Cerebral dominance and schizophrenia-spectrum disorders in adults with intellectual disability

Studies of the general population without intellectual disability have suggested an association between atypical handedness and schizophrenia‐spectrum disorders (SSDs). Mixed handedness is taken as an index of diminished cerebral dominance or laterality. The present study addressed the question of whether such findings extend to the neurodevelopmentally ‘at risk’ population of adults with intellectual disability and SSDs compared with appropriate controls. Fourteen patients with a dual diagnosis of intellectual disability and SSD were compared with 14 controls with intellectual disability alone. Assessments of self‐reported hand preference and relative hand skill were completed. Self‐report of hand preference revealed highly significantly greater mixed‐handedness in the SSD group. Furthermore, relative hand skill performance was significantly diminished for the dominant hand. The discrepancy between dominant and non‐dominant hand functioning was lower in the SSD group and this association was highly significant. The results of the present study support the usefulness of such detailed laterality assessment in this population. Mixed laterality, over and above that of the population with general intellectual disability and developmental disorder, was associated with SSD. These results are consistent with the neurodevelopmental hypothesis of schizophrenia and its cognitive neuropsychiatric/neuropsychological sequelae.     

Solving the Raven Progressive Matrices by adults with intellectual disability with/without Down syndrome: different cognitive patterns as indicated by eye-movements

Raven matrices are used for assessing fluid intelligence and the intellectual level of groups with low intelligence. Our study addresses qualitative analysis of information processing in Raven matrices performance among individuals with intellectual disability with that of their typically developed (TD) counterparts. Twenty-three adults with non-specific intellectual disability (NSID), 15 adults with Down syndrome (DS) and 35 children with TD matched for mental age, participated. Participants solved the Raven's Colored Progressive Matrices and five items from the Raven Standard Progressive Matrices while having their eye movements monitored. The overall percent of correct answers was significantly higher for the TD group compared to two ID group. Comparison of the eye movement pattern of each group indicated that the TD group spent more time on the matrices before shifting to the options, than the two ID groups. The TD group made significantly less switches from one rejoins to another, than the ID groups. The difference in the scanning pattern between the TD and the ID groups is interpreted as a reflection of two different types of strategies, Constructive matching and Response elimination, respectively. There were no differences in eye scanning between participants with NSID and those with DS.     

Handedness prevalence in the deaf: Meta-analyses

An under-investigated aspect of handedness, a biological proxy for cerebral laterality for language, is its prevalence amongst deaf individuals. We present four sets of meta-analyses on studies measuring handedness prevalence in deaf individuals, comprising 31 data sets and totaling 5,392 participants (4,606 deaf, 786 hearing). Deaf individuals were found to be 2.61 times more likely to be non-right-handed and 2.25 times more likely to be left-handed compared to their hearing counterparts. When handedness was measured by means of manipulative actions, the weighted estimates of handedness prevalence for deaf populations were 17.70% and 14.70% for non-right- and left-handedness respectively; when handedness was measured by means of sign actions, the prevalence was 10.60% and 9.70%, respectively. Yet, when comparing studies that measured handedness in the same deaf individuals using both manipulative and sign actions, no difference was found in their handedness prevalence. This pattern is taken to suggest that the higher prevalence of atypical handedness in the deaf population may be linked to delayed language acquisition.     

Analogies solving by individuals with and without intellectual disability: Different cognitive patterns as indicated by eye movements

Eighteen adults with intellectual disability (ID) and 20 children with typical development (TD) matched for cognitive level, participated in this study. Participants solved perceptual and conceptual analogies (from the Conceptual and Perceptual Analogical Modifiability Test—CPAM) while having their eye movements monitored. As predicted, the overall percent of correct answers was significantly higher for the TD group compared to that of the ID group. Comparison of the eye movement pattern of each group while solving the analogies revealed that in addition to the quantitative difference between the groups, there is a qualitative difference in the process of solving the analogies. The difference in the scanning pattern between the TD and the ID groups is interpreted as a reflection of two different types of strategies, Constructive matching and Response elimination, respectively.     

How could Theory of Mind contribute to the differentiation of social adjustment profiles of children with externalizing behavior disorders and children with intellectual disabilities?

This study compared Theory of Mind (ToM) emotion and belief abilities in 43 children with externalized behavior (EB) disorders presenting low intelligence, 40 children with intellectual disabilities (ID) and 33 typically developing (TD) preschoolers (as a control group), matched for developmental age. The links between their ToM abilities, their level in seven self-regulation strategies as displayed in social problem-solving tasks and their social adjustment profiles (assessed by the Social Competence and Behavior Evaluation, completed by their teachers) were examined. Children with EB presented lower comprehension of causes of emotions and lower self-regulation of joint attention and of attention than children with ID and TD children. In comparison with TD children, lower social adjustment was observed in nearly all dimensions of profiles in both atypical groups. Specifically, children with EB were significantly angrier than children with ID. Although variable patterns of positive correlations were obtained in atypical groups between self-regulation strategies and ToM abilities, the most numerous positive links were obtained in the group with EB. Regression analyses showed that developmental age predicted ToM abilities and certain dimensions of social adjustment profiles in atypical groups. In the ID group, ToM emotions predicted general adaptation, affective adaptation, interactions with peers and with adults and low internalizing problems. In the EB group, general adaptation was predicted by ToM emotions and self-regulation, interactions with peers by ToM beliefs, and a low level of externalizing problems by ToM emotions. Some implications for intervention and perspectives for research are suggested.     

Environmental risk factors associated with the persistence of conduct difficulties in children with intellectual disabilities and autistic spectrum disorders

We investigated the association between exposure to environmental risks in early childhood and the prevalence and persistence of conduct difficulties (CD) in children with intellectual disability (ID) who did not have autistic spectrum disorder (ASD), children with ASD and typically developing (TD) children. Results indicated that: (1) exposure to risk was associated with elevated prevalence of CD at age three and, for TD children and children with ID, increased risk of CD persisting to ages five and seven; (2) at all levels of risk, children with ASD were more likely to show persistent CD than other children; (3) children with ID were no more likely to show persistent CD than TD children at low levels of exposure to environmental risk.     

Characterizing associations and dissociations between anxiety,social, and cognitive phenotypes of Williams syndrome

Williams syndrome (WS) is a neurogenetic disorder known for its “hypersocial” phenotype and a complex profile of anxieties. The anxieties are poorly understood specifically in relation to the social-emotional and cognitive profiles. To address this gap, we employed a Wechsler intelligence test, the Brief Symptom Inventory, Beck Anxiety Inventory, and Salk Institute Sociability Questionnaire, to (1) examine how anxiety symptoms distinguish individuals with WS from typically developing (TD) individuals; and (2) assess the associations between three key phenotypic features of WS: intellectual impairment, social-emotional functioning, and anxiety. The results highlighted intensified neurophysiological symptoms and subjective experiences of anxiety in WS. Moreover, whereas higher cognitive ability was positively associated with anxiety in WS, the opposite pattern characterized the TD individuals. This study provides novel insight into how the three core phenotypic features associate/dissociate in WS, specifically in terms of the contribution of cognitive and emotional functioning to anxiety symptoms.     

Solution-Focused Approaches in the Context of People With Intellectual Disabilities: A Critical Review

Introduction: Solution-focused brief therapy (SFBT) has a growing evidence base and several authors have recognized the advantages of applying this approach with people with intellectual disabilities (ID). The purpose of this review is to summarize and critique the literature that has used solution-focused (SF) approaches in ID, and consider future directions. Methods: A literature review was carried out, identifying 12 studies; six with individuals, and six with staff and families. Results: There is preliminary evidence for the effectiveness of SFBT for individuals with mild ID and Solution-Focused Coaching or Consultation (SFC) for staff working with individuals with moderate and severe ID. However, the current evidence base consists primarily of case studies. Recommended adaptations include shortened scales and more concrete approaches to eliciting exception-seeking. Conclusions: Solution-focused techniques should be modified to accommodate the cognitive abilities of people with ID and carers should be involved in sessions where possible. There is a need for further controlled studies, with valid and reliable outcome measures, larger samples, and longitudinal data.     

Receptive vocabulary analysis in Down syndrome

The present study is an in-depth examination of receptive vocabulary in individuals with Down syndrome (DS) in comparison to control groups of individuals of similar nonverbal ability with typical development (TD) and non-specific etiology intellectual disability (ID). Verb knowledge was of particular interest, as it is known to be a predictor of later syntactic development. Fifty participants with DS, aged 10–21 years, 29 participants with ID, 10–21 years, and 29 participants with TD, 4–9 years, completed measures of receptive vocabulary (PPVT-4), nonverbal ability (Leiter-R), and phonological memory (Nonword Repetition subtest of the CTOPP). Groups were compared on percentage correct of noun, verb and attribute items on the PPVT-4. Results revealed that on verb items, the participants with ID performed significantly better than both participants with DS and TD, even when overall receptive vocabulary ability and phonological memory were held constant. Groups with DS and TD showed the same pattern of lexical knowledge, performing better on nouns than both verbs and attributes. In contrast, the group with ID performed similarly on nouns and verbs, but worse on attributes.     

Daily living skills in adolescents with autism spectrum disorder: Implications for intervention and independence

BackgroundChallenges in adaptive behaviors are present in individuals with autism spectrum disorder (ASD), while variation in IQ, social skills, and comorbidities are possible influences on adaptive behaviors. However, adaptive behaviors do not consistently map onto cognitive abilities in ASD, as high IQ is not protective against challenges in adaptive behaviors. Additionally, individuals with both ASD and elevated levels of externalizing problem behaviors experience even worse adaptive behaviors. Identifying factors that contribute to the variance in adaptive behaviors, particularly daily living skills (DLS), may inform strategies to improve adaptive behaviors necessary for independence in adulthood.MethodAdolescents with typical cognitive development (TD, n = 84), intellectual disability (ID, n = 30), or ASD (n = 45) were included in this study to examine group differences in adaptive behaviors, identify relations between IQ and DLS, and determine factors that contribute to variance in DLS at youth age 13. The Vineland Adaptive Behavior Scales, 2nd Edition (VABS-II) was used to measure adaptive behaviors.ResultsAll domains of adaptive behavior were significantly higher in TD groups compared to ASD and ID youth. Significant positive correlations were observed between IQ and DLS in the ASD and ID groups. In the ASD youth group, higher externalizing behavior problems explained the most variance in DLS.ConclusionsDLS are below age-expected levels in young adolescents with ASD, in part because of the higher externalizing behavior problems in this group. Incorporating adaptive skills training and behavior management strategies into current interventions may serve to prepare adolescents and families for the transition to adulthood.     

Intellectual Disability and Psychotic Disorders of Adult Epilepsy

Summary:  Purpose: To investigate the prevalence, psychopathology, and cognitive functions associated with psychotic disorders among adult epilepsy patients with intellectual disability (ID) based on a multicenter study in Japan.
Methods: The study was divided into three phases; a prevalence study of psychotic disorders among new referrals of epilepsy, a polydiagnostic comparative study of patients with psychotic epilepsy and those with schizophrenia, and a neuropsychological study of patients with psychotic epilepsy and education level–matched controls.
Results: Among 336 new referrals of epilepsy, a higher prevalence of psychotic disorders was found among patients with ID (24%) than among those with normal intelligence (6%). The psychotic symptoms and operational diagnoses of psychotic epilepsy patients with ID were similar to those of patients with normal intelligence. A wide range (7–86%) of psychotic epilepsy patients was diagnosed as having schizophrenia, depending on the operational criteria used. Patients with psychotic epilepsy had more disturbances in verbal memory and attention functions than did the controls.
Conclusions: Epilepsy patients with ID show a predisposition to develop psychotic disorders. Distinguishing their psychotic symptoms from those of schizophrenia is difficult. Subtle cognitive disturbances predispose to psychotic disorders in epilepsy.     

Self-perception,self-regulation and metacognition in adolescents with intellectual disability

This study compares self-perception of competences in 28 typically developing children (TD) aged 7–9 years and 32 adolescents with intellectual disability (ID) aged 11–16 years in special school, matched for mental age (MA). The links between self-perception, self-regulation in problem-solving and metacognition are investigated. Overall self-perception and self-perception of competences by domain do not differ significantly between the two groups. Self-perception of competences in specific domains, self-regulation and metacognition vary depending on MA and verbal comprehension in the two groups. ID adolescents attribute more importance to social acceptance than TD children. In both groups, positive links are identified between self-perception and importance attributed to domains. Performance, self-regulation and metacognition are lower in ID adolescents than in TD children. Positive links are obtained between self-perception of competences in specific domains and certain self-regulatory and metacognitive strategies, although these links differ in the two groups.     

Predictors of early literacy skills in children with intellectual disabilities: A clinical perspective

The present study investigated the linguistic and cognitive predictors of early literacy in 17 children with intellectual disabilities (ID) (mean age: 7; 6 years) compared to 24 children with normal language acquisition (NLA) (mean age: 6; 0 years), who were all in the so-called partial alphabetic phase of reading (Ehri, 2005). In each group, children's performances in early literacy skills (phonological awareness, letter knowledge, and word decoding) were assessed, as well as their achievement in linguistic and cognitive measures associated to these skills. The results showed that, notwithstanding the fact that there were no differences in word decoding, children with ID lagged behind on all predictor measures relevant to early literacy skills compared to children with NLA. Moreover, whereas children with NLA showed a regular predictive pathway of early literacy skills, children with ID showed a deviant pattern, in which nonverbal intelligence and rhythmic skills proved to be of major importance. Also letter knowledge appeared to be involved in their early literacy processing. It can be tentatively concluded that in the ID group, children's level of nonverbal intellectual abilities in combination with rhythmic ability proves pivotal in the development of their early literacy skills.     

The Prevalence and Characteristics of Intellectual and Borderline Intellectual Disabilities in a Sample of Inpatients with Substance Use Disorders: Preliminary Clinical Results

Introduction: There is reason to believe that many individuals with substance use disorders (SUD), who are in contact with services, have an undiagnosed intellectual disability. The aim of the present study was to investigate the prevalence of intellectual and borderline intellectual disabilities (ID/BID) among inpatients with SUD and to further explore their characteristics. Methods: Ninety-one SUD inpatients aged 19–64 participated in the study. SUD was diagnosed according to the ICD-10. ID/BID was diagnosed through the Wechsler Adult Intelligence Scale, the Vineland Adaptive Behavior Scale, and self-reported childhood learning difficulties. Results: ID/BID prevalence was up to 30%. There were significant differences between ID/BID and non-ID groups for several social variables. With the exception of substance-use relapse, there were no significant differences in substance-related factors. Conclusions: ID/BID prevalence in SUD might be high. These conditions often go undiagnosed in SUD treatment. The conditions and associated difficulties should be identified for better understanding and individually adapted treatment.     

Working memory,intelligence and knowledge base in adult persons with intellectual disability

Previous studies have suggested that performance in working memory (WM) tasks is deficient in all etiologies and at all levels of intellectual disability (ID). Knowledge about WM structure, cognitive processes reflected in WM tasks, or the long-term memory contribution to WM capacity in ID is. however, not satisfactory. In the present study, WM capacity, WM task requirements, as well as effects between WM, skills, knowledge base, and intelligence were explored in two groups with matched fluid intelligence: adult persons with ID and normally developing children aged 3-6 years. The ID Group performed equally well as the children in WM tasks based on familiar semantic information and were significantly better on all measures reflecting skills and knowledge base. The Child Group performed better in phonological and visuo-spatial WM tasks including nonsemantic information, respectively. In particular, it appeared that the groups differed in their WM performance although they were matched for fluid intelligence. We hypothesize that the ID Group depended more on knowledge support from long-terrm memory whereas the Child Group could benefit more from efficient online WM processes.     

Bullying of youth with autism spectrum disorder,intellectual disability,or typical development: Victim and parent perspectives

In-depth interviews conducted separately with 13-year-olds with autism spectrum disorder (ASD), intellectual disability (ID), or typical development (TD) and their mothers investigated the experiences of victimization in the form of bullying. Coded constructs from the interviews were utilized to compare groups on the frequency, type, and impact of victimization. Youth with ASD were victimized more frequently than their ID or TD peers, and the groups differed with regard to the type of bullying and the impact it had, with ASD youth faring the worst. Higher internalizing problems and conflict in friendships were found to be significant predictors of victimization, according to both youth- and mother-reports. These predictors were found to be more salient than ASD status alone. Implications for practice are discussed.     

Cognitive and emotional intelligence in young adults with Autism Spectrum Disorder without an accompanying intellectual or language disorder

Research in the neurosciences has identified distinctions between neural structures that subserve cognitive intelligence (CI) and those subserving emotional intelligence (EI). This study explored the performance of young adults with Autism Spectrum Disorder (ASD) without an accompanying intellectual or language disorder relative to typically-developing peers, on indices of CI and EI. Both the ASD and age- and sex-matched typically-developing groups exhibited high average cognitive intellectual abilities. In contrast, the ASD group reported lower levels of EI relative to their typically-developing peers, as expected given the social and emotional challenges faced by individuals with ASD. Importantly, cognitive intelligence did not correlate with EI in either group. Taken together, these findings further support the theory of dissociable neural systems underlying CI and EI. These findings also highlight the need to address not only the intellectual aspects of cognition, but also the emotional components to increase understanding of, and improve treatment for individuals on the autism spectrum. This understanding would enhance our ability to assess and support young adults with ASD, and ultimately ease their transition into adulthood.     

Outpatient physical therapy utilization for children and adolescents with intellectual disabilities in Taiwan: A population-based nationwide study

This study analyzed the utilization and utilization determinants of outpatient physical therapy (PT) among children and adolescents with intellectual disabilities (ID) in Taiwan. A cross-sectional study was conducted to analyze 2007 national health insurance (NHI) claim data from 35,802 eighteen-year-old and younger persons with intellectual disabilities. A total of 3944 (11.02%) claimants received outpatient physical therapy. Variables that affected PT utilization included age, residence urbanization level, ID level, copayment status and major co-morbidity. The average annual PT visit frequency was 25.4 ± 33.0; pre-school children, claimants suffering from catastrophic disease and ID co-occurring with cerebral palsy had a higher mean cost per visit. Age, ID level, copayment status and co-morbidity were factors that influenced expenditure. Pre-school children, males, individuals who resided in the lowest urbanization areas and individuals with a catastrophic disease tended to use hospital services. The point prevalence of epilepsy and cerebral palsy were 12.10% and 19.80%, respectively. Despite the NHI program and government regulations to provide special services, the use of physical therapy for children and adolescents with intellectual disabilities was low, and the utilization decreased as the subjects aged.     

Sleep electroencephalography and brain maturation: developmental trajectories and the relation with cognitive functioning

Sleep has a crucial role in brain functioning and cognition, and several sleep electroencephalography (EEG) hallmarks are associated with intellectual abilities, neural plasticity, and learning processes. Starting from this evidence, a growing interest has been raised regarding the involvement of the sleep EEG in brain maturation and cognitive functioning during typical development (TD). The aim of this review is to provide a general framework about the maturational changes and the functional role of the human sleep EEG during TD from birth to late adolescence (≤22 years). The reviewed findings show large developmental modifications in several sleep EEG hallmarks (slow wave activity, sleep spindles, theta activity, and cyclic alternating pattern) during TD, and many studies support the notion of an active role of sleep slow wave activity in supporting brain maturation. Moreover, we focus on the possible relation between sleep microstructure, intelligence, and several memory domains (declarative, emotional, procedural), showing that sleep EEG oscillations seem involved in intellectual abilities and learning processes during TD, although results are often conflicting and divergent from findings in adults. Starting from the present literature, we propose that larger methodological uniformity, greater attention to the topographical and maturational aspects of the sleep EEG oscillations and their mutual interactions, and a higher number of longitudinal studies will be essential to clarify the role of the sleep EEG in cognitive functioning during TD.