Neuropsychological functioning in childhood-onset psychosis and attention-deficit/hyperactivity disorder

Neurocognitive dysfunctions in childhood-onset schizophrenia: A systematic review

Objective

To conduct a systematic review of neurocognitive dysfunctions in patients with childhood-onset schizophrenia (COS), a neuropsychiatric disorder that occurs before age 13 and is rarer and more severe than adult-onset schizophrenia.

Method

A search was made in the PubMed database. Sixty-seven studies (out of 543) which analyzed Intellectual Quotient (IQ), attentional, memory and executive functions were selected by two independent researchers. Study's appraisal was done according to the Mixed Methods Appraisal Tool (MMAT). This systematic review was registered on PROSPERO (CRD42024548945).

Result

COS shows neurocognitive dysfunction in IQ with mean scores ranging from one to two standard deviation lower than normative data. Attentional deficits are observed with longer reaction time, more errors of omission and commission and slower processing speed than controls. In addition, working memory and executive functions, such as planification and flexibility are impaired. COS exhibit significantly more neurocognitive deficits than adolescent and adult-onset forms and display deterioration in intellectual functioning between premorbid period and after onset of psychosis.

Conclusion

COS is characterized by major cognitive impairments, both before the onset of the disease and throughout its course. As in adult-onset schizophrenia, generalized cognitive impairment is found without the emergence of a specific profile, providing further support for the continuum hypothesis between early-onset and adult-onset schizophrenia. Collaborative research on a larger scale (including meta-analyses) and using complementary approaches (dimensional and multimodal) is needed to gain a better understanding of the cognitive impact of COS and pave the way for more precise and targeted cognitive remediation.

Memory deficits in children and adolescents with a psychotic disorder: a systematic review and meta-analysis

Early-onset psychosis (EOP) is a severe disorder which takes place before 18 years. It entails diverse clinical and functional implications, and it may lead to critical impairments in neurocognitive functions. Although deficits in memory are well described in adult populations and they appear to be clinically related with psychosis, impairments in memory in EOP show inconsistencies between studies. This study aimed to gain insight into the relationship between EOP and memory impairments, studying the potential contribution of moderators (storage source and memory content) on the observed memory deficits. This systematic review and meta-analysis was conducted following the PRISMA-2020 guidelines. Search was conducted in English and Spanish in five databases. Case-control studies which met all requirements were selected. Overall effect size was calculated under the random-effects model and Z-based tests were used. Heterogeneity was analysed by the I2 statistic. Mixed-effects meta-regression analysis was used to study the influence of methodological quality of studies, mean age, proportion of female participants within sample, mean diagnosis, memory storage type, memory content as moderators on individual effect size variability. As a result, 32 articles were finally selected, pooling data from 2636 participants (49.29% EOP participants). Overall effect size was Hedges' g =  - 1.01, CI95 = [ - 1.35,  - 0.67], p < .01, indicating lower memory performance in the EOP group in comparison to healthy controls. Diagnosis and memory storage were found as significant moderators in the memory performance variance: larger deficits were found in children with psychosis and in working memory tasks.

[ADHD during childhood and subsequent psychotic disorder: A link?]

OBJECTIVES

Attention Deficit with/without Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder with frequent comorbid psychiatric disorders. Several studies have underlined the increased risk of developing a psychotic disorder subsequent to a childhood ADHD. The aim of our review is not only to clarify this association and the related physiopathology but also to understand the consequences for therapeutic management.

METHODS

We processed a narrative review of available literature based on a research of the PubMed database. Articles related to ADHD and psychotic disorder on a genetical, clinical or biological level were selected by one of the authors.

RESULTS

ADHD and psychotic disorders share neonatal, environmental, and genetic risk factors. On a neurobiological level, both disorders are concerned by a dysfunction of the dopaminergic system with an abnormal regulation of dopaminergic neurons' phasic and tonic activity. Our review aims to explain the « dynamic » model of dopaminergic dysfunctions and propose some guidance for pharmacological treatment of ADHD, with or without psychotic disorder. This model offers a better understanding of why methylphenidate is not associated to an increased risk of psychotic disorder and could act as a protective factor. Association between ADHD and psychotic disorders could be explained by some comorbidities such as substance use disorders which are frequently associated with both conditions and could act as mediator in the genesis of psychotic disorders following ADHD during childhood. Our review also focuses on an epidemiological bias that could be found in some studies such as possible diagnostic errors, as some non-specific clinical signs could be found in both late diagnosed ADHD and in "at risk mental state" of psychosis.

CONCLUSION

ADHD and psychotic disorders share common risk factors, neurobiological pathways and clinical symptoms. Perspectives for future studies are proposed considering a dimensional aspect of psychiatric disorders using, for example, Research Domain Criteria and exploring the link between the two conditions.

Clinical and cognitive correlates of childhood attention-deficit/hyperactivity disorder in first-episode psychosis: A controlled study

The relationship between childhood attention-deficit/hyperactivity disorder (c-ADHD) and psychosis has been understudied. Cognitive dysfunction is a core feature of both disorders, but no previous study has investigated whether first-episode psychosis (FEP) with c-ADHD (FEP-ADHD⁺) presents a different cognitive profile than FEP without c-ADHD (FEP-ADHD^-). One hundred and thirty-three FEP outpatients were screened for c-ADHD through a diagnostic interview and underwent a comprehensive clinical and cognitive assessment with the MATRICS Consensus Cognitive Battery (MCCB). Cognitive differences among FEP groups, and a group of 65 healthy controls (HCs) were analysed by multivariate analysis of covariance. Nearly 25% of FEP fulfilled criteria for c-ADHD. Both FEP groups performed worse than HCs in speed processing, executive function and social cognition, but only the FEP-ADHD⁺group was significantly more impaired than the HC group in attention (F = 4.35; p = 0.04). Only the Trail Making Test A (TMT-A) (F = 6.99; p = 0.01) within the domain of processing speed and the Neuropsychological Assessment Battery (NAB) (F = 6.46; p = 0.01) within the domain of executive function reliably differentiated the two clinical groups. The FEP groups did not differ in the severity of psychopathology, but the FEP-ADHD⁺reported fewer years of education than the FEP-ADHD^- and were more likely to use tobacco and cannabis and to require higher doses of antipsychotics to achieve a clinical response. In conclusion, we found a gradient of severity in cognitive performance between groups, with FEP-ADHD⁺ having the greatest cognitive impairment. Our results suggest that FEP-ADHD⁺ represents a subgroup with a worse prognosis than FEP-ADHD^-.

Attention Deficit/Hyperactivity Disorder and risk for non-affective psychotic disorder: The role of ADHD medication and comorbidity, and sibling comparison

Attention Deficit/Hyperactivity Disorder (ADHD) is the most common psychiatric disorder in childhood. It is unclear whether ADHD increases the risk of non-affective psychotic disorder (NAPD). The study included a matched cohort, drawn from all born in Sweden 1987-1991 (n = 548,852). ADHD was defined as ICD diagnosis and/or prescription of ADHD medication. We distinguished between stimulants and non-stimulants, and usage duration (<1 year, 1-2 years and ≥2 years). We calculated odds ratios (OR) with 95% confidence intervals (CI) for NAPD, adjusted for confounders, comorbid autism spectrum disorder (ASD) and substance abuse. ADHD cases were also compared to their unaffected full siblings. We analyzed 18,139 ADHD cases and 72,437 sex and birth year matched controls. NAPD was more common in cases than controls (2.7 and 0.4%, respectively). After adjustment for confounders, ADHD cases had markedly high risk for NAPD (OR: 6.99; 95% CI 6.03-8.10), which attenuated further after adjustment for ASD and substance abuse (OR: 2.57; 95% CI 2.09-3.16). Utilization of ADHD medication increased the risk for NAPD (ORs for change in odds of NAPD for every 5 extra prescriptions of stimulants 1.06 (95% CI 1.02-1.10) and, non-stimulants 1.15 (95% CI 1.01-1.30)). There was no association between usage length of medication and risk for NAPD. The risk was higher in individuals with ADHD than their unaffected siblings (OR: 2.95 (95% CI 2.07-4.20)). Overall, ADHD was associated with elevated risk for NAPD, which is not entirely explained by shared familial factors. The clinical severity leading to medical treatment may also increase NAPD risk. Ethics approval: Approved by the ethical committee in Stockholm, Sweden (dnrs: 2010-1185-31/5 and 2013/1118-32).

Do young adolescents with first-episode psychosis or ADHD show sensorimotor gating deficits?

BACKGROUND

Early identification is important for patients with early-onset schizophrenia (SZ). Assessment of (candidate) endophenotypic markers for SZ, such as prepulse inhibition of the startle reflex (PPI), may help distinguish between the early-onset SZ and other psychiatric disorders. We explored whether PPI deficits usually seen in adult-onset SZ are present in young adolescents with either early-onset psychosis or attention deficit/hyperactivity disorder (ADHD).

METHODS

Twenty-five adolescents with first-episode, non-affective psychosis (FEP), 28 adolescents with ADHD and 43 healthy controls (HC), aged 12-17 years, were assessed with an auditory PPI paradigm.

RESULTS

No significant group differences were found in PPI. However, when the FEP group was divided into those already diagnosed with SZ (n = 13) and those without (N-SZ) (n = 12), and all four groups (SZ, N-SZ, ADHD and HC) were compared on percentage PPI in the 85/60 trials, significantly less PPI was found in patients with SZ than in the HC as well as the ADHD group. No significant group differences were found in explorative analyses on the other trial types. Additionally, startle magnitude was significantly higher in SZ than in N-SZ patients.

CONCLUSION

Young adolescents with SZ showed sensorimotor gating deficits similar to those usually found in adults with SZ and had larger startle magnitude than patients with other types of non-affective early-onset psychosis. No sensorimotor gating deficits were found in adolescents with ADHD. Our findings support the theory that deficient PPI is endophenotypic for SZ.

Behavior and Molecular Genetic Approaches to Comorbidity

Purpose of Review

This review provides an overview of studies that used behavioral genetic methods to understand the genetic and environmental influences that lead to comorbidity, the co-occurrence of two or more developmental disorders in the same individual.

Recent Findings

Comorbidity is primarily explained by shared genetic influences for most pairs of disorders that have been studied, including attention deficit hyperactivity disorder (ADHD) and learning disabilities, conduct disorder and ADHD, anxiety and depression, and anxiety and autism spectrum disorder (ASD). Molecular genetic studies indicate that the etiologies of developmental disorders are highly multifactorial, with dozens or even hundreds of genes acting in combination with environmental risk factors to lead to each individual disorder and the extensive comorbidity between disorders. Due to this complexity, current state-of-the-art studies are now combining molecular genetic data from multiple large samples to begin to achieve adequate statistical power to identify the specific genetic polymorphisms that lead to comorbidity.

Summary

An extensive literature demonstrates the pervasiveness and potential importance of comorbidity between developmental disorders, and results of family, twin, and molecular genetic studies indicate that these comorbidities may be largely explained by shared genetic influences. Additional studies are ongoing to identify the specific genetic polymorphisms that increase risk for each developmental disorder and comorbidity between disorders.

A VNTR Regulates miR-137 Expression Through Novel Alternative Splicing and Contributes to Risk for Schizophrenia

The MIR137HG gene encoding microRNA-137 (miR-137) is genome-wide associated with schizophrenia (SZ), however, the underlying molecular mechanisms remain unknown. Through cloning and sequencing of individual transcripts from fetal and adult human brain tissues we describe novel pri-miR-137 splice variants which exclude the mature miR-137 sequence termed ‘del-miR-137’ that would function to down-regulate miR-137 expression. Sequencing results demonstrate a significant positive association between del-miR-137 transcripts and the length of a proximal variable number tandem repeat (VNTR) element. Additionally, a significantly higher proportion of sequenced transcripts from fetal brain were del-miR-137 transcripts indicating neurodevelopmental splicing regulation. In-silico results predict an independent regulatory function for del-miR-137 transcripts through competitive endogenous RNA function. A case-control haplotype analysis (n = 998) in SZ implicates short VNTR length in risk, with longer lengths imparting a protective effect. Rare high risk haplotypes were also observed indicating multiple risk variants within the region. A second haplotype analysis was performed to evaluate recombination effects excluding the VNTR and results indicate that recombination of the region was found to independently contribute to risk. Evaluation of the evolutionary conservation of the VNTR reveals a human lineage specific expansion. These findings shed further light on the risk architecture of the miR-137 region and provide a novel regulatory mechanism through VNTR length and alternative MIR137HG transcripts which contribute to risk for SZ.

Impact of individualized education plans on academic success of youth with early onset schizophrenia

PURPOSE

Youth with early onset schizophrenia (EOS) are eligible for an individualized education plan (IEP) in school settings, yet often have declining academic performance over time. This study examines the impact of IEP and comorbid conditions on educational outcomes for youth with EOS.

METHOD

We used mixed models and logistic regression to answer the research questions using data from 129 youth with EOS who participated in a longitudinal study from 1998 to 2006.

RESULTS

Not all children had an IEP in all waves. Of those that did, findings demonstrated that having an IEP did not improve absenteeism or academic performance. In addition, regardless of whether they had an IEP, rates of dropping out were equal.

CONCLUSIONS

Social workers should consider more individualized approaches to IEPs for youth with EOS to target the specific complexities of the disorder as well as its implications for school success.

Overlapping and disease specific trait, response, and reflection impulsivity in adolescents with first-episode schizophrenia spectrum disorders or attention-deficit/hyperactivity disorder

BACKGROUND

Schizophrenia and attention-deficit/hyperactivity disorder (ADHD) are developmental disorders with shared clinical characteristics such as cognitive impairments and impulsivity. Impulsivity is a core feature of ADHD and an important factor in aggression, violence, and substance use in schizophrenia. Based on the hypothesis that schizophrenia and ADHD represent a continuum of neurodevelopmental impairments, the aim was to identify overlapping and disease specific forms of impulsivity.

METHODS

Adolescents between 12 and 17 years of age were assessed with the Schedule for Affective Disorders and Schizophrenia for School-aged Children - Present and Lifetime Version. Subjects with early-onset, first-episode schizophrenia spectrum disorders (EOS) (N = 29) or ADHD (N = 29) and healthy controls (N = 45) were compared on two performance measures (Information Sampling Task, Stop Signal Task) and a subjective personality trait measure of impulsivity (Barratt Impulsiveness Scale, Version 11 (BIS-11)).

RESULTS

Significantly increased reflection impulsivity was observed in ADHD but not in the EOS group. No significant response inhibition deficits (stop signal reaction time) were found in the two clinical groups. The ADHD and the EOS group showed significantly increased motor, attentional, and non-planning subtraits of impulsivity.

CONCLUSIONS

Impaired pre-decisional information gathering appeared to be specific for ADHD while the information gathering was not significantly reduced in subjects with EOS. Neither the ADHD nor EOS group showed impaired response inhibition but shared increased personality subtraits of attentional, non-planning, and motor impulsivity although the latter was significantly more pronounced in ADHD. These increased subtraits of impulsivity may reflect diagnostic non-specific neurodevelopmental impairments in ADHD and EOS in adolescence.

Associations of attention-deficit/hyperactivity and other childhood disorders with psychotic experiences and disorders in adolescence

Prodromal symptoms of psychosis are associated with an increased risk of transition, functional impairment, poor mental health, and unfavorable developmental prospects. Existing interventions targeting the prodrome are non-satisfactory. It may thus be more promising to attempt to identify risk factors in the premorbid phase preceding the prodrome to increase the chances of successful preventive approaches. Here, we investigate whether childhood mental disorders in general and attention-deficit/hyperactivity disorder (ADHD) specifically indicate a risk for subsequent psychotic experiences and disorders. We used a sample from the prospective Avon Longitudinal Study of Parents and Children (N = 5528). When the participants were 7 years old, mental disorders were assigned according to the DSM-IV. In standardized interviews, psychotic experiences were assessed at age 12 and psychotic disorders at age 18. We examined the associations of each of the childhood mental disorders alone and in combination with psychotic experiences at age 12 and psychotic disorders at age 18 using logistic regression. Compared to participants without a disorder, participants with a mental disorder had a higher risk of psychotic experiences at age 12 (OR 1.70, 95 % CI 1.28-2.27) and of psychotic disorders at age 18 (OR 2.31, 95 % CI 1.03-5.15). Particularly, the ADHD combined subtype at age 7 was strongly associated with psychotic experiences at age 12 (OR 3.26, 95 % CI 1.74-6.10). As expected, childhood mental disorders are risk indicators of psychotic experiences and disorders. To improve prevention, health care professionals need to screen for psychotic experiences in children with non-psychotic disorders.

Cortical morphology as a shared neurobiological substrate of attention-deficit/hyperactivity symptoms and executive functioning: a population-based pediatric neuroimaging study

BACKGROUND

Attention-deficit/hyperactivity symptoms have repeatedly been associated with poor cognitive functioning. Genetic studies have demonstrated a shared etiology of attention-deficit/hyperactivity disorder (ADHD) and cognitive ability, suggesting a common underlying neurobiology of ADHD and cognition. Further, neuroimaging studies suggest that altered cortical development is related to ADHD. In a large population-based sample we investigated whether cortical morphology, as a potential neurobiological substrate, underlies the association between attention-deficit/hyperactivity symptoms and cognitive problems.

METHODS

The sample consisted of school-aged children with data on attention-deficit/hyperactivity symptoms, cognitive functioning and structural imaging. First, we investigated the association between attention-deficit/ hyperactivity symptoms and different domains of cognition. Next, we identified cortical correlates of attention-deficit/hyperactivity symptoms and related cognitive domains. Finally, we studied the role of cortical thickness and gyrification in the behaviour-cognition associations.

RESULTS

We included 776 children in our analyses. We found that attention-deficit/hyperactivity symptoms were associated specifically with problems in attention and executive functioning (EF; b = -0.041, 95% confidence interval [CI] -0.07 to -0.01, p = 0.004). Cortical thickness and gyrification were associated with both attention-deficit/hyperactivity symptoms and EF in brain regions that have been previously implicated in ADHD. This partly explained the association between attention-deficit/hyperactivity symptoms and EF (b_indirect = -0.008, bias-corrected 95% CI -0.018 to -0.001).

LIMITATIONS

The nature of our study did not allow us to draw inferences regarding temporal associations; longitudinal studies are needed for clarification.

CONCLUSION

In a large, population-based sample of children, we identified a shared cortical morphology underlying attention-deficit/hyperactivity symptoms and EF.

Mismatch negativity and P3a amplitude in young adolescents with first-episode psychosis: a comparison with ADHD

BACKGROUND

Deficient mismatch negativity (MMN) has been proposed as a candidate biomarker in schizophrenia and may therefore be potentially useful in early identification and intervention in early onset psychosis. In this study we explored whether deficits in the automatic orienting and reorienting responses, measured as MMN and P3a amplitude, are present in young adolescents with first-episode psychosis (FEP) and whether findings are specific to psychosis compared to young adolescents with attention deficit hyperactivity disorder (ADHD).

METHOD

MMN and P3a amplitude were assessed in young adolescents (age 12-17 years) with either FEP (N = 27) or ADHD (N = 28) and age- and gender-matched healthy controls (N = 43). The MMN paradigm consisted of a four-tone auditory oddball task with deviant stimuli based on frequency, duration and their combination.

RESULTS

Significantly less MMN was found in patients with psychosis compared to healthy controls in response to frequency and duration deviants. MMN amplitudes in the group of patients with ADHD were not significantly different from patients with psychosis or healthy controls. No significant group differences were found on P3a amplitude.

CONCLUSION

Young adolescents with FEP showed impaired MMN compared to healthy controls while intermediate and overlapping levels of MMN were observed in adolescents with ADHD. The findings suggest that young FEP patients already exhibit pre-attentive deficits that are characteristic of schizophrenia albeit expressed on a continuum shared with other neuropsychiatric disorders.

A systematic review of transcranial electrical stimulation combined with cognitive training

BACKGROUND

Transcranial Electrical Stimulation (tES) methods have been shown to enhance performance across a range of cognitive tasks. It is thought that tES can be used to enhance the treatment-effects of cognitive training (CT), leading to lasting improvements in neurocognitive function. Recently, a small number of studies have investigated the effects of tES combined with CT in healthy and cognitively impaired subjects.

OBJECTIVE

To evaluate the effects of tES + CT on both CT task performance and on non-trained cognitive outcomes.

METHODS

A systematic review was conducted in accordance with PRISMA guidelines. Databases (PsycINFO, EMBASE, PubMed and Medline) were searched for all randomized, controlled and naturalistic prospective studies up until June 2014, combining tES and CT.

RESULTS

13 studies comprising 465 participants met the inclusion criteria. Findings indicated that tES + CT enhanced performance on the majority of CT tasks. The effects on non-trained tasks were mixed, with some evidence for improvements in working memory, cognitive control, approximate number sense and arithmetic processing.

CONCLUSIONS

tES + CT enhances performance on CT tasks across a range of cognitive functions. Preliminary evidence suggests that tES may also increase transfer effects to non-trained tasks in some domains. Recommendations for future studies are provided.

Attention-deficit/hyperactivity disorder, methylphenidate use and the risk of developing schizophrenia spectrum disorders: A nationwide population-based study in Taiwan

This study estimated the risk of developing psychotic disorders by comparing children with ADHD to non-ADHD controls, and to examine whether methylphenidate (MPH) treatment influences the risks of psychotic disorders. A nationwide cohort of patients who were newly diagnosed with ADHD (n=73,049) and age- and gender-matched controls (n=73,049) were selected from Taiwan's National Health Insurance database from January 2000 to December 2011. All participants were observed until December 31, 2011. Cox regression models were used to estimate the effects of ADHD diagnosis and MPH use on subsequent outcomes. Having a diagnosis of any psychotic disorder and of schizophrenia were set as two different outcomes and were analyzed separately. Compared to the control group, the ADHD group showed significantly increased risk of developing any psychotic disorder (adjusted hazard ratio [aHR], 5.20; 95% confidence interval [CI], 4.30-6.30) and schizophrenia (aHR, 4.65; 95% CI, 3.59-6.04). Compared to ADHD patients without psychosis, patients with ADHD who developed psychosis had significantly older age at first diagnosis of ADHD (9.4±3.3years vs. 10.6±4.0years). Among patients with ADHD, MPH use significantly increased the risk of developing any psychotic disorder (aHR, 1.20; 95% CI, 1.04-1.40), but did not increase the risk of developing schizophrenia (aHR, 1.16; 95% CI, 0.94-1.42). The results indicated that previous diagnoses of ADHD are a powerful indicator of developing psychotic disorders. Nevertheless, the specific mechanisms of the relationships between ADHD, MPH use and psychotic disorders need further elucidation in future clinical studies.