentiate childhood risk profiles for schizophrenia

Poor verbal learning and memory function is well-documented among individuals with schizophrenia and those at clinical high-risk for psychosis. This study aimed to identify these impairments among children aged 9–12 years with different schizophrenia risk profiles (family history or antecedents of schizophrenia, each of higher^[H] or lower^[L] risk load) relative to typically developing peers. These three groups were recruited via community-screening, and differentiated for analysis into: typically developing children (TD = 45); children who had 1 first- or ≥2 second-degree affected relatives (FHx^H = 16) or one second-degree relative (FHx^L = 15); and children presenting multiple replicated antecedents of schizophrenia whose clinical symptoms persisted at 2- and/or 4-year follow-up (ASz^H = 16) or remitted during follow-up (ASz^L = 16). Verbal learning/memory measures assessed at baseline (age 9–12 years) included: (i) total recall; (ii) trial 1 recall; (iii) learning score; (iv) intrusions; (v) total words lost; and (vi) serial position patterns. Analyses of variance indicated that FHx^H and ASz^H youth demonstrated impaired total recall compared to TD and ASz^L children and lost significantly more words between trials than TD and FHx^L children. Learning score was impaired among both FHx^H and FHx^L relative to TD and ASz^L children. Thus, among putatively at-risk children, total words recalled and lost distinguished those with higher risk load (by family history or persistent antecedent symptomology), whereas learning score indexed familial vulnerability. Follow-up of the sample is needed to determine the capacity of verbal learning deficits to predict later illness and provide a potential avenue for early remediation to improve clinical or functional outcomes.

Adolescent Verbal Memory as a Psychosis Endophenotype: A Genome-Wide Association Study in an Ancestrally Diverse Sample

Verbal memory impairment is one of the most prominent cognitive deficits in psychosis. However, few studies have investigated the genetic basis of verbal memory in a neurodevelopmental context, and most genome-wide association studies (GWASs) have been conducted in European-ancestry populations. We conducted a GWAS on verbal memory in a maximum of 11,017 participants aged 8.9 to 11.1 years in the Adolescent Brain Cognitive Development Study®, recruited from a diverse population in the United States. Verbal memory was assessed by the Rey Auditory Verbal Learning Test, which included three measures of verbal memory: immediate recall, short-delay recall, and long-delay recall. We adopted a mixed-model approach to perform a joint GWAS of all participants, adjusting for ancestral background and familial relatedness. The inclusion of participants from all ancestries increased the power of the GWAS. Two novel genome-wide significant associations were found for short-delay and long-delay recall verbal memory. In particular, one locus (rs9896243) associated with long-delay recall was mapped to the NSF (N-Ethylmaleimide Sensitive Factor, Vesicle Fusing ATPase) gene, indicating the role of membrane fusion in adolescent verbal memory. Based on the GWAS in the European subset, we estimated the SNP-heritability to be 15% to 29% for the three verbal memory traits. We found that verbal memory was genetically correlated with schizophrenia, providing further evidence supporting verbal memory as an endophenotype for psychosis.

Trajectories of Mismatch Negativity and P3a Amplitude Development From Ages 9 to 16 Years in Children With Risk Factors for Schizophrenia

BACKGROUND

Mismatch negativity (MMN) and P3a amplitude reductions are robust abnormalities of sensory information processing in schizophrenia, but they are variably present in different profiles of risk (family history vs. clinical high risk) for the disorder. This study aimed to determine whether these abnormalities characterize children presenting replicated risk factors for schizophrenia, using longitudinal assessment over the ages of 9-16 years in children with multiple replicated antecedents of schizophrenia (ASz) and with family history of schizophrenia (FHx), relative to typically developing (TD) peers.

METHODS

A total of 105 children (52 female) sampled from the community were assessed at ages 9-12 years and approximately 2 and 4 years later. Linear mixed models were fitted to MMN and P3a peak amplitudes and latencies, with intercept and slope estimates from 32 ASz and 28 FHx children compared with those of 45 TD peers.

RESULTS

In ASz relative to TD children, MMN amplitude initially increased and then prominently decreased during adolescence. Both ASz and FHx children had greater P3a amplitude than TD children at 11 years, which decreased with age, in contrast to P3a amplitude increasing during adolescence in TD youths. MMN abnormalities were specific to ASz children who continued to present symptoms during follow-up.

CONCLUSIONS

Age-dependent MMN and P3a abnormalities demarcate adolescent development of ASz and FHx from TD children, with auditory change detection abnormalities specific to ASz children with continuing symptoms and attention-orienting abnormalities characterizing both ASz and FHx risk profiles. Follow-up is required to determine whether these abnormalities index vulnerability for schizophrenia or an illness nonspecific developmental delay.

Academic achievement and schizophrenia: a systematic meta-analysis

BACKGROUND

Cognitive impairments in childhood are associated with increased risk of schizophrenia in later life, but the extent to which poor academic achievement is associated with the disorder is unclear.

METHODS

Major databases were searched for articles published in English up to 31 December 2019. We conducted random-effects meta-analyses to: (1) compare general academic and mathematics achievement in youth who later developed schizophrenia and those who did not; (2) to examine the association between education level achieved and adult-onset schizophrenia; and, (3) compare general academic achievement in youth at-risk for schizophrenia and typically developing peers. Meta-regression models examined the effects of type of academic assessment, educational system, age at assessment, measurement of educational level attained, school leaving age, and study quality on academic achievement and education level among individuals with schizophrenia.

RESULTS

Meta-analyses, comprising data of over four million individuals, found that: (1) by age 16 years, those who later developed schizophrenia had poorer general academic (Cohen's d = -0.29, p ⩽ 0.0001) and mathematics achievement (d = -0.23, p = 0.01) than those who did not; (2) individuals with schizophrenia were less likely to enter higher education (odds ratio = 0.49, p ⩽ 0.0001); and, (3) youth reporting psychotic-like experiences and youth with a family history of schizophrenia had lower general academic achievement (d = -0.54, p ⩽ 0.0001; d = -0.39, p ⩽ 0.0001, respectively). Meta-regression analyses determined no effect modifiers.

DISCUSSION

Despite significant heterogeneity across studies, various routinely collected indices of academic achievement can identify premorbid cognitive dysfunction among individuals who are vulnerable for schizophrenia, potentially aiding the early identification of risk in the population.

Neuropsychological profile of children and adolescents with psychosis risk syndrome: the CAPRIS study

Neuropsychological underperformance is well described in young adults at clinical high risk for psychosis, but the literature is scarce on the cognitive profile of at-risk children and adolescents. The aim of this study is to describe the neuropsychological profile of a child and adolescent sample of patients with psychosis risk syndrome (PRS) compared to healthy controls and to analyze associations between attenuated psychotic symptoms and cognitive impairment. Cross-sectional baseline data analysis from a longitudinal, naturalistic, case-control, two-site study is presented. Eighty-one help-seeking subjects with PRS and 39 healthy controls (HC) aged between 10 and 17 years of age were recruited. PRS was defined by: positive or negative attenuated symptoms, Brief Limited Intermittent Psychotic Symptoms (BLIPS), genetic risk (first- or second-degree relative), or schizotypal personality disorder plus impairment in functioning. A neuropsychological battery was administered to assess general intelligence, verbal and visual memory, visuospatial abilities, speed processing, attention, and executive functions. The PRS group showed lower general neuropsychological performance scores at a multivariate level and lower scores than controls in general intelligence and executive functions. Lower scores on executive function and poorer attention were associated with high scores of positive attenuated psychotic symptoms. No association with attenuated negative symptoms was found. This study provides evidence of cognitive impairment in PRS children and adolescents and shows a relationship between greater cognitive impairment in executive functions and attention tasks and severe attenuated positive symptoms. However, longitudinal studies are needed to clarify the nature of cognitive impairment as a possible vulnerability marker.

Detecting motor slowing in clinical high risk for psychosis in a computerized finger tapping model

Finger tapping is sensitive to motor slowing and emerging symptoms in individuals at clinical high risk for psychosis (CHR). A sensitive, computerized finger tapping task would be beneficial in early psychosis screening batteries. The study included 41 CHR and 32 healthy volunteers, who completed a computerized finger tapping task and clinical interviews. This computerized finger tapping task was sensitive to slowing in the CHR group compared to healthy volunteers, and as expected negative but not positive symptoms related to motor slowing. Computerized finger tapping tasks may be an easily dispersible tool for early symptom detection battery relevant to emerging negative symptoms.

Adolescent trajectories of fine motor and coordination skills and risk for schizophrenia

Premorbid motor dysfunction is one of the earliest of developmental antecedents identified among individuals who develop schizophrenia in adulthood. However, among individuals with schizophrenia, premorbid motor dysfunction is not apparent at all stages of childhood development and may reduce with increasing age. Currently, little is known about the trajectories of motor development during adolescence among youth at-risk for the disorder. One hundred and one participants were assessed repeatedly, at approximately 24-month intervals (time 1, aged 9-12 years; time 2, 11-14 years; and time 3, 13-16 years), on the Purdue Pegboard assessment, comprising four subtests: Dominant Hand (DH), Non-Dominant Hand (NDH), Both Hands (BH), and Assembly. Fine motor and coordination skills development between ages 9-16 years was compared between youth characterised by a triad of developmental antecedents of schizophrenia (ASz, N = 32); youth with at least one affected relative with schizophrenia/schizoaffective disorder (FHx; N = 26); and typically developing youth without antecedents or family history (TD, N = 43). Longitudinal mixed models for repeated measures indicated significant motor skills improvements with age in TD youth on the Assembly subtest only. Relative to TD youth, we found evidence for developmental deficits (i.e., dysfunction that emerged early and remained stable) among ASz youth on DH and BH subtests, and among FHx youth on the Assembly subtest. ASz youth were characterised by a developmental delay on the Assembly subtest (i.e., initial performance decrement in middle childhood that caught up with peers' performance during adolescence). These divergences from normative motor development may reflect differences in structural and functional neural correlates.

Association of genetic variants at 22q11.2 chromosomal region with cognitive performance in Japanese patients with schizophrenia

22q11.2 heterozygous multigene deletions confer an increased risk of schizophrenia with marked impairment of cognition. We explored whether genes on 22q11.2 are associated with cognitive performance in patients with idiopathic schizophrenia. A total of 240 schizophrenia patients and 240 healthy controls underwent the Japanese-language version of the Brief Assessment of Cognition in Schizophrenia (BACS) and were genotyped for 115 tag single-nucleotide polymorphisms (tag SNPs) at the 22q11.2 region using the golden gate assay (Illumina®). Associations between z-scores of the BACS cognitive domains and SNPs and haplotypes were analyzed using linear regression in PLINK 1.07. An additional set of 149 patients with bipolar disorder were included for cognitive assessment and selected SNPs were genotyped using real-time PCR. Patients with schizophrenia and bipolar disorder showed qualitatively comparable profiles of cognitive impairment across BACS subdomains, as revealed by significant correlation between the two groups in the resulting cognitive effect sizes relative to controls. rs4819522 (TBX1) and rs2238769 (UFD1L) were significantly and nominally associated, respectively, with symbol coding in patients with schizophrenia. Haplotype analyses revealed that haplotypes containing the A allele at rs4819522 and G allele at rs2238769 showed significant negative associations with symbol coding in patients with schizophrenia. There was no effect of any haplotypes on cognition in patients with bipolar disorder. Our results have implications for the understanding of the role of haplotypes of UFD1L and TBX1 genes associated with symbol coding in patients with schizophrenia. Further replication studies in a cohort of newly diagnosed patients and other ethnicities are warranted.

Trajectories of cognitive development during adolescence among youth at-risk for schizophrenia

BACKGROUND

Among adults with schizophrenia, evidence suggests that premorbid deficits in different cognitive domains follow distinct developmental courses during childhood and adolescence. The aim of this study was to delineate trajectories of adolescent cognitive functions prospectively among different groups of youth at-risk for schizophrenia, relative to their typically developing (TD) peers.

METHOD

Using linear mixed models adjusted for sex, ethnicity, parental occupation and practice effects, cognitive development between ages 9 and 16 years was compared for youth characterised by a triad of well-replicated developmental antecedents of schizophrenia (ASz; N = 32) and youth with a least one affected relative with schizophrenia or schizoaffective disorder (FHx; N = 29), relative to TD youth (N = 45). Participants completed measures of IQ, scholastic achievement, memory and executive function at three time-points, separated by approximately 24-month intervals.

RESULTS

Compared to TD youth, both ASz and FHx youth displayed stable developmental deficits in verbal working memory and inhibition/switching executive functions. ASz youth additionally presented with stable deficits in measures of vocabulary (IQ), word reading, numerical operations, and category fluency executive function, and a slower rate of growth (developmental lag) on spelling from 9 to 16 years than TD peers. Conversely, faster rates of growth relative to TD peers (developmental delay) were observed on visual and verbal memory, and on category fluency executive function (ASz youth only) and on matrix reasoning (IQ) and word reading (FHx youth only).

CONCLUSIONS

These differential patterns of deviation from normative adolescent cognitive development among at-risk youth imply potential for cognitive rehabilitation targeting of specific cognitive deficits at different developmental phases.

Cognitive Deficits in Psychotic Disorders: A Lifespan Perspective

Individuals with disorders that include psychotic symptoms (i.e. psychotic disorders) experience broad cognitive impairments in the chronic state, indicating a dimension of abnormality associated with the experience of psychosis. These impairments negatively impact functional outcome, contributing to the disabling nature of schizophrenia, bipolar disorder, and psychotic depression. The robust and reliable nature of cognitive deficits has led researchers to explore the timing and profile of impairments, as this may elucidate different neurodevelopmental patterns in individuals who experience psychosis. Here, we review the literature on cognitive deficits across the life span of individuals with psychotic disorder and psychotic-like experiences, highlighting the dimensional nature of both psychosis and cognitive ability. We identify premorbid generalized cognitive impairment in schizophrenia that worsens throughout development, and stabilizes by the first-episode of psychosis, suggesting a neurodevelopmental course. Research in affective psychosis is less clear, with mixed evidence regarding premorbid deficits, but a fairly reliable generalized deficit at first-episode, which appears to worsen into the chronic state. In general, cognitive impairments are most severe in schizophrenia, intermediate in bipolar disorder, and the least severe in psychotic depression. In all groups, cognitive deficits are associated with poorer functional outcome. Finally, while the generalized deficit is the clearest and most reliable signal, data suggests specific deficits in verbal memory across all groups, specific processing speed impairments in schizophrenia and executive functioning impairments in bipolar disorder. Cognitive deficits are a core feature of psychotic disorders that provide a window into understanding developmental course and risk for psychosis.

Hot and cold executive functions in youth with psychotic symptoms

BACKGROUND

Psychotic symptoms are common in children and adolescents and may be early manifestations of liability to severe mental illness (SMI), including schizophrenia. SMI and psychotic symptoms are associated with impairment in executive functions. However, previous studies have not differentiated between 'cold' and 'hot' executive functions. We hypothesized that the propensity for psychotic symptoms is specifically associated with impairment in 'hot' executive functions, such as decision-making in the context of uncertain rewards and losses.

METHODS

In a cohort of 156 youth (mean age 12.5, range 7-24 years) enriched for familial risk of SMI, we measured cold and hot executive functions with the spatial working memory (SWM) task (total errors) and the Cambridge Gambling Task (decision-making), respectively. We assessed psychotic symptoms using the semi-structured Kiddie Schedule for Affective Disorders and Schizophrenia interview, Structured Interview for Prodromal Syndromes, Funny Feelings, and Schizophrenia Proneness Instrument - Child and Youth version.

RESULTS

In total 69 (44.23%) youth reported psychotic symptoms on one or more assessments. Cold executive functioning, indexed with SWM errors, was not significantly related to psychotic symptoms [odds ratio (OR) 1.36, 95% confidence interval (CI) 0.85-2.17, p = 0.204). Poor hot executive functioning, indexed as decision-making score, was associated with psychotic symptoms after adjustment for age, sex and familial clustering (OR 2.37, 95% CI 1.25-4.50, p = 0.008). The association between worse hot executive functions and psychotic symptoms remained significant in sensitivity analyses controlling for general cognitive ability and cold executive functions.

CONCLUSIONS

Impaired hot executive functions may be an indicator of risk and a target for pre-emptive early interventions in youth.

Abnormal prefrontal and parietal activity linked to deficient active binding in working memory in schizophrenia

Working memory deficits have been widely reported in schizophrenia, and may result from inefficient binding processes. These processes, and their neural correlates, remain understudied in schizophrenia. Thus, we designed an FMRI study aimed at investigating the neural correlates of both passive and active binding in working memory in schizophrenia. Nineteen patients with schizophrenia and 23 matched controls were recruited to perform a working memory binding task, in which they were instructed to memorize three letters and three spatial locations. In the passive binding condition, letters and spatial locations were directly presented as bound. Conversely, in the active binding condition, words and spatial locations were presented as separated, and participants were instructed to intentionally create associations between them. Patients exhibited a similar performance to the controls for the passive binding condition, but a significantly lower performance for the active binding. FMRI analyses revealed that this active binding deficit was related to aberrant activity in the posterior parietal cortex and the ventrolateral prefrontal cortex. This study provides initial evidence of a specific deficit for actively binding information in schizophrenia, which is linked to dysfunctions in the neural networks underlying attention, manipulation of information, and encoding strategies. Together, our results suggest that all these dysfunctions may be targets for neuromodulation interventions known to improve cognitive deficits in schizophrenia.

A population-based study of premorbid scholastic achievement among patients with psychiatric disorders

Population-based studies of premorbid cognitive functioning in schizophrenia have found verbal deficits and low IQ scores. It remains unclear, however, whether premorbid deficits are specific to schizophrenia, compared with other psychiatric disorders. Moreover, studies using school-based measures are few and their results inconsistent. This study assesses the eighth-grade (ages 13-14; n=11, 418) scholastic performance of adults with psychiatric disorders (n=194, 1.7, particularly with schizophrenia (n=86, 0.8%), comparing the results with those of their normative peers. The researchers examined report cards of eighth-graders at state secular schools in Jerusalem over a ten-year period (1978-1988), applying ANOVA and logistic regression models to evaluate associations between school performance and subsequent psychiatric hospitalization. The findings indicated that participants hospitalized with varied psychiatric disorders had lower grades in mathematics, gym, handcraft and academic core subjects, with significantly lower overall scores. Amended logistic regression models indicate that reduced performance (in mathematics, gym, handcraft and overall scores) was correlated with an increasing likelihood of hospitalization for the psychiatric disorders group and the subgroup with schizophrenia-related ailments. These results imply that eighth-grade school performance in core subjects is poorer among persons later hospitalized with psychiatric disorders than that of their classmates.

Neurocognitive Impairments in Unaffected First-degree Relatives of Schizophrenia

BACKGROUND

Neurocognitive impairments of attention and executive functioning are trait abnormalities in schizophrenia, and these are considered to be endophenotypes. These deficits have been convincingly linked to prefrontal cortical functioning. In this study, we examined the cognitive performance in the domains of attention and executive functioning among first-degree relatives of Indian people with schizophrenia (high-risk [HR] patients) compared to healthy controls (HC).

MATERIALS AND METHODS

Siblings of patients with DSM-IV schizophrenia, HR patients (n = 17), were compared with HC (n = 30) (matched as a group for age, sex, years of education, and handedness) using the following neurocognitive tests for attention and executive function - digit span test (DST), trail making test, letter-number sequencing (LNS), and spatial span test.

RESULTS

HR patients had significantly deficient performance in attention and executive function tasks (DST-forward [P < 0.001], DST-backward [P < 0.001], spatial span-forward [P < 0.001], spatial span-backward [P < 0.001], and LNS [P < 0.001]).

CONCLUSIONS

This study replicates the findings that neurocognitive deficits involving executive function task performance, attention, and working memory, which are considered as principal features in patients with schizophrenia, are also significantly present in the first-degree relatives of patients. Thus, these neurocognitive parameters can be considered as potential endophenotypes in schizophrenia.

Educational achievement in psychiatric patients and their siblings: a register-based study in 30 000 individuals in The Netherlands

BACKGROUND

Poor educational achievement is associated with a range of psychiatric disorders. Several studies suggest that this underperformance is due to cognitive deficits that commence before disease onset and reflect a genetic risk for this disorder. However, the specificity and the familial contribution of this cognitive deficit are not clear. We analysed lifetime educational achievement of psychiatric patients diagnosed with schizophrenia, bipolar or depressive disorder and their unaffected siblings.

METHOD

In a register-based case-control study, 1561 patients with schizophrenia, 813 patients with bipolar disorder, 8112 patients with depression, and their siblings were each matched with eight population controls. Patients, siblings and controls were compared on the highest educational stream they completed.

RESULTS

Lower educational achievement was present in schizophrenia patients from primary school onwards [completing primary school: odds ratio (OR) 0.69; completing secondary school: OR 0.69; completing academic education: OR 0.46], compared to patients with bipolar disorder or depression. Siblings of schizophrenia, bipolar or depressed patients showed no underachievement at primary or secondary school, but siblings of schizophrenia patients as well as siblings of depressed patients were less successful in their educational achievement after secondary school (completing academic education, schizophrenia siblings: OR 0.90; depressive disorder siblings: OR 0.91).

CONCLUSIONS

Educational underachievement from primary school onwards is specifically related to schizophrenia and not to bipolar disorder or depression. Moreover, it appears to be a harbinger of the illness, since it is not found in their siblings. These results add to evidence that early cognitive deficits are a distinct feature of the schizophrenia phenotype.

Psychotic experiences and suicide attempt risk in common mental disorders and borderline personality disorder

OBJECTIVE

Recent research has demonstrated a strong relationship between psychotic experiences and suicidal behaviour. No research to date, however, has investigated the role of borderline personality disorder (BPD) in this relationship, despite the fact that BPD is highly comorbid with common mental disorders and is associated with both recurrent suicidal behaviour and psychotic experiences. This paper examined the relationship between psychotic experiences and suicide attempts, including interrelationships with BPD and common mental disorders.

METHOD

We used the 2007 Adult Psychiatric Morbidity Study, a stratified, multistage probability sample of households in England, which recruited a nationally representative sample aged 16 years and older. Participants were assessed for common mental disorders, BPD (clinical and subclinical), suicidal behaviour, and psychotic experiences.

RESULTS

Approximately 4% of the total sample (n = 323) reported psychotic experiences. Psychotic experiences were associated with increased odds of suicide attempts in individuals with BPD (OR = 2.23, 95% CI = 1.03-4.85), individuals with a common mental disorder (OR = 2.47, 95% CI = 1.37-4.43), individuals without a common mental disorder (OR = 3.99, 95% CI = 2.47-6.43), and individuals with neither a common mental disorder nor BPD (OR = 3.20, 95% CI = 1.71-5.98).

CONCLUSION

Psychotic experiences are associated with high odds of suicidal behaviour in individuals with and without psychopathology. This relationship is not explained by clinical or subclinical BPD.

Genetic Association of TCF4 and AKT1 Gene Variants with the Age at Onset of Schizophrenia

BACKGROUND

Age at onset (AAO) is a known prognostic indicator for schizophrenia and is hypothesized to correlate with cognition and symptom severity. TCF4 and AKT1 are schizophrenia risk genes involved in cognitive functions. The current study examined the interactive effects of TCF4 and AKT1 variants with gender, family history of psychiatric disorders and ethnicity on the AAO of schizophrenia.

METHODS

This study consisted of 322 patients with schizophrenia meeting the DSM-IV criteria. Six single nucleotide polymorphisms (SNPs) of TCF4 (rs12966547, rs8766, rs2958182, rs9960767, rs10401120 and rs17512836) and seven AKT1 SNPs (rs2498804, rs3803304, rs2494732, rs3730358, rs1130214, rs2498784 and rs3803300) were genotyped using the TaqMan® SNP genotyping-based assays method. The relationship of AAO with each variant was investigated using analyses of covariance.

RESULTS

Among the TCF4 variants, rs12966547 (p = 0.024) and rs8766 (p = 0.021) were significantly associated with earlier AAO. We found a lower average AAO in patients with the AA genotype of rs12966547, while the CT genotype of rs8766 was demonstrated to have a protective effect on AAO. For rs8766, there was significant gene × gender interaction (p = 0.012) in influencing AAO. However, these results were not significant after false discovery rate correction. Significant gene × ethnicity interactions were observed to influence AAO (p < 0.05). The Kaplan-Meier curve of the minor AA genotype of rs12966547 displayed a significant trend (p = 0.008) for onset after 19 years of age. Similarly, the minor CC genotype of rs8766 showed a significantly (p = 0.034) lower AAO compared to the TT genotype.

CONCLUSION

Our analyses suggest that individual risk genotypes may influence the risk of schizophrenia in an age-specific manner.

Academic Performance in Children of Mothers With Schizophrenia and Other Severe Mental Illness, and Risk for Subsequent Development of Psychosis: A Population-Based Study

OBJECTIVE

We examined the academic performance at age 12 years of children of mothers diagnosed with schizophrenia or other severe mental illness using a large whole-population birth cohort born in Western Australia. We investigated the association between academic performance and the subsequent development of psychotic illness.

METHOD

The sample comprised 3169 children of mothers with severe mental illness (schizophrenia, bipolar disorder, unipolar major depression, delusional disorder or other psychoses; ICD-9 codes 295-298), and 88 353 children of comparison mothers without known psychiatric morbidity. Academic performance of children was indexed on a mandatory state-wide test of reading, spelling, writing and numeracy.

RESULTS

A larger proportion of children (43.1%) of mothers with severe mental illness performed below the acceptable standard than the reference group (30.3%; children of mothers with no known severe mental illness). After adjusting for covariates, children of mothers with any severe mental illness were more likely than the reference group to perform below-benchmark on all domains except reading. For all children, poor spelling was associated with the later development of psychosis, but particularly for those at familial risk for severe mental illness (hazard ratio [HR] = 1.81; 95% CI for HR = 1.21, 2.72).

CONCLUSIONS

Children of mothers with a severe mental illness are at increased risk for sub-standard academic achievement at age 12 years, placing these children at disadvantage for the transition to secondary school. For children with familial risk for severe mental illness, very poor spelling skills at age 12 years may be an indicator of risk for later psychotic disorder.

Abnormal interactions of verbal- and spatial-memory networks in young people at familial high-risk for schizophrenia

BACKGROUND

Working memory impairment (especially in verbal and spatial domains) is the core neurocognitive impairment in schizophrenia and the familial high-risk (FHR) population. Inconsistent results have been reported in clinical and neuroimaging studies examining the verbal- and spatial-memory deficits in the FHR subjects, due to sample differences and lack of understanding on interactions of the brain regions for processing verbal- and spatial-working memory.

METHODS

Functional MRI data acquired during a verbal- vs. spatial-memory task were included from 51 young adults [26 FHR and 25 controls]. Group comparisons were conducted in brain activation patterns responding to 1) verbal-memory condition (A), 2) spatial-memory condition (B), 3) verbal higher than spatial (A-B), 4) spatial higher than verbal (B-A), 5) conjunction of brain regions that were activated during both A and B (A∧B). Group difference of the laterality index (LI) in inferior frontal lobe for condition A was also assessed.

RESULTS

Compared to controls, the FHR group exhibited significantly decreased brain activity in left inferior frontal during A, and significantly stronger involvement of ACC, PCC, paracentral gyrus for the contrast of A-B. The LI showed a trend of reduced left-higher-than-right pattern for verbal-memory processing in the HR group.

CONCLUSIONS

Our findings suggest that in the entire functional brain network for working-memory processing, verbal information processing associated brain pathways are significantly altered in people at familial high risk for developing schizophrenia. Future studies will need to examine whether these alterations may indicate vulnerability for predicting the onset of Schizophrenia.

Consensus paper of the WFSBP Task Force on Biological Markers: Criteria for biomarkers and endophenotypes of schizophrenia part II: Cognition, neuroimaging and genetics

OBJECTIVES

Schizophrenia is a group of severe psychiatric disorders with high heritability but only low odds ratios of risk genes. Despite progress in the identification of pathophysiological processes, valid biomarkers of the disease are still lacking.

METHODS

This comprehensive review summarises recent efforts to identify genetic underpinnings, clinical and cognitive endophenotypes and symptom dimensions of schizophrenia and presents findings from neuroimaging studies with structural, functional and spectroscopy magnetic resonance imaging and positron emission tomography. The potential of findings to be biomarkers of schizophrenia is discussed.

RESULTS

Recent findings have not resulted in clear biomarkers for schizophrenia. However, we identified several biomarkers that are potential candidates for future research. Among them, copy number variations and links between genetic polymorphisms derived from genome-wide analysis studies, clinical or cognitive phenotypes, multimodal neuroimaging findings including positron emission tomography and magnetic resonance imaging, and the application of multivariate pattern analyses are promising.

CONCLUSIONS

Future studies should address the effects of treatment and stage of the disease more precisely and apply combinations of biomarker candidates. Although biomarkers for schizophrenia await validation, knowledge on candidate genomic and neuroimaging biomarkers is growing rapidly and research on this topic has the potential to identify psychiatric endophenotypes and in the future increase insight on individual treatment response in schizophrenia.

Cognitive functioning in individuals at ultra-high risk for psychosis, first-degree relatives of patients with psychosis and patients with first-episode schizophrenia

OBJECTIVE

The aim of the present study was to investigate and compare cognitive functioning of first-degree relatives of people with schizophrenia who were also at ultra-high risk (UHR) for psychosis with patients with first-episode (FE) schizophrenia, first degree relatives of patients not fulfilling UHR criteria (FDR), and healthy control (HC) subjects.

METHOD

Forty subjects in each group were included, underwent a face-to-face interview and completed a neurocognitive test battery, including the Trail Making Test-A (TMT-A, psychomotor functions), Stroop Color Word Test (attention), Digit Symbol Coding Test (DST, processing speed and working memory) and Hopkins Verbal Leaning Test-Revised (HVLT-R, verbal memory).

RESULTS

Functioning in all the cognitive test domains displayed a gradual decrease from the HC, FDR, UHR to FE groups. After controlling for covariates, there were still significant differences in TMT-A (F(7160)=35.4, P<0.001), DST (F(7160)=38.9, P<0.001), Stroop Color Word Test (F(7160)=35.0, P<0.001), Stroop Word Test (F(7160)=36.2, P<0.001), Stroop Color Test (F(7160)=40.9, P<0.001) and HVLT-R (F(7160)=62.5, P<0.001) between the four groups, indicating that the cognitive functioning in the UHR group was intermediate between the FE and FDR groups, while the FDR group had poorer performance than the HC group, and the FE group had the poorest cognitive functioning across all four examined domains.

CONCLUSION

The results indicate that impairments in processing speed, attention, working memory and verbal memory exist in both UHR and FDR subjects. In order to clarify the associations between cognitive functioning and UHR and schizophrenia, longitudinal studies are warranted.

Psychotic Experiences and Working Memory: A Population-Based Study Using Signal-Detection Analysis

Psychotic Experiences (PEs) during adolescence index increased risk for psychotic disorders and schizophrenia in adult life. Working memory (WM) deficits are a core feature of these disorders. Our objective was to examine the relationship between PEs and WM in a general population sample of young people in a case control study. 4744 individuals of age 17–18 from Bristol and surrounding areas (UK) were analyzed in a cross-sectional study nested within the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort study. The dependent variable was PEs, assessed using the semi-structured Psychosis-Like Symptom Interview (PLIKSi). The independent variable was performance on a computerized numerical n-back working memory task. Signal-Detection Theory indices, including standardized hits rate, false alarms rate, discriminability index (d’) and response bias (c) from 2-Back and 3-Back tasks were calculated. 3576 and 3527 individuals had complete data for 2-Back and 3-Back respectively. Suspected/definite PEs prevalence was 7.9% (N = 374). Strongest evidence of association was seen between PEs and false alarms on the 2-Back, (odds ratio (OR) = 1.17 [95% confidence intervals (CI) 1.01, 1.35]) and 3-back (OR = 1.35 [1.18, 1.54]) and with c (OR = 1.59 [1.09, 2.34]), and lower d’ (OR = 0.76 [0.65, 0.89]), on the 3-Back. Adjustment for several potential confounders, including general IQ, drug exposure and different psycho-social factors, and subsequent multiple imputation of missing data did not materially alter the results. WM is impaired in young people with PEs in the general population. False alarms, rather than poor accuracy, are more closely related to PEs. Such impairment is consistent with different neuropsychological models of psychosis focusing on signal-to-noise discrimination, probabilistic reasoning and impaired reality monitoring as a basis of psychotic symptoms.

Toward earlier identification and preventative intervention in schizophrenia: evidence from the London Child Health and Development Study

PURPOSE

The London Child Health and Development Study (CHADS) is a prospective, longitudinal investigation of children, sampled from the general community aged 9-11 years and assessed biennially, who present premorbid risk markers for schizophrenia. The study aims to characterise developmental trajectories of psychological, cognitive, and biological functioning in at-risk children and identify potential targets for early preventative intervention. This review summarises CHADS findings, discusses these in the context of recent theory regarding aetiology and prevention of schizophrenia, and highlights challenges to be addressed with future research.

METHODS

We review (1) epidemiological information on the prevalence and correlates of developmental antecedents of schizophrenia in the general child population, (2) evidence of psychosocial, cognitive, and biological dysfunctions in at-risk children presenting multiple antecedents of schizophrenia and at-risk children with a family history of schizophrenia, and (3) related findings from an associated sample of help-seeking children receiving intervention.

RESULTS

Community-based screening of 9-11-year olds identified ~9 % with a triad of antecedents of schizophrenia [including psychotic-like experiences (PLEs)] who are putatively at-risk of psychosis; these children reported greater exposure and responsivity to stressors, impairments in general intelligence and specific cognitive functions, brain structure and function abnormalities, and neuromotor dysfunction. Preliminary evidence suggests distressing PLEs are a viable target for cognitive-behavioural intervention in at-risk children.

CONCLUSIONS

Intervention in early, premorbid phases of illness might alleviate current difficulties and avert future schizophrenia using benign treatments. The CHADS programme has identified several markers that may index early pathophysiology and constitute potential targets for preventative intervention.

The CCC2000 Birth Cohort Study of Register-Based Family History of Mental Disorders and Psychotic Experiences in Offspring

Psychotic experiences (PE) in individuals of the general population are hypothesized to mark the early expression of the pathology underlying psychosis. This notion of PE as an intermediate phenotype is based on the premise that PE share genetic liability with psychosis. We examined whether PE in childhood was predicted by a family history of mental disorder with psychosis rather than a family history of nonpsychotic mental disorder and whether this association differed by severity of PE. The study examined data on 1632 children from a general population birth cohort assessed at age 11-12 years by use of a semistructured interview covering 22 psychotic symptoms. The Danish national registers were linked to describe the complete family history of hospital-based psychiatric diagnoses. Uni- and multivariable logistic regressions were used to test whether a family history of any mental disorder with psychosis, or of nonpsychotic mental disorder, vs no diagnoses was associated with increased risk of PE in offspring (hierarchical exposure variable). The occurrence of PE in offspring was significantly associated with a history of psychosis among the first-degree relatives (adjusted relative risk [RR] = 3.29, 95% CI: 1.82-5.93). The risk increased for combined hallucinations and delusions (adjusted RR = 5.90, 95% CI: 2.64-13.16). A history of nonpsychotic mental disorders in first-degree relatives did not contribute to the risk of PE in offspring nor did any mental disorder among second-degree relatives. Our findings support the notion of PE as a vulnerability marker of transdiagnostic psychosis. The effect of psychosis in first-degree relatives may operate through shared genetic and environmental factors.

IQ and schizophrenia in a Swedish national sample: their causal relationship and the interaction of IQ with genetic risk

OBJECTIVE

The authors sought to clarify the relationship between IQ and subsequent risk for schizophrenia.

METHOD

IQ was assessed at ages 18-20 in 1,204,983 Swedish males born between 1951 and 1975. Schizophrenia was assessed by hospital diagnosis through 2010. Cox proportional hazards models were used to investigate future risk for schizophrenia in individuals as a function of their IQ score, and then stratified models using pairs of relatives were used to adjust for familial cluster. Finally, regression models were used to examine the interaction between IQ and genetic liability on risk for schizophrenia.

RESULTS

IQ had a monotonic relationship with schizophrenia risk across the IQ range, with a mean increase in risk of 3.8% per 1-point decrease in IQ; this association was stronger in the lower than the higher IQ range. Co-relative control analyses showed a similar association between IQ and schizophrenia in the general population and in cousin, half-sibling, and full-sibling pairs. A robust interaction was seen between genetic liability to schizophrenia and IQ in predicting schizophrenia risk. Genetic susceptibility for schizophrenia had a much stronger impact on risk of illness for those with low than high intelligence. The IQ-genetic liability interaction arose largely from IQ differences between close relatives.

CONCLUSIONS

IQ assessed in late adolescence is a robust risk factor for subsequent onset of schizophrenia. This association is not the result of a declining IQ associated with insidious onset. In this large, representative sample, we found no evidence for a link between genius and schizophrenia. Co-relative control analyses showed that the association between lower IQ and schizophrenia is not the result of shared familial risk factors and may be causal. The strongest effect was seen with IQ differences within families. High intelligence substantially attenuates the impact of genetic liability on the risk for schizophrenia.

Adolescent self-control predicts midlife hallucinatory experiences: 40-year follow-up of a national birth cohort

BACKGROUND

Associations between self-control in adolescence and adult mental health are unclear in the general population; to our knowledge, no study has investigated self-control in relation to psychotic-like symptoms.

AIMS

To investigate the relationship between adolescent self-control and the midlife mental health outcomes of anxiety and depression symptoms and psychotic-like experiences (PLEs), controlling for the effect of adolescent conduct and emotional problems and for parental occupational social class and childhood cognition.

METHODS

A population-based sample, the MRC National Survey of Health and Development (the British 1946 birth cohort) was contacted 23 times between ages 6 weeks and 53 years. Teachers completed rating scales to assess emotional adjustment and behaviors, from which factors measuring self-control, behavioral, and emotional problems were extracted. At age 53 years, PLEs were self-reported by 2918 participants using 4 items from the Psychosis Screening Questionnaire; symptoms of anxiety and depression were assessed using the scaled version of the General Health Questionnaire (GHQ-28).

RESULTS

After adjustment for the above covariates, poor adolescent self-control was associated with the presence of PLEs in adulthood, specifically hallucinatory experiences at age 53 years, even after adjustment for GHQ-28 scores.

CONCLUSIONS

Lower self-control in adolescence is a risk factor for hallucinatory experiences in adulthood.

Cortisol awakening response and diurnal cortisol among children at elevated risk for schizophrenia: relationship to psychosocial stress and cognition

Abnormal hypothalamic-pituitary-adrenal (HPA) axis function, as indexed by elevated diurnal cortisol levels and/or a blunted cortisol awakening response (CAR), has been observed among patients with first episode psychosis and associated with neurocognitive deficits in this population. However, the extent to which these features precede illness onset is unclear. The current study aimed to determine whether children who are at putatively elevated risk for psychosis because they present multiple antecedents of schizophrenia (ASz), and high-risk children with a family history of illness (FHx), are characterized by abnormal cortisol levels when compared with their typically developing (TD) peers. A further aim was to investigate the extent to which cortisol levels are associated with psychosocial stress and neurocognitive function. Thirty-three ASz children, 22 FHx children, and 40 TD children were identified at age 9-12 years using a novel community-based screening procedure or as relatives of individuals with schizophrenia. All participants were antipsychotic-naive and not currently seeking treatment for their symptoms. At age 11-14 years, participants provided salivary cortisol samples and completed psychosocial stress measures and tests of memory and executive function. Results indicated that FHx children, but not ASz children, were characterized by a blunted CAR relative to their TD peers (effect size=-0.73, p=0.01) that was not explained by psychosocial stress exposure or by distress relating to these experiences. Neither FHx nor ASz children were characterized by elevated diurnal cortisol. Among both FHx and ASz children, more pronounced HPA axis function abnormalities (i.e., higher diurnal cortisol levels and greater blunting of the CAR) were associated with poorer performance on tests of verbal memory and executive function. These findings support the notion that at least some HPA axis abnormalities described in psychosis precede illness onset, rather than being a subsequent epiphenomenon. We speculate that the blunted CAR may constitute an early (potentially genetically mediated) marker of psychosis vulnerability, whilst elevated diurnal cortisol levels may emerge only proximally to disease onset.