Neurocognitive impairments in schizophrenia: a piece of the epigenetic puzzle

Predicting new onset thought disorder in early adolescence with optimized deep learning implicates environmental-putamen interactions

Background

Thought disorder (TD) is a sensitive and specific marker of risk for schizophrenia onset. Specifying factors that predict TD onset in adolescence is important to early identification of youth at risk. However, there is a paucity of studies prospectively predicting TD onset in unstratified youth populations.

Study Design

We used deep learning optimized with artificial intelligence (AI) to analyze 5,777 multimodal features obtained at 9-10 years from youth and their parents in the ABCD study, including 5,014 neural metrics, to prospectively predict new onset TD cases at 11-12 years. The design was replicated for all prevailing TD cases at 11-12 years.

Study Results

Optimizing performance with AI, we were able to achieve 92% accuracy and F1 and 0.96 AUROC in prospectively predicting the onset of TD in early adolescence. Structural differences in the left putamen, sleep disturbances and the level of parental externalizing behaviors were specific predictors of new onset TD at 11-12 yrs, interacting with low youth prosociality, the total parental behavioral problems and parent-child conflict and whether the youth had already come to clinical attention. More important predictors showed greater inter-individual variability.

Conclusions

This study provides robust person-level, multivariable signatures of early adolescent TD which suggest that structural differences in the left putamen in late childhood are a candidate biomarker that interacts with psychosocial stressors to increase risk for TD onset. Our work also suggests that interventions to promote improved sleep and lessen parent-child psychosocial stressors are worthy of further exploration to modulate risk for TD onset.

Motor function in early onset schizophrenia-A 2-year follow-up study

AIM

Motor symptoms primarily assessed by clinical rating are documented across the schizophrenia spectrum, but no studies have examined the longitudinal course of these symptoms in adolescents using tests that control for the natural maturational process. The aim is therefore to compare fine and gross motor function using age-adjusted tests in adolescents with schizophrenia and controls across a 2-year period, and examine if clinical correlates contribute to changes in motor function in adolescents with schizophrenia.

METHOD

Motor function assessed by two age-adjusted tests was compared in 25 adolescents with schizophrenia and age- and sex-matched controls over a 2-year period using t-tests, Cohen's D and χ2 tests. Linear mixed models with a random intercept at patient level were used to assess changes between baseline and follow-up. The latter approach was adopted to assess the association between changes and potential predictors as age, sex, complications during labour/delivery, childhood motor function, symptoms severity, executive function and antipsychotics.

RESULT

All measures of motor function but one significantly differentiated adolescents with schizophrenia from controls with large effect sizes at 2-year follow-up. The overall scores did not change during follow-up, whereas two resembling motor areas of the tests significantly improved in adolescents with schizophrenia. The severity of schizophrenia, sex and IQ revealed association with the changes.

CONCLUSION

The finding of both stability and improvements from diagnosis to follow-up in adolescents with schizophrenia and the differences between adolescents with and without schizophrenia argue in favour of the neurodevelopment hypothesis and highlights the need for assessing motor function.

Schizophrenia and risk of dementia: a meta-analysis study

BACKGROUND

Evidence suggests that schizophrenia may be associated with an increased risk of dementia, but results from prior studies have been inconsistent. This study aimed to estimate the relationship between schizophrenia and incident dementia using a quantitative meta-analysis.

METHODS

Several databases were used to gather relevant information, including PubMed, Embase, and Web of Science, with the publication date of articles limited up to December 23, 2017. All studies reported a multivariate-adjusted estimate, represented as relative risk (RR) with 95% confidence intervals (CIs), for the association between schizophrenia and risk of dementia incidence. Pooled RRs were calculated using a random-effects model.

RESULTS

Six studies met our inclusion criteria for this meta-analysis, which included 206,694 cases of dementia and 5,063,316 participants. All individuals were without dementia at baseline. Overall, the quantitative meta-analysis suggested that subjects with schizophrenia were associated with a significantly greater risk of dementia incidence (RR 2.29; 95% CI 1.35-3.88) than those without.

CONCLUSION

The results of this meta-analysis indicate that individuals with schizophrenia may have an increased risk for the development of dementia. Future studies should explore whether schizophrenia is a modifiable risk factor for dementia.

Formal thought disorder in people at ultra-high risk of psychosis

BACKGROUND

Formal thought disorder is a cardinal feature of psychosis. However, the extent to which formal thought disorder is evident in ultra-high-risk individuals and whether it is linked to the progression to psychosis remains unclear.

AIMS

Examine the severity of formal thought disorder in ultra-high-risk participants and its association with future psychosis.

METHOD

The Thought and Language Index (TLI) was used to assess 24 ultra-high-risk participants, 16 people with first-episode psychosis and 13 healthy controls. Ultra-high-risk individuals were followed up for a mean duration of 7 years (s.d.=1.5) to determine the relationship between formal thought disorder at baseline and transition to psychosis.

RESULTS

TLI scores were significantly greater in the ultra-high-risk group compared with the healthy control group (effect size (ES)=1.2), but lower than in people with first-episode psychosis (ES=0.8). Total and negative TLI scores were higher in ultra-high-risk individuals who developed psychosis, but this was not significant. Combining negative TLI scores with attenuated psychotic symptoms and basic symptoms predicted transition to psychosis (P=0.04; ES=1.04).

CONCLUSIONS

TLI is beneficial in evaluating formal thought disorder in ultra-high-risk participants, and complements existing instruments for the evaluation of psychopathology in this group.

DECLARATION OF INTERESTS

None.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.

Higher prevalence of dementia in patients with schizophrenia: A nationwide population-based study

INTRODUCTION

This study investigates the prevalence of dementia in patients with and without schizophrenia, with a particular focus on age-specific and sex-specific differences.

METHODS

We conducted a population-based study using the National Health Insurance claims database from 2010 to 2013. Using a 10:1 matching ratio, 248,919 patients without schizophrenia and 26,591 patients with schizophrenia were identified based on the ICD-10 code. Patients with dementia were extracted by diagnosis or use of anti-dementia drugs. Conditional logistic regression analyses were performed to evaluate the association between schizophrenia and dementia.

RESULTS

The prevalence of dementia was significantly higher in schizophrenia patients compared with that in matched non-schizophrenia patients (9.9% versus 2.2%, P < 0.0001). After adjusting for Charlson comorbidity index and underlying comorbidities, conditional logistic regression showed that schizophrenia was associated with dementia (adjusted odds ratio [AOR], 4.7; 95% confidence interval [CI], 4.4-5.1). When stratified by sex, the AOR was 5.6 (95% CI, 5.0-6.2) among women and 4.0 (95% CI, 3.6-4.5) among men. Moreover, the association between dementia and schizophrenia was strong in elderly patients. The AOR of dementia prevalence was 6.6 (95% CI, 6.1-7.2) in patients aged ≥65 years and 3.4 (95% CI, 3.0-3.8) in patients aged <65 years.

DISCUSSION

Schizophrenia patients were more likely to have dementia compared with non-schizophrenia patients. This association seems greater in higher prevalence groups such as women and patients aged ≥65 years. Further investigation on the mechanism is required.

Evidence for corticostriatal dysfunction during cognitive skill learning in adolescent siblings of patients with childhood-onset schizophrenia

Patients with schizophrenia perform poorly on cognitive skill learning tasks. This study is the first to investigate the neural basis of impairment in cognitive skill learning in first-degree adolescent relatives of patients with schizophrenia. We used functional magnetic resonance imaging to compare activation in 16 adolescent siblings of patients with childhood-onset schizophrenia (COS) and 45 adolescent controls to determine whether impaired cognitive skill learning in individuals with genetic risk for schizophrenia was associated with specific patterns of neural activation. The siblings of patients with COS were severely impaired on the Weather Prediction Task (WPT) and showed a relative deactivation in frontal regions and in the striatum after extensive training on the WPT compared with controls. These differences were not accounted for by performance differences in the 2 groups. The results suggest that corticostriatal dysfunction may be part of the liability for schizophrenia.

Impaired automatization of a cognitive skill in first-degree relatives of patients with schizophrenia

We studied healthy, first-degree relatives of patients with schizophrenia to test the hypothesis that deficits in cognitive skill learning are associated with genetic liability to schizophrenia. Using the Weather Prediction Task (WPT), 23 healthy controls and 10 adult first-degree Relatives Of Schizophrenia (ROS) patients were examined to determine the extent to which cognitive skill learning was automated using a dual-task paradigm to detect subtle impairments in skill learning. Automatization of a skill is the ability to execute a task without the demand for executive control and effortful behavior and is a skill in which schizophrenia patients possess a deficit. ROS patients did not differ from healthy controls in accuracy or reaction time on the WPT either during early or late training on the single-task trials. In contrast, the healthy control and ROS groups were differentially affected during the dual-task trials. Our results demonstrate that the ROS group did not automate the task as well as controls and continued to rely on controlled processing even after extensive practice. This suggests that adult ROS patients may engage in compensatory strategies to achieve normal levels of performance and support the hypothesis that impaired cognitive skill learning is associated with genetic risk for schizophrenia.

Psychosis in children: diagnosis and treatment

The diagnosis of childhood psychosis raises a host of unresolved problems, despite the Diagnostic and Statistical Manual Of Mental Disorders, 4th edition, Text Revision (DSM-IV-TR) giving identical symptoms and definitions for children, adolescents, and adults. The fantasy lives of children, and issues of developing language and cognition (including retardation), all impair diagnostic accuracy, particularly when differentiating between childhood-onset schizophrenia (COS) (≤12 years), bipolar affective disorder, major depressive disorder, and even obsessive-compulsive disorder and attention-deficit/hyperactivity disorder: the catch-all classification, psychosis not otherwise specified (PNOS), is always available for conundra that prove unsolvable. Typical if nonpathognomonic features include neurocognitive difficulties. Multiple screening instruments and specialized versions of semistructured diagnostic interviews are available. Although smooth-pursuit eye-tracking movements may prove a genetic marker for COS, etiologies are likely to be oligogenetic rather than related to a single gene. No specific biological markers or neuroimages have been identified. As such, psychoses may be indicative of a more general pattern of brain dysfunction. Drug treatments are largely based on the adult literature because of a dearth of controlled data below age 18. There are still no rigorous studies of psychosocial treatments and psychotherapy specific to childhood psychosis.

Is there evidence for late cognitive decline in chronic schizophrenia?

Schizophrenia (SZP) has been historically referred to as "dementia praecox" because of the recognition that its onset is associated with deficits in memory, attention and visuospatial orientation. We wondered whether there is evidence for additional cognitive decline late in the course of chronic SZP. This review examined the evidence (1) for cognitive decline late in the course of chronic SZP, (2) for how often the late cognitive decline occurs, and (3) whether the cognitive decline in late-life SZP is related to pathophysiology of SZP versus the superimposition of another type of dementia. A PUBMED search was performed combining the MESH terms schizophrenia and dementia, cognitive decline, cognitive impairment and cognitive deficits. A manual search of article bibliographies was also performed. We included longitudinal clinical studies employing standard tests of cognition. Cross-sectional studies and those that did not test cognition through standard cognitive tests were excluded. The initial search produced 3898 studies. Employing selection criteria yielded twenty-three studies. Our data extraction tool included the number of patients in the study, whether a control group was present, the age of patients at baseline and follow-up, the study setting (inpatients versus outpatients), the cognitive tests employed, study duration, and results. Only three longitudinal studies tested for dementia using Diagnostic and statistical manual of mental disorder (DSM) or International classification of disease (ICD) criteria and compared them to controls: two studies demonstrated an increase in the prevalence of dementia and one did not. Twenty longitudinal studies tested for one or more cognitive domains without employing standard criteria for dementia: twelve studies demonstrated a heterogeneous pattern of cognitive decline and eight did not. Studies generally did not control for known risk factors for cognitive impairment such as education, vascular risk factors, apolipoprotein (ApoE) genotype and family history. The evidence for late cognitive decline in SZP is mixed, but, slightly more studies suggest that it occurs. If it occurs, it is unclear whether it is related to SZP or other risks for cognitive impairment. Hence, prospective, longitudinal, controlled studies are needed to confirm that there is progressive cognitive decline in chronic SZP which occurs independent of other risk factors for cognitive impairment.

Cognitive function in early onset schizophrenia: a selective review

Schizophrenia is widely regarded as the clinical outcome of aberrant neurodevelopment caused by a combination of genetic and non-genetic factors. Early Onset Schizophrenia (EOS) manifests in childhood or adolescence and represents a more severe variant of the Adult Onset form of the disorder (AOS). EOS offers a unique opportunity of exploring the impact of disease related mechanisms on the developmental trajectory of cognitive function. The present review focused on the domains of general intellectual ability (IQ), attention, executive function and memory. Significant methodological variability was noted across the different studies that examined these aspects of cognition in EOS patients. Despite this, a consistent pattern emergent from the data suggesting that (a) EOS patients compared to healthy children and adolescents show impairments of medium to large effect size in IQ, attention, memory and executive function (b) despite increased clinical severity, the cognitive profile of EOS patients is comparable to that of AOS patients (c) healthy adolescents show age-related improvement in their ability to perform tests of attention, memory and executive function; this is not present in EOS patients thus resulting in increased age-related deviance in patients’ performance. This apparent decline is mostly attributable to patients’ failure to acquire new information and to use more sophisticated cognitive strategies.

Heritability of age of onset of psychosis in schizophrenia

Schizophrenia is a genetically complex illness with heterogeneous clinical presentation, including variable age of onset. In this study, the heritability, or proportion of variation in age of onset of psychotic symptoms due to genetic factors, was estimated using a maximum likelihood method. The subjects were 717 members of families with more than one member affected with schizophrenia from Mexican and Central American populations. Age of onset of psychosis was determined by best-estimate consensus diagnosis based on the Diagnostic Interview for Genetic Studies, Family Interview for Genetic Studies, and each subject's medical records. Mean age of onset was 21.44 years (SD 8.07); 20.55 years for males (SD 6.90), and 22.67 for females (SD 9.34). Variance components were estimated using a polygenic model in the SOLAR software package. The sex of the participant was a significant covariate (P = 0.010) accounting for 0.02 of the total variance in age of onset. The heritability of age of onset of psychosis was 0.33 (SE = 0.09; P = 0.00004). These findings suggest that genetic factors significantly contribute to the age of onset of psychotic symptoms in individuals with schizophrenia and that sex influences this trait as well.

From bench to bedside: translating new research from genetics and neuroimaging into treatment development for early-onset schizophrenia

OBJECTIVE

Children and adolescents with schizophrenia share a similar pattern of phenomenological, genetic and cognitive abnormalities to adults with schizophrenia. However, an early-onset of schizophrenia (EOS) (prior to 18 years of age) is associated with a higher frequency of risk indicators associated with schizophrenia (e.g. developmental delays and familial spectrum disorders) and a worse long-term outcome. This overview examines recent research on the neurobiological alterations, possible causes, developmental trajectory and treatment of EOS and attempts to identify gaps in the field.

METHOD

The authors provide a selective review of major findings from genetics, neuroimaging and treatment studies of pediatric schizophrenia that were presented at a workshop sponsored by the National Institute of Mental Health. These data are synthesized in conjunction with preclinical studies into a model of the pathophysiology of EOS.

RESULTS

EOS is associated with a high frequency of cytogenetic abnormalities (e.g. velocardiofacial syndrome, sex chromosome anomalies) and other rare denovo chromosomal aberrations. Brain imaging research in adolescents with EOS has revealed a progressive loss of cortical grey matter post-onset of psychosis and subtle abnormalities in white matter microstructure. Although EOS patients are more likely to be treatment-refractory than their adult counterparts, there are substantial data that this subgroup is particularly responsive to clozapine.

CONCLUSIONS

Genetic or environmental factors operating during adolescence that reduce frontal capacity might contribute to an EOS in susceptible individuals. Additional longitudinal studies of adolescents with schizophrenia are needed to better understand the relationship between structural changes in fronto-limbic regions, stress responsivity, and cognitive and neurochemical development.

Molecular mechanisms underlying glutamatergic dysfunction in schizophrenia: therapeutic implications

Early models for the etiology of schizophrenia focused on dopamine neurotransmission because of the powerful anti-psychotic action of dopamine antagonists. Nevertheless, recent evidence increasingly supports a primarily glutamatergic dysfunction in this condition, where dopaminergic disbalance is a secondary effect. A current model for the pathophysiology of schizophrenia involves a dysfunctional mechanism by which the NMDA receptor (NMDAR) hypofunction leads to a dysregulation of GABA fast- spiking interneurons, consequently disinhibiting pyramidal glutamatergic output and disturbing the signal-to-noise ratio. This mechanism might explain better than other models some cognitive deficits observed in this disease, as well as the dopaminergic alterations and therapeutic effect of anti-psychotics. Although the modulation of glutamate activity has, in principle, great therapeutic potential, a side effect of NMDAR overactivation is neurotoxicity, which accelerates neuropathological alterations in this illness. We propose that metabotropic glutamate receptors can have a modulatory effect over the NMDAR and regulate excitotoxity mechanisms. Therefore, in our view metabotropic glutamate receptors constitute a highly promising target for future drug treatment in this disease.

The early manifestations of bipolar disorder: a longitudinal prospective study of the offspring of bipolar parents

OBJECTIVE

A major aim of this longitudinal high-risk study is to identify reliable early indicators of emerging bipolar disorder (BD) among offspring from well-characterized parents.

METHODS

High-risk offspring were recruited from families in which one parent had BD diagnosed on the basis of the Schedule for Affective Disorders and Schizophrenia - Lifetime version (SADS-L) interviews and DSM-IV diagnostic criteria and the other parent was well. Bipolar parents were further subdivided on the basis of response or non-response to long-term lithium. A comparison group of offspring was recruited from well parents diagnosed on the basis of either SADS-L interviews or the family history method. All consenting offspring from high-risk and control families were assessed longitudinally with the Schedule for Affective Disorders and Schizophrenia for School-aged Children - Present and Lifetime version (KSADS-PL) interviews and DSM-IV diagnoses were made on a blind consensus review. The offspring were reassessed on average annually, as well as at any time symptoms developed.

RESULTS

Antecedent conditions to BD in both high-risk groups included sleep and anxiety disorders, while attention-deficit hyperactivity disorder and pre-psychotic conditions were antecedents among the offspring of lithium non-responders only. Among those offspring developing BD, the index mood episode was almost always depressive.

CONCLUSIONS

Despite a specific genetic risk, BD began with non-specific psychopathology and/or depressive disorders in a majority of offspring. Therefore, diagnosis based only on cross-sectional assessment of symptoms appears to be insufficient for the accurate early detection of emerging BD. Other parameters such as family history and associated antecedents should be taken into account.

Basic symptoms, temperament and character in adolescent psychiatric disorders

OBJECTIVE

Basic symptoms are early subtle changes in thinking, feeling and perception that are subjectively experienced and precede the onset of a psychotic illness. In adult samples, high basic symptom scores are regarded as specific risk factors for the development of schizophrenia. The aim of this study was to explore the relevance of basic symptoms of psychiatric disorders in adolescent patients with special focus on early detection of psychosis. Furthermore, the association between basic symptoms and personality traits has been investigated.

METHOD

From 89 adolescents, who were consecutive inpatients with different psychiatric disorders in 1995 and 1997, 54 were followed up 4.7 years later. Patients were examined with the Bonn Scale for the Assessment of Basic Symptoms at the time of the first presentation and follow-up. Additionally, personality traits were assessed at follow-up using the Junior Temperament and Character Inventory.

RESULTS

None of the subjects made the transition to schizophrenia, despite high baseline scores of basic symptoms at the initial assessment. Indirect minus symptoms were found to be the most valid predictor of a persisting psychiatric diagnosis. In addition, this specific category was strongly associated with the personality traits harm avoidance and self-directedness.

CONCLUSION

In adolescents, basic symptoms in association with personality traits present as a nonspecific indicator of psychopathology rather than as an indicator of vulnerability to schizophrenia.

Characteristics of early psychosis

There is little research on characteristics related to course and prognosis of early-onset psychosis. The present article aims to advance our knowledge of this disorder for the purpose of proper diagnosis and treatment. It focuses on premorbid and prodromal characteristics, treatment history, symptoms and classifications, and differences between subgroups with affective and schizophrenic psychosis. A chart review was constructed to study a group of 129 subjects (12-18 years) with psychotic symptoms referred to the University Medical Center in Utrecht. The group was characterized by early-but nonspecific-treatment, developmental problems (mostly social), and clear prodromal symptoms. Drug abuse, depressive symptoms, and suicidal behavior were also frequent. Male sex, a relatively long prodromal phase, school problems, and drug abuse were more indicative of the schizophrenic subgroup. Introversion was characteristic for boys with schizophrenia. Classifications, however, were not stable. These findings suggest that early recognition of psychosis can be enhanced in health and youth care facilities. Careful examination of the prodromal phase seems helpful to differentiate between schizophrenic and affective psychosis.

Neurocognitive performance and negative symptoms: are they equal in explaining disability in schizophrenia outpatients?

OBJECTIVE

The aim of this study is to assess if cognitive variables and symptom dimensions can predict disability in a sample of outpatients with schizophrenia.

METHOD

A cross-sectional sample of 113 individuals with a diagnosis of schizophrenia (DSM-IV criteria) was selected from a computerized register of five Community Mental Health Centers. Patients were assessed by two trained psychologists, with a neuropsychological battery comprising measures for verbal memory, attention, operative memory and abstraction and flexibility functions. Symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS); a socio-demographic and clinical questionnaire, comprising the Disability Assessment Scale (DAS), was also completed. Test scores were standardized (t scores) to performance of healthy controls. To assess the relationship between clinical and sociodemographic factors and disability and cognitive functioning Pearson's correlation coefficients were computed. In order to establish the predictive capacity of the cognitive, clinical and symptom variables on disability linear regression models were fitted.

RESULTS

Mean age of patients was 41.6 years and 68% were male. Higher ratings in the negative dimension were associated with more cognitive deficits. Association with the positive dimension was present but less strong. All disability areas, except for disability in occupational functioning, were partially explained by the negative dimension. Disability in family functioning was also partially explained by attention and number of admissions since onset.

CONCLUSION

Negative symptoms are the major source of disability of our sample and are also associated to cognitive functioning. The present findings suggest that further investigation on the mediators between clinical and social outcomes may help to design specific treatments to reduce disability.

Cognitive functioning in patients with schizophrenia and bipolar disorder: a quantitative review

OBJECTIVE

Evidence suggests that cognitive functioning in bipolar disorder may be impaired even in euthymic states, but it is unclear if the pattern of deficits is similar to the deficits found in schizophrenia. The aim of this study was to review quantitatively the studies on cognitive performance in schizophrenia and bipolar disorder.

METHODS

Articles for consideration were identified through a literature search in MEDLINE and PsycLIT in the period between 1985 and October 2004, using the keywords "schizophrenia" combined with "bipolar disorder", or "manic-depress*" or "manic" combined with "cogniti*" or "neuropsycholog*". Thirty-one studies were included that: i) evaluated cognitive performance using standardized and reliable neuropsychological testing procedures; ii) compared adult patients with schizophrenia and with bipolar disorder; iii) reported test scores of both patient groups, or exact p-values, t-values, or F-values; and iv) were published as an original article in a peer-reviewed English language journal.

RESULTS

Meta-analyses of all studies indicated that patients with bipolar disorder generally perform better than patients with schizophrenia, but the distribution of effect sizes showed substantial heterogeneity. Results based on a more homogeneous subset of studies that matched patient groups on clinical and demographic characteristics pointed in the same direction, with effect sizes in the moderate range.

CONCLUSIONS

Patients with bipolar disorder show better cognitive performance than patients with schizophrenia, even when matched for clinical and demographic characteristics.