Executive functions in individuals with intellectual disability

Exploration of a somatosensory interactive assessment tool for children with intellectual disabilities

Based on the functional assessment concept and embodied assessment requirements, the present study aimed to design and develop an assessment tool for children with intellectual disabilities with the help of somatosensory interactive (SI) technology. The sample in this study consisted of 73 children with intellectual disabilities and 70 children with typical development. Data were collected through three SI tasks, four traditional executive function tasks, and user experience interviews to analyse the effectiveness of the SI assessment tool. The results showed that the SI assessment tool had good scale validity, discriminant validity, and the ability to identify intellectual disabilities. Children preferred SI tasks and showed higher involvement and more positive emotions. The SI tool with three SI tasks is a more scientific, effective, and advanced tool for assessing children with intellectual disabilities.

Far Transfer Effects of Trainings on Executive Functions in Neurodevelopmental Disorders: A Systematic Review and Metanalysis

Executive Functions are a set of interrelated, top-down processes essential for adaptive goal-directed behaviour, frequently impaired across different neurodevelopmental disorders with variable degrees of severity. Many executive-function-training studies in children with neurodevelopmental disorders have focused on near effects, investigating post-treatment improvements on directly trained processes, while enhancements of skills not directly trained, defined as far effects, are less considered, albeit these could be extremely relevant for reducing the negative impact of a disorder's core symptomatology. This systematic review and metanalysis aims to investigate the far effect outcomes after EF training in children with different types of neurodevelopmental disorders. 17 studies met the inclusion criteria for the systematic review, while 15 studies were selected in the metanalysis. An overall statistically significant effect size was found in the majority of far effect outcome measures considered in the studies. In particular, trainings on executive functions determine significant far effects on daily life functioning (0.46, 95% CI: [0.05-0.87]) and clinical symptoms (0.33, 95% CI: [0.15-0.51]). Despite a high variability of the results, intensity, frequency and the laboratory/life contexts dimension seem to be the most influential variables in determining far effects. This systematic review and metanalysis highlights the need to measure far effects of executive function training in neurodevelopmental disorders, selecting treatments not only on directly targeted processes, but also according to far impacts on the functional weakness of the disorder.

Attentional Resources and Independence in Basic and Instrumental Activities of Daily Living in Individuals with Intellectual Disabilities

The relationship between attentional resources and functionality in individuals with intellectual disabilities (IDs) is clinically relevant. This study aimed to examine the possible relationship between the degree of ID and attentional resources, and to evaluate whether attentional resources predict the performance of basic and instrumental activities of daily living (ADL) in individuals with mild and moderate ID. This study, which employed a descriptive, cross-sectional, observational design, was conducted between July 2019 and May 2020. The sample consisted of 166 individuals divided into three groups: moderate ID, mild ID, and those without ID. These groups were compared for attentional functions (p < 0.001), obtaining an effect size ranging from medium to large. The results indicated that 40% of the variance in basic ADL performance was explained by the age of the participants, degree of disability, and sustained attention in individuals with ID. Additionally, 64% of the variance in instrumental ADL performance was explained by sustained, divided, and executive attention. Therefore, attentional resources appear to be associated with the performance of basic and instrumental ADL in individuals with mild and moderate ID.

Cognitive and functional evolution in older adults with and without intellectual disability using a multicomponent intervention: A prospective longitudinal study

BACKGROUND

The global population is experiencing accelerated biopsychosocial aging. Cognitive impairment is frequently associated with functional impairment in basic and instrumental daily living activities. To maintain optimal cognitive and functional functioning, health professionals recommend that older adults participate in cognitive training.

AIMS

This study examines the cognitive and functional evolution of older adults with and without Intellectual Disability and the factors associated with favourable evolution following the intervention of a multicomponent programme based on the human occupational model and the person-centred care model.

METHODS AND PROCEDURES

247 people participated. Descriptive and univariate analyses were performed to examine baseline data. The Wilcoxon paired samples test was used to compare cognitive and functional evolution one year after the intervention. Linear regression was used to detect factors predicting favourable evolution.

OUTCOMES AND RESULTS

Both populations improved cognitively. There was no change in basic activities of daily living. There was an improvement in instrumental activities of daily living in the group with Intellectual Disability. None of the variables collected was a predictor of greater improvement.

CONCLUSIONS AND IMPLICATIONS

This study demonstrated that older people with Intellectual Disability who have supports to cope with this life stage can improve their cognitive and functional abilities.

The Association between Executive Function and Performing Instrumental Daily Activities in People with Intellectual Disabilities

Institutionalized individuals with intellectual disabilities have few opportunities to participate in instrumental activities of daily living (IADLs), which probably affects higher cognitive functions, or vice versa. The objectives of this study were to evaluate the possible difference in the ability to perform IADLs and executive functioning between individuals with and without intellectual disabilities and to determine if executive functions are associated with the performance of IADLs in people with intellectual disabilities. This was a multi-center cross-sectional study, conducted between July 2019 and May 2020. Participants with intellectual disabilities were recruited from four centers for people with intellectual disabilities. Adults without these disabilities were gathered from several community centers. The sample consisted of 90 individuals with moderate intellectual disabilities and 79 individuals with no intellectual disability. Executive functions were evaluated using the Wechsler Adult Intelligence Scale-WAIS-IV, the INECO Frontal Screening test, the Semantic Verbal Fluency Test, and the Behavioural Assessment of the Dysexecutive Syndrome-BADS-Scale. The performance of the IADLs was assessed by the Lawton and Brody Scale. The results showed that the higher the function in instrumental activities, the lower the impairment of executive functions. Executive functions accounted for 81% of the total variance in the ability to perform the IADLs. In conclusion, individuals with moderate intellectual disabilities demonstrated limitations in executing the IADLs, which were partially associated with low performance in executive functions. This information could help in the development of evidence-based intervention programs and facilitate the formulation of appropriate support strategies to enhance participation in these activities.

Psychometric evaluation of a working memory assessment measure in young children with Down syndrome

BACKGROUND

Working memory involves the temporary storage and manipulation of information and is frequently an area of challenge for individuals with Down syndrome (DS). Despite the potential benefits of intervention, laboratory assessments of working memory that could capture intervention effects have not undergone rigorous evaluation for use with young children with DS. It is critical to evaluate assessments of working memory in young children with DS to ensure the reliable and accurate measurement of performance.

AIM

This study evaluated an adapted laboratory measure of working memory for young children with DS 2-8 years old.

METHOD

A self-ordered pointing task, the Garage Game, was administered to 78 children with DS (mean = 5.17 years; SD = 1.49). Adaptations were made to the task to minimize potential DS phenotype-related language and motor confounds.

RESULTS

Results indicate that the measure is feasible, scalable, and developmentally sensitive, with minimal floor and practice effects for this population within this chronological and developmental age range.

CONCLUSION

These findings demonstrate that the Garage Game is promising for use in studies of early working memory and treatment trials that aim to support the development of this critical dimension of executive functioning for children with DS.

Serious Games for Executive Functions Training for Adults with Intellectual Disability: Overview

(1) Background: Throughout the history of medical and psychology practice, specialists have worked to improve the quality of treatment and rehabilitation, which has led to the emergence of concepts such as serious games. These tools focus on different areas of intervention procedures, one of which is to help people with intellectual disability (ID). Individuals with ID have problems with executive functions (EFs), which are related to adaptive functioning. Recent studies showed that serious games positively impact cognitive, social, and communication skills in people with ID. The purpose of this study is to analyze the solutions that have been found in EF training for adults with ID in recent years, evaluating them with a number of key parameters and identifying the features and possible problems in the further development of our system. (2) Methods: A review was conducted starting with 573 articles in English related to serious games and selected from studies that had been published since 2015. Finally, 10 were examined in detail as they focused on EFs in adults with ID. They were searched in seven major databases ("Association for Computing Machinery" (ACM), IEEE Xplore database, DBLP computer science bibliography, Google Scholar, PubMed, SCOPUS, and PsycInfo). (3) Results: It was determined that the most frequent EFs referred to in the studies analyzed were planning and decision-making, followed by working memory and social cognition, behavioral regulation, flexibility, and inhibition capacity. The basic approach to the creation of support systems was also analyzed in terms of technical and program execution. The trend results' analysis evidenced improvements in EFs, even though they were not significant. This comprehensive technique enabled the identification of the main features and aspects to be taken into account for further development of our system.

Dutch forensic patients with and without intellectual disabilities: A comparison of demographic, offence, and diagnostic characteristics

BACKGROUND

Patients with an intellectual disability (ID) and offending histories constitute a challenging clinical group. The present study examined commonalities and differences in demographic, diagnostic and offence characteristics in patients with and without intellectual disabilities who were either convicted for violent or sexual offences and who resided in mandated care in the Netherlands.

METHOD

We compared 165 offenders with an ID to 249 offenders without an ID. We compared both groups by type of offence (i.e., sexual versus violent offence) using Mann-Whitney U-test or independent samples t-tests for continuous variables and Chi-square tests for categorical variables.

RESULTS

In general, forensic patients with an ID were younger at admission (U=357, z = -12.668, p < .001), had more prior convictions for violent offences (χ²(1)= 6.175, p = .013) and more prevalent diagnoses of substance abuse disorders (χ²(1)= 9.266, p = .002) than those without an ID. Similar results were found for patients with IDs with sexual offence histories.

CONCLUSION

A clear understanding of distinct characteristics of forensic patients with intellectual disabilities is crucial in understanding (sexual) violent behavior in this population as it mayassistclinicians in prioritizing interventionstrategies.

Caregiver-reported executive functioning and associated adaptive and challenging behaviour in children with histories of developmental delay

BACKGROUND

Deficits in executive functioning (EF) have been measured in individuals with developmental disabilities, such as autism spectrum disorder and attention-deficit/hyperactivity disorder, through the use of behaviour rating scales and performance-based assessment. Associations between EF and variables such as challenging and adaptive behaviour have been observed; however, limited research exists on EF profiles in children with heterogeneous developmental delay or with intellectual disability (ID) or the impact of EF on adaptive and challenging behaviour with this population.

METHODS

The present study sought to examine the EF profile of 93 children (75 male and 18 female) previously identified with developmental delay in early childhood. EF was assessed using the Behaviour Rating Inventory of Executive Function, Second Edition (BRIEF-2). Children were categorised into an ID group (n = 14) or no ID group (n = 79) based on scores from cognitive and adaptive behaviour assessments. EF profiles were investigated and compared by group. In addition, the impact of EF on both adaptive behaviour and challenging behaviour was measured using hierarchical linear regressions.

RESULTS

Statistically significant differences in caregiver-reported EF were not observed between groups; however, both the ID and the no ID group scores were elevated as reported by their caregivers. For the overall sample, caregiver-EF accounted for significant variance in both adaptive (22%) and challenging (68%) behaviour after accounting for child age and sex.

CONCLUSIONS

Results indicated deficits in EF for children with and without ID. The significance of EF was accounted for in both adaptive and challenging behaviour for all children in the sample. Future research could elucidate the role of adaptive and challenging behaviour in understanding EF variability among children with histories of developmental delay.

A meta-analysis of the executive function components inhibition, shifting, and attention in intellectual disabilities

BACKGROUND

Executive function is a concept for higher-order cognitive functions, which have the role of controller and modulator of cognitive abilities. The consensus in the literature is that people with an intellectual disability perform significantly lower on executive function tasks than groups matched on chronological age. The comparison with groups matched on mental age is less clear. Therefore, the objective of this meta-analysis was to investigate to what extent executive function is impaired in people with intellectual disability compared with a typically developing control group matched on mental age. It was also investigated if the executive function component and intellectual disability aetiology moderated the effect.

METHODS

Eligibility criteria were participants with intellectual disability (IQ ≤ 75) without a dual diagnosis; a comparison group matched on mental age; executive function outcome reported in a group comparison study design with n ≥ 10. Working memory tasks and ratings of executive function were not included. The literature search yielded 6637 potentially interesting articles. Twenty-six studies (with 99 effect sizes) including 1395 participants were included in the quantitative synthesis.

RESULTS

A multilevel random-effects meta-analysis found that people with intellectual disability performed statistically significantly lower than the mental age-matched group on the executive function tasks, g = -0.34, 95% confidence interval = [-0.53, -0.16]. However, the heterogeneity between effect sizes was large. The intellectual disability aetiology moderator was significant, but it only reduced the heterogeneity marginally.

CONCLUSION

The overall conclusion is that individuals with an intellectual disability have more problems with executive function tasks than mental age-matched controls. Limitations are the large unexplained variance and the remarkably high number (69) of different tests that were used, which make more detailed conclusions problematic. This meta-analysis implies that future studies need to be of better quality, to have higher power, and to a higher degree use the same executive function tests.

Executive functions and their relationship with intellectual capacity and age in schoolchildren with intellectual disability

BACKGROUND

There is certain empirical evidence of, on the one hand, a positive correlation between executive functions (EFs) and intelligence in people with intellectual disability (ID) and, on the other hand, a slower rate of development of EFs in these people relative to people without ID. This evidence is not, however, unequivocal, and further studies are required.

METHODS

We analysed the relationship between development of EFs and both age and intellectual capacity, in a sample of 106 students with either ID or borderline intellectual functioning (BIF) at a special education centre [63 boys and 43 girls, 11-18 years old, mean total intelligence quotient (TIQ) of 59.6]. We applied nine instruments to evaluate both neuropsychological development (working memory, inhibitory control, cognitive flexibility, planning, processing speed and verbal fluency) and behavioural development [teachers' perceptions of the EFs of their students by Behavior Rating Inventory of Executive Function - Second Edition (BRIEF-2) School]. ID and BIF groups were statistically compared in terms of mean performance measures in EF tests. We looked at the correlation between EFs and age, and correlations between EFs and intelligence: TIQ, fluid intelligence [measured by the perceptual reasoning (PR) sub-index of Wechsler Intelligence Scale for Children-IV (WISC-IV)] and crystallised intelligence (measured by the verbal comprehension (VC) sub-index of WISC-IV). Regression models were built for variables with strong correlation.

RESULTS

In most of the tests used to evaluate EFs, the ID subgroup performed significantly worse than the subgroup with BIF. In general, teachers' thought that participants had 'medium-low' levels of EFs. TIQ, by WISC-IV scale, correlated significantly with scores in all tests for all EFs. The PR sub-index correlated significantly with 14 of the tests for EFs; 35% of the variation in PR can be explained by variation in performance in Picture Span (working memory) and Mazes (planning). The VC sub-index correlated weakly with seven of the EF tests. We found significant correlations in the ID group between age and scores in all tests of working memory and inhibitory control. Age - considering all participants - did not correlate with any of the variables of teachers' perception except for working memory, and this correlation was not strong.

CONCLUSIONS

The results of our study are consistent with descriptions of the typical population: (1) fluid intelligence is more related to EFs than crystallised intelligence is; and (2) working memory capacity is the EF most strongly related with general, fluid and crystallised forms of intelligence. The results suggest that as children and adolescents with ID/BIF get older, their capacities for working memory and inhibitory control increase; development of the other EFs studied was less evident. Teachers' perceptions of the EFs of children with ID or BIF were independent of intellectual capacity and age. More research is needed to delve further into the development of EFs in people with ID/BIF.

Executive Functioning in Adults with Down Syndrome: Machine-Learning-Based Prediction of Inhibitory Capacity

The study of executive function decline in adults with Down syndrome (DS) is important, because it supports independent functioning in real-world settings. Inhibitory control is posited to be essential for self-regulation and adaptation to daily life activities. However, cognitive domains that most predict the capacity for inhibition in adults with DS have not been identified. The aim of this study was to identify cognitive domains that predict the capacity for inhibition, using novel data-driven techniques in a sample of adults with DS (n = 188; 49.47% men; 33.6 ± 8.8 years old), with low and moderate levels of intellectual disability. Neuropsychological tests, including assessment of memory, attention, language, executive functions, and praxis, were submitted to Random Forest, support vector machine, and logistic regression algorithms for the purpose of predicting inhibition capacity, assessed with the Cats-and-Dogs test. Convergent results from the three algorithms show that the best predictors for inhibition capacity were constructive praxis, verbal memory, immediate memory, planning, and written verbal comprehension. These results suggest the minimum set of neuropsychological assessments and potential intervention targets for individuals with DS and ID, which may optimize potential for independent living.

Study of the deficit in planning abilities of adults with Prader-Willi Syndrome

BACKGROUND

Prader-Willi syndrome (PWS) is a complex developmental genetic disorder associated with intellectual disability and deficits in executive functions which result in disorganisation and poor personal autonomy.

AIMS

This study aimed to determine impairments in planning skills of adults with PWS, in relation with their intellectual disabilities, as well as the influence of food compulsions on their performance.

METHODS AND PROCEDURES

A modified version of the Zoo Map from the Behavioural Assessment of the Dysexecutive Syndrome was used in three groups: a group of adults with PWS in comparison with two groups both matched on chronological age, one with typical development (TD) and one with intellectual disability (ID).

OUTCOMES AND RESULTS

Compared to TD adults, both adults with PWS and ID showed increased planning time and lower raw scores on the planning task. The execution time and the number of errors were higher in the PWS group compared to the comparison groups. All three groups performed worse in the non-food condition only for number of errors and raw score.

CONCLUSIONS AND IMPLICATIONS

Planning abilities were impaired in PWS adults. Results also showed that intellectual level plays a role in participants' performance. These findings are essential to understand the difficulties of people with PWS daily life.

Decoding Abilities in Adolescents with Intellectual Disabilities: The Contribution of Cognition, Language, and Home Literacy

Decoding abilities in individuals with intellectual disabilities (ID) are substantially lower than for typical readers. The underlying mechanisms of their poor reading remain uncertain. The aim of this study was to investigate the concurrent predictors of decoding ability in 136 adolescents with non-specific ID, and to evaluate the results in relation to previous findings on typical readers. The study included a broad range of cognitive and language measures as predictors of decoding ability. A LASSO regression analysis identified phonological awareness and rapid automatized naming (RAN) as the most important predictors. The predictors explained 57.73% of the variance in decoding abilities. These variables are similar to the ones found in earlier research on typically developing children, hence supporting our hypothesis of a delayed rather than a different reading profile. These results lend some support to the use of interventions and reading instructions, originally developed for typically developing children, for children and adolescents with non-specific ID.

Investigating Reading Comprehension in Adolescents with Intellectual Disabilities: Evaluating the Simple View of Reading

Reading comprehension difficulties are common in individuals with intellectual disabilities (ID), but the influences of underlying abilities related to reading comprehension in this group have rarely been investigated. One aim of this study was to investigate the Simple View of Reading as a theoretical framework to describe cognitive and linguistic abilities predicting individual differences in reading comprehension in adolescents with non-specific ID. A second aim was to investigate whether predictors of listening comprehension and reading comprehension suggest that individuals with ID have a delayed pattern of development (copying early grade variance in reading comprehension) or a different pattern of development involving a new or an unusual pattern of cognitive and linguistic predictors. A sample of 136 adolescents with non-specific ID was assessed on reading comprehension, decoding, linguistic, and cognitive measures. The hypotheses were evaluated using structural equation models. The results showed that the Simple View of Reading was not applicable in explaining reading comprehension in this group, however, the concurrent predictors of comprehension (vocabulary and phonological executive-loaded working memory) followed a delayed profile.

Procedural Learning through Action Observation: Preliminary Evidence from Virtual Gardening Activity in Intellectual Disability

Intellectual disability (ID) compromises intellectual and adaptive functioning. People with an ID show difficulty with procedural skills, with loss of autonomy in daily life. From an embodiment perspective, observation of action promotes motor skill learning. Among promising technologies, virtual reality (VR) offers the possibility of engaging the sensorimotor system, thus, improving cognitive functions and adaptive capacities. Indeed, VR can be used as sensorimotor feedback, which enhances procedural learning. In the present study, fourteen subjects with an ID underwent progressive steps training combined with VR aimed at learning gardening procedures. All participants were trained twice a week for fourteen weeks (total 28 sessions). Participants were first recorded while sowing zucchini, then they were asked to observe a virtual video which showed the correct procedure. Next, they were presented with their previous recordings, and they were asked to pay attention and to comment on the errors made. At the end of the treatment, the results showed that all participants were able to correctly garden in a real environment. Interestingly, action observation facilitated, not only procedural skills, but also specific cognitive abilities. This evidence emphasizes, for the first time, that action observation combined with VR improves procedural learning in ID.

Executive Functions and Attention Processes in Adolescents and Young Adults with Intellectual Disability

(1) Background: We made a comprehensive evaluation of executive functions (EFs) and attention processes in a group of adolescents and young adults with mild intellectual disability (ID). (2) Methods: 27 adolescents and young adults (14 females and 13 males) with ID, aged between 15.1 and 23 years (M = 17.4; SD = 2.04), were compared to a control group free of cognitive problems and individually matched for gender and age. (3) Results: As for EFs, individuals with ID were severely impaired on all subtests of the Behavioral Assessment of Dysexecutive Syndrome (BADS) battery. However, we also found appreciable individual differences, with eight individuals (approximately 30%) scoring within normal limits. On the attention tests, individuals with ID were not generally slower but presented specific deficits only on some attention tests (i.e., Choice Reaction Times, Color Naming and Color–Word Interference, and Shifting of Attention for Verbal and for Visual Targets).The role of a global factor (i.e., cognitive speed) was modest in contributing to the group differences; i.e., when present, group differences were selectively associated with specific task manipulations, not global differences in cognitive speed. (4) Conclusions: The study confirmed large group differences in EFs; deficits in attentional processing were more specific and occurred primarily in tasks taxing the selective dimension of attention, with performance on intensive tasks almost entirely spared.

Effects of running exercises on reaction time and working memory in individuals with intellectual disability

BACKGROUND

This study explored the effect of running exercises at low [30% heart rate reserve (HRR)] and moderate (60%HRR) intensities on cognitive performances in individuals with intellectual disability (ID).

METHODS

Participants performed randomly reaction time (RT) tests: visual RT [simple RT (SRT) and choice RT (CRT)], auditory SRT (ASRT) and working memory (WM) (Corsi test) before and after the exercises.

RESULTS

The results showed that after both exercises, SRT decreased significantly (P < 0.001) in both groups with higher extent (P < 0.05) at 60%HRR compared with 30%HRR. CRT decreased (P < 0.01), similarly, after the both exercises in both groups with higher (P < 0.001) extent in the intellectual disability group (IDG). ASRT decreased significantly, at 30%HRR, in IDG (P < 0.001) and in control group (CG) (P < 0.01) with greater extent in IDG (P < 0.001). At 60%HRR, ASRT decreased significantly in both groups (P < 0.001) with greater extent in IDG (P < 0.001). The ΔASRT% was significantly (P < 0.05) higher at 30%HRR compared with 60%HRR in IDG. In CG, no significant (P = 0.21) difference was reported between intensities. The Corsi forward and the Corsi backward scores increased significantly (P < 0.01) in both groups after both intensities with higher extent in IDG (P < 0.01).

CONCLUSIONS

Our results suggest that low and moderate running exercises improve similarly simple and choice visual RT as well as WM in individuals with ID. Furthermore, low-intensity exercise could be more appropriate to enhance ASRT compared the moderate one in these individuals. Therefore, low-intensity exercise seems to be an efficient strategy to improve cognitive performances in individuals with ID.

Similarities and Differences Between Youth Who Engaged in Intrafamilial and Extrafamilial Sexually Abusive Behavior: An Exploratory Study

This study examined differences between youth who engaged in intrafamilial (ISAB) and extrafamilial sexually abusive behavior (ESAB) on various characteristics covering the sociodemographic, offense-related, psychological, and environmental domains. A total of 85 Dutch male youth participated in this study. Information was obtained through self-report questionnaires and systematic screening of the case files. Youth who engaged in ISAB, compared with ESAB, came from larger families, were enrolled in higher levels of secondary education and started sexual offending at a younger age. Youth who engaged in ESAB were more frequently diagnosed with attention-deficit hyperactivity disorder (ADHD) and intellectual disabilities (ID) and primarily received longer treatment in the context of residential care. The findings are discussed in connection to the literature on (adult) sexual offending. The risk factors and criminogenic needs that distinguish youth who engaged in ISAB and ESAB appear different from those found in adult populations.

Participation Difficulties in Autism Spectrum Disorders and Intellectual Disabilities: Findings from the 2011 Survey of Pathway to Diagnosis and Services

Greater understanding can increase our knowledge and intervention effectiveness for activity participation problems of children with disabilities. We examined participation difficulties of children with autism spectrum disorders (ASD) and intellectual disabilities (ID) in the 2011 Survey of Pathway to Diagnosis and Services. We utilized propensity score matching with inverse probability of treatment weight with questions from parents of 1783 children aged 6-17 years. Friendship was the most difficult area for all children. Children with both ASD and ID experienced the most difficulty in all areas, followed by ASD alone. Reported levels of home life, friendships, classroom and leisure difficulties were moderately correlated for all children. Children who were previously diagnosed, but have no current diagnosis experienced substantial difficulties.

Functioning of Cognitive Memory Inhibition Processes in People with Down Syndrome: An Empirical Study

Cognitive inhibition is part of executive functions. When it exercises control over memory processes, it has the function of regulating the accessibility of memories and allows interference to be resolved. The impairment of its functioning has been related to the presence of forgetfulness of relevant information. In this research, we study the functioning of cognitive memory inhibition processes in people with intellectual disabilities in tasks of delayed visual recognition and analyze the influence of age. For this purpose, 36 people with Down syndrome (mean age = 33.44, standard deviation = 7.54, 50% females) and 36 people with neurotypical development (mean age = 33.55, standard deviation = 7.52, 50% females) participated. The results reflected a lower effectiveness in the group of people with Down syndrome, F(1, 68) = 159.09, p < .001, $ {\upeta}_{\mathrm{p}}^2 $ = .70. The people in the group with Down syndrome had difficulties in interference resolution, both in the subgroup of young people (p = .014, $ \hat{\updelta\ } $= 0.88) and in the subgroup of older people (p = .022, $ \hat{\updelta\ } $= 0.67). The impairment of cognitive inhibition in people with Down syndrome warrants the need to develop specific intervention programs for this process.

Cognitive abilities and life experience in everyday planning in adolescents with intellectual disabilities: Support for the difference model

BACKGROUND

The literature on planning ability in individuals with intellectual disability (ID) provides no clarity on whether their ability matches their mental age (MA) or not. Perhaps can planning experience explain the mixed results. The current study investigated to what extent cognitive abilities and life experience can explain everyday planning ability in individuals with ID and to what extent results from everyday planning tasks support the developmental or the difference model of ID.

METHOD

Planning tests, cognitive ability tasks and a self-rated life experience form were administered to 71 adolescents with ID and 62 children with a typical development matched on MA.

RESULTS

Adolescents with ID exhibited planning ability according to their MA. Regression analyses showed that the predictors of planning differed between the groups. The cognitive measures could predict planning in both groups, but life experience only contributed positively to planning in the MA group, whereas chronological age was negatively correlated with successful planning in the ID group.

CONCLUSIONS AND DISCUSSION

The results support the difference model of ID. When matched on MA, the individuals with ID will solve the planning task in a qualitatively different manner. Additionally, the participants with ID could not utilise their life experience when solving the planning task, contrary to the MA group. Practitioners should be aware that individuals with ID might need more everyday planning training throughout adolescence. To support adolescents with ID, practitioners may focus on supporting the individual's cognitive abilities rather than relying on their prior knowledge.

Cognitive Mediators of School-Related Socio-Adaptive Behaviors in ASD and Intellectual Disability Pre- and Adolescents: A Pilot-Study in French Special Education Classrooms

The school inclusion of students with autism is still a challenge. To address the cognitive underpinnings of school-related adaptive behaviors, 27 students with autism and 18 students with intellectual and/or severe learning disability, aged from 11 to 17, were recruited. They underwent socio-emotional processing and executive functioning assessments, as well as school-related adaptive behavior and quality of life measurements. Both groups performed equally on socio-emotional and executive assessments, and they reported the same low quality of life. However, students with autism exhibited more limitations than the students with intellectual disabilities on complex school adaptive behaviors (socialization and autonomy) and problem behaviors, but both groups performed equally on more basic adaptive behaviors (school routines, communication). Multiple regression analyses highlighted between-group differences in terms of adaptive functioning profiles, which were linked with different cognitive predictors according to students’ medical conditions. The greater school-related limitations of students with autism were mostly explained by socio-emotional performance, while IQ (intellectual quotient) mostly explained the comparable between-group limitations. The low quality of life of both groups was slightly explained by executive performance. The role of both socio-emotional and executive functioning in students’ adaptive behaviors and quality of life suggests remediation targets for promoting the school inclusion of students with autism.

Visual search strategies in a shared zone in pedestrians with and without intellectual disability

People with intellectual disability (ID) may find shared zones troublesome to negotiate because of the lack of the traditional clearly defined rules and boundaries. With the built environment identified as a barrier to active travel and community access, it is vital to explore how pedestrians with ID navigate shared zones to ensure that this group is not placed in harm's way or discouraged from active travel because of the implications of shared zones. This study investigated the visual strategies of 19 adults with ID and 21 controls who wore head mounted eye trackers in a Shared Zone and at a zebra crossing (as a contrast traffic environment). In total 4750 valid fixations were analysed. Participants with ID fixated on traffic relevant objects at a rate of 68 percent of the control participants. Furthermore, the males with ID were 9(4.4-18.7) times more likely to fixate on non-traffic relevant objects compared with traffic relevant objects, much higher odds than that of females with ID 1.8(0.4-1.7). Zebra crossings appeared to act as a cue, drawing pedestrians' visual attention to the traffic environment, with both groups more likely to look at traffic relevant objects on/at the zebra crossing (66%: 34%). Future implementation of shared zones needs to be carefully considered in relation to the safety of road users with ID and their capacity to identify and assess salient environmental information.

Competencies for rating perceived exertion in amateur soccer players with and without intellectual disabilities

BACKGROUND

Perception of exertion is essential for self-regulation in sports. The ability to rate perceived exertion (RPE) is regarded as psychophysiological competence, although cognitive components of RPE are largely unknown. The present study tested the hypothesis that cognitive processing speed, perseveration and figural fluency correlate with RPE.

METHODS

The present study tested relationships between the performance in neuropsychological tests and the competence for RPE assessed during soccer training in 30 adults with and 22 adults without intellectual disabilities.

RESULTS

Mean correlation coefficients for RPE and heart rate differed significantly between participants with intellectual disabilities (r = .41) and participants without intellectual disabilities (r = .71). The variance of RPE could be partially explained by neuropsychological performance measures reflecting cognitive processing speed and perseveration and by age.

CONCLUSIONS

The results point to an impaired perception of exertion in people with intellectual disabilities, which can be partially explained by individual neuropsychological competencies.

Description of Routes in People With Intellectual Disability

The ability to describe routes was assessed in participants with intellectual disability (ID) and participants without ID matched on chronological age (CA) or on mental age (MA). In two experiments, participants learned a route through a virtual environment until they reached a learning criterion. They were then asked to externalize their spatial knowledge in a verbal description task, a landmark recognition task, or a map completion task. Results revealed that participants with ID mainly described the route as a succession of actions ("turn left"), and participants in the CA group prescribed actions referring to a landmark ("turn left at the swing"). Yet, results from the other tasks showed that people with ID had good landmark knowledge of the environment.

Verbal Working Memory Processes in Students With Mild and Borderline Intellectual Disabilities: Differential Developmental Trajectories for Rehearsal and Redintegration

In verbal working memory, two processes serve to retain a fading memory trace: subvocal rehearsal and lexical redintegration. While recent studies on students with mild and borderline intellectual disabilities (MBID) have yielded mixed results on rehearsal, redintegration has not been researched in MBID, yet. Furthermore, most studies have used a group-matched design which, due to methodological constraints, can only distinguish between two different development patterns. Thus, we study both rehearsal and redintegration in students with MBID using developmental trajectories that have greater potential for identifying differential developmental patterns than traditional group-matching approaches. We investigate whether three aspects in working memory develop differently in students with MBID in comparison to typically developing students: (a) the general capacity of the phonological loop, and the effectiveness of (b) rehearsal, and (c) redintegration. We use three different developmental indicators to compare trajectories: chronological age, cognitive capacity, and vocabulary size. N = 210 students (87 students with MBID, 123 typically developing students) completed working memory span tasks with short and long (1- vs. 3-syllable) real words and pseudowords. The effect for word length (short vs. long) measures rehearsal, and the lexicality effect (real words vs. pseudowords) measures redintegration. Results show that developmental trajectories reveal an intercept difference but no slowed rate in rehearsal, and no impairment in redintegration. However, concerning the developmental relation between redintegration and vocabulary size, students with MBID reveal a differential pattern as redintegration appears higher for students with small vocabulary size, but unexpectedly decreases as vocabulary size increases. We conclude that students with MBID show a delayed onset in the development of capacity of the phonological loop and rehearsal and that they do not catch up in their development. Redintegration does not seem to be impaired in relation to age and cognitive capacity. However, the differential relation of redintegration with vocabulary size calls for further research. While impaired subvocal rehearsal appears to be connected to the developmental problems of students with MBID, lexical redintegration seems to be intact in relation to chronological age and cognitive capacity, making it a possible area of strength.

Inhibition, shifting and updating in relation to psychometric intelligence across ability groups in the psychiatric population

BACKGROUND

Assessment of intelligence and executive function (EF) is common in complex neuropsychiatric practice. Although previous studies have shown that EF and intelligence are related, it is unknown whether these constructs relate to one another in a similar manner across different ability groups (mild intellectual disability, borderline intellectual disability and normal/high intelligence). This study therefore examines the relation between three EFs (inhibition, shifting and updating) and intelligence in a heterogeneous psychiatric sample. It is hypothesised that the strength of the relation between intelligence and the three EFs decreases when the level of intelligence increases, in accordance with Spearman's Law of Diminishing Returns.

METHODS

In a cross-sectional, between and within subject design, one of the three intelligence tests (Kaufman Adolescent and Adult Intelligence Test and Wechsler Adult Intelligence Scale - third and fourth editions) and several EF tests (Stroop Colour-Word Test, Trail Making Test and Spatial Working Memory task) were administered to 250 neuropsychiatric inpatients and outpatients (Mage  = 39.8, standard deviation = 14.3, 52.8% male). Based upon their full-scale IQ score, patients were divided into three ability groups (mild intellectual disability, borderline intellectual disability or normal/high intelligence). The relation between EF and intelligence was assessed through analyses of the correlation pattern; groups were compared using analysis of covariance.

RESULTS

Analyses showed significant correlations between the constructs of EF and intelligence. A significant interaction effect was found for shifting, with highest correlations in the normal to high intelligence group, but not for inhibition and updating.

CONCLUSIONS

Results support a specific role for shifting in this EF-intelligence relation. The correlational pattern of updating and intelligence, as well as the differential relation of shifting and intelligence across ability groups, suggests that EF tasks may not measure distinct EFs in lower intellectual ability but rely on cognitive primitives such as processing speed. EF tasks can be considered less valid indicators of EF ability. Implications in terms of the need for development of specific tasks to measure cognition in low intellectual ability are discussed.

Risk Assessment of Adolescents with Intellectual Disabilities Who Exhibit Sexual Behavior Problems or Sexual Offending Behavior

Adolescents with intellectual disabilities are known to engage in various sexual behavior problems or sexual offending behaviors. This article provides a review of important aspects of risk assessment within the context of a broader, more comprehensive and holistic assessment of these individuals. Pertinent risk and sexual interest assessment tools are identified along with their strengths and limitations. Issues that are often unattended to are addressed, including consideration of the behavioral implications of the young person's diagnosis and level of cognitive functioning, need for sexual knowledge and sexual interest assessment, and issues related to making a mental health diagnosis. Recommendations for future research are also offered.

Computer-based cognitive remediation program for the treatment of behavioral problems in children with intellectual disability: the «COGNITUS & MOI» study protocol for a randomized controlled trial

BACKGROUND

Comorbid psychiatric disorders are frequent in children with intellectual disability (ID). Given the limitations of drugs treatments, cognitive remediation could be a promising tool to reduce these challenging behaviors but evidence is still scarce. Our group recently developed the «COGNITUS & MOI» program that is designed to train the attentional and visuospatial skills in children with ID. This study investigates the efficiency of the «COGNITUS & MOI» program in this condition.

METHODS

Children (age: 6.00-13.11) with mild to moderate ID and behavioral problems, will benefit from a therapy during a 16 week randomized controlled trial. One group will be randomly treated with the «COGNITUS & MOI» program and the other with a motor skill and video viewing intervention. All participants will undergo a behavioral, functional and neurocognitive assessment at baseline, post-intervention, and 6-month follow-up. Primary outcome will be the change from the baseline of the score on the "hyperactivity - noncompliance" subscale of the Aberrant Behavior Checklist.

DISCUSSION

If the results are conclusive, the «COGNITUS & MOI» program could be added to the therapeutic arsenal against challenging behavior in children with ID.

TRIAL REGISTRATION

ClinicalTrials NCT02797418 . Date registered: 8th of June 2016.

Critical reappraisal of mechanistic links of copy number variants to dimensional constructs of neuropsychiatric disorders in mouse models

Copy number variants are deletions and duplications of a few thousand to million base pairs and are associated with extraordinarily high levels of autism spectrum disorder, schizophrenia, intellectual disability, or attention-deficit hyperactivity disorder. The unprecedented levels of robust and reproducible penetrance of copy number variants make them one of the most promising and reliable entry points to delve into the mechanistic bases of many mental disorders. However, the precise mechanistic bases of these associations still remain elusive in humans due to the many genes encoded in each copy number variant and the diverse associated phenotypic features. Genetically engineered mice have provided a technical means to ascertain precise genetic mechanisms of association between copy number variants and dimensional aspects of mental illnesses. Molecular, cellular, and neuronal phenotypes can be detected as potential mechanistic substrates for various behavioral constructs of mental illnesses. However, mouse models come with many technical pitfalls. Genetic background is not well controlled in many mouse models, leading to rather obvious interpretative issues. Dose alterations of many copy number variants and single genes within copy number variants result in some molecular, cellular, and neuronal phenotypes without a behavioral phenotype or with a behavioral phenotype opposite to what is seen in humans. In this review, I discuss technical and interpretative pitfalls of mouse models of copy number variants and highlight well-controlled studies to suggest potential neuronal mechanisms of dimensional aspects of mental illnesses. Mouse models of copy number variants represent toeholds to achieve a better understanding of the mechanistic bases of dimensions of neuropsychiatric disorders and thus for development of mechanism-based therapeutic options in humans.

Basal ganglia involvement in ARX patients: The reason for ARX patients very specific grasping?

The ARX (Aristaless Related homeoboX) gene was identified in 2002 as responsible for XLAG syndrome, a lissencephaly characterized by an almost complete absence of cortical GABAergic interneurons, and for milder forms of X-linked Intellectual Disability (ID) without apparent brain abnormalities. The most frequent mutation found in the ARX gene, a duplication of 24 base pairs (c.429_452dup24) in exon 2, results in a recognizable syndrome in which patients present ID without primary motor impairment, but with a very specific upper limb distal motor apraxia associated with a pathognomonic hand-grip, described as developmental Limb Kinetic Apraxia (LKA).

In this study, we first present ARX expression during human fetal brain development showing that it is strongly expressed in GABAergic neuronal progenitors during the second and third trimester of pregnancy. We show that although ARX expression strongly decreases towards the end of gestation, it is still present after birth in some neurons of the basal ganglia, thalamus and cerebral cortex, suggesting that ARX also plays a role in more mature neuron functioning. Then, using morphometric brain MRI in 13 ARX patients carrying c.429_452dup24 mutation and in 13 sex- and age-matched healthy controls, we show that ARX patients have a significantly decreased volume of several brain structures including the striatum (and more specifically the caudate nucleus), hippocampus and thalamus as well as decreased precentral gyrus cortical thickness. We observe a significant correlation between caudate nucleus volume reduction and motor impairment severity quantified by kinematic parameter of precision grip.

As basal ganglia are known to regulate sensorimotor processing and are involved in the control of precision gripping, the combined decrease in cortical thickness of primary motor cortex and basal ganglia volume in ARX dup24 patients is very likely the anatomical substrate of this developmental form of LKA.

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c.429_452dup24 in ARX is responsible for ID with Limb Kinetic Apraxia.

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During human brain development, ARX is expressed in GABAergic neuronal progenitors.

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ARX patients have a significantly decreased caudate nucleus volume by MRI.

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This caudate nucleus volume reduction is correlated with motor impairment severity.

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These anatomic findings may explain this developmental form of Limb Kinetic Apraxia.

Copy number elevation of 22q11.2 genes arrests the developmental maturation of working memory capacity and adult hippocampal neurogenesis

Working memory capacity, a critical component of executive function, expands developmentally from childhood through adulthood. Anomalies in this developmental process are seen in individuals with autism spectrum disorder (ASD), schizophrenia and intellectual disabilities (ID), implicating this atypical process in the trajectory of developmental neuropsychiatric disorders. However, the cellular and neuronal substrates underlying this process are not understood. Duplication and triplication of copy number variants of 22q11.2 are consistently and robustly associated with cognitive deficits of ASD and ID in humans, and overexpression of small 22q11.2 segments recapitulates dimensional aspects of developmental neuropsychiatric disorders in mice. We capitalized on these two lines of evidence to delve into the cellular substrates for this atypical development of working memory. Using a region- and cell-type-selective gene expression approach, we demonstrated that copy number elevations of catechol-O-methyl-transferase (COMT) or Tbx1, two genes encoded in the two small 22q11.2 segments, in adult neural stem/progenitor cells in the hippocampus prevents the developmental maturation of working memory capacity in mice. Moreover, copy number elevations of COMT or Tbx1 reduced the proliferation of adult neural stem/progenitor cells in a cell-autonomous manner in vitro and migration of their progenies in the hippocampus granular layer in vivo. Our data provide evidence for the novel hypothesis that copy number elevations of these 22q11.2 genes alter the developmental trajectory of working memory capacity via suboptimal adult neurogenesis in the hippocampus.

Impact of Attention Training on Academic Achievement, Executive Functioning, and Behavior: A Randomized Controlled Trial

Children with intellectual and developmental disabilities (IDD) experience significant difficulties in attention, learning, executive functions, and behavioral regulation. Emerging evidence suggests that computerized cognitive training may remediate these impairments. In a double blind controlled trial, 76 children with IDD (4-11 years) were randomized to either an attention training (n = 38) or control program (n = 38). Both programs were completed at home over a 5-week period. Outcome measures assessed literacy, numeracy, executive functioning, and behavioral/emotional problems, and were conducted at baseline, post-training, and 3-month follow-up. No training effects were observed at post-training; however, children in the training group showed greater improvements in numeracy skills at the 3-month follow-up. These results suggest that attention training may be beneficial for children with IDD; however, the modest nature of the intervention effects indicate that caution should be taken when interpreting clinical significance.

Working memory studies among individuals with intellectual disability: An integrative research review

BACKGROUND

Integrative research review infers generalizations about a substantive subject, summarizes the accumulated knowledge that research has left unresolved and generates a new framework on these issues. Due to methodological issues emerging from working memory (WM) studies in the population with non-specific intellectual disability (NSID) (N=64) between 1990-2014, it is difficult to conclude on WM performance in this population.

AIM

This integrative research review aimed to resolve literature conflicts on WM performance among individuals with NSID and to identify the conditions/moderators that govern their WM performance compared to controls with Typical development.

METHOD/PROCEDURE

We used the six stages of integrative research review: problem formulation, data collection, evaluation, data analysis, results, interpretation and discussion.

OUTCOMES AND RESULTS

The findings indicate two types of moderators that determine WM performance in the population with NSID: Participants' moderators (criteria for matching the ID and TD groups, CA and MA), and task moderators [the three WM components of Baddeley and Hitch's (1974) model and task load]. Only an interaction between the two moderators determines WM performance in this population. The findings indicate a hierarchy (from more to less preserved) in WM performance of individuals with NSID: The visuospatial tasks, then some of the executive functions tasks, and the phonological loop tasks being less preserved. Furthermore, at a low level of control, the performance of participants with NSID was preserved beyond the modality and vice versa.

CONCLUSIONS AND IMPLICATIONS

Modality and MA/intelligence determine WM performance of individuals with ID. Educators should prepare intervention programs take the impact of the two moderators into account.

Training on Working Memory and Inhibitory Control in Young Adults

Different types of interventions have focused on trying to improve Executive Functions (EFs) due to their essential role in human cognition and behavior regulation. Although EFs are thought to be diverse, most training studies have targeted cognitive processes related to working memory (WM), and fewer have focused on training other control mechanisms, such as inhibitory control (IC). In the present study, we aimed to investigate the differential impact of training WM and IC as compared with control conditions performing non-executive control activities. Young adults were divided into two training (WM/IC) and two (active/passive) control conditions. Over six sessions, the training groups engaged in three different computer-based adaptive activities (WM or IC), whereas the active control group completed a program with low control-demanding activities that mainly involved processing speed. In addition, motivation and engagement were monitored through the training. The WM-training activities required maintenance, updating and memory search processes, while those from the IC group engaged response inhibition and interference control. All participants were pre- and post-tested in criterion tasks (n-back and Stroop), near transfer measures of WM (Operation Span) and IC (Stop-Signal). Non-trained far transfer outcome measures included an abstract reasoning test (Raven’s Advanced Progressive Matrices) and a well-validated experimental task (AX-CPT) that provides indices of cognitive flexibility considering proactive/reactive control. Training results revealed that strongly motivated participants reached higher levels of training improvements. Regarding transfer effects, results showed specific patterns of near transfer effects depending on the type of training. Interestingly, it was only the IC training group that showed far transfer to reasoning. Finally, all trained participants showed a shift toward a more proactive mode of cognitive control, highlighting a general effect of training on cognitive flexibility. The present results reveal specific and general modulations of executive control mechanisms after brief training intervention targeting either WM or IC.

The impact of behavioural executive functioning and intelligence on math abilities in children with intellectual disabilities

BACKGROUND

Little is known about the role of behavioural executive functioning (EF) skills and level of intelligence (IQ) on math abilities in children with mild to borderline intellectual disabilities.

METHOD

Teachers of 63 children attending a school for special education (age: 10 to 13 years; IQ: 50 to 85) filled out a Behaviour Rating Inventory for Executive Function for each student. Furthermore, students took a standardised national composite math test and a specific math test on measurement and time problems. Information on level of intelligence was gathered through school records. Multiple regression analyses were performed to test direct, moderating and mediating effects of EF and IQ on math performance.

RESULTS

Behavioural problems with working memory and flexibility had a direct negative effect on math outcome, while concurrently, level of intelligence had a positive effect. The effect of IQ on math skills was moderated by problems with inhibition: in children with a clinical level of inhibition problems, there was no effect of level of intelligence on math performance.

CONCLUSIONS

Findings suggest that in students with mild to borderline intellectual disabilities and math difficulties, it is important to address their strengths and weaknesses with respect to EF and adjust instruction and remedial intervention accordingly.

The Role of Executive Control and Readiness to Change in Problematic Drinkers with Mild to Borderline Intellectual Disability

BACKGROUND

Problematic alcohol use is associated with neuropsychological consequences, including cognitive biases. The goal of the study was to explore the moderating role of executive control and readiness to change on the relationship between alcohol use and cognitive biases in light and problematic drinkers with and without mild to borderline intellectual disability (MBID).

METHOD

Participants (N = 112) performed the visual dot probe task to measure the strength of the cognitive biases. Executive control was measured using two computerised tasks for working memory capacity (Corsi block-tapping task) and inhibitory control (Go/No-go task). Readiness to change was measured using the Readiness to Change Questionnaire.

RESULTS

No cognitive biases or executive dysfunctions were found in problematic drinkers. Working memory capacity and inhibitory control were impaired among individuals with MBID, irrespective of severity of alcohol use-related problems. Executive control and readiness to change did not moderate the relationship between alcohol use and cognitive biases.

CONCLUSION

The results fail to support the dual-process models of addiction, but results need to be treated with caution given the problematic psychometric qualities of the visual dot probe task. Implementing a neurocognitive assessment and protocols in the treatment of substance use disorders seems premature.

Gestural praxis in young adults with mild to moderate intellectual disabilities

BACKGROUND

Praxis functioning in the population with intellectual disabilities (ID) has been poorly studied. The goal of this research was to look for a starting point to study the praxic functioning in young adults with mild to moderate ID.

METHOD

Thirty young adults with ID and 30 young adults without ID, between the ages of 18 and 35 years, participated in this study. All participants completed tests that assessed gestural praxis.

RESULTS

It was possible to observe similar praxis behaviour in the group with ID in almost all domains studied, albeit showing statistical values lower than those of the group without ID.

DISCUSSIONS

Despite the high number of errors committed, the sample of participants with ID was able to reach the goal of praxic tasks performed; such errors may be associated with a deficit in the development of various brain functions and not only with praxis functioning, mainly related to a lower yield in terms of planning, monitoring and correcting intentional movement.

A Novel Analog Reasoning Paradigm: New Insights in Intellectually Disabled Patients

Background

Intellectual Disability (ID) is characterized by deficits in intellectual functions such as reasoning, problem-solving, planning, abstract thinking, judgment, and learning. As new avenues are emerging for treatment of genetically determined ID (such as Down’s syndrome or Fragile X syndrome), it is necessary to identify objective reliable and sensitive outcome measures for use in clinical trials.

Objective

We developed a novel visual analogical reasoning paradigm, inspired by the Progressive Raven’s Matrices, but appropriate for Intellectually Disabled patients. This new paradigm assesses reasoning and inhibition abilities in ID patients.

Methods

We performed behavioural analyses for this task (with a reaction time and error rate analysis, Study 1) in 96 healthy controls (adults and typically developed children older than 4) and 41 genetically determined ID patients (Fragile X syndrome, Down syndrome and ARX mutated patients). In order to establish and quantify the cognitive strategies used to solve the task, we also performed an eye-tracking analysis (Study 2).

Results

Down syndrome, ARX and Fragile X patients were significantly slower and made significantly more errors than chronological age-matched healthy controls. The effect of inhibition on error rate was greater than the matrix complexity effect in ID patients, opposite to findings in adult healthy controls. Interestingly, ID patients were more impaired by inhibition than mental age-matched healthy controls, but not by the matrix complexity. Eye-tracking analysis made it possible to identify the strategy used by the participants to solve the task. Adult healthy controls used a matrix-based strategy, whereas ID patients used a response-based strategy. Furthermore, etiologic-specific reasoning differences were evidenced between ID patients groups.

Conclusion

We suggest that this paradigm, appropriate for ID patients and developmental populations as well as adult healthy controls, provides an objective and quantitative assessment of visual analogical reasoning and cognitive inhibition, enabling testing for the effect of pharmacological or behavioural intervention in these specific populations.

«Cognitus & Moi»: A Computer-Based Cognitive Remediation Program for Children with Intellectual Disability

Attentional, visuospatial, and social cognition deficits have a negative impact on children's adaptative and social competences and, as a result, on their ability to achieve a normal functioning and behavior. Until now and despite the frequency of those deficits, there is a lack of children's specific cognitive remediation tools specifically dedicated to attentional and visuospatial areas. The «Cognitus & Moi» program involves a variety of exercises in a paper and/or pencil (n = 30) or a computerized format (n = 29) and a strategy coaching approach. Each module of «Cognitus & Moi» targets a single impaired cognitive area, within the limits of cognitive domains' overlapping. The little cartoon character named Cognitus, who illustrates the program, is supposed to be very friendly and kind toward children. Cognitus will accompany them throughout the program for an effective and positive reinforcement. The main goal of «Cognitus & Moi» is to adjust to children's difficulties in daily life. Moreover, since the cognitive remediation benefit is complex to apply in daily life, the program is based on a metacognitive strategy. After a complete neuropsychological assessment and a psychoeducational session (with the child and the parents), 16 1-h-sessions of cognitive remediation with the therapist are proposed. Each session is composed of three parts: (1) computerized tasks focusing on specific attentional or visuospatial components (20 min). The attentional module targets hearing, visual, and divided attention. A double attention task is also proposed. The visuospatial module targets eye tracking and gaze direction, spatial orientation, visuospatial memory and construction, and mental imagery; (2) pen and paper tasks focusing on the same processes (20 min) and a facial emotion recognition task; (3) a proposal of a home-based task (during 20 min). Weekly, specific attentional and visuospatial home tasks are proposed to the child and analyzed with the parents and the therapist. Indeed, home exercises are useful to promote the transfer of strategies to daily life and their subsequent automation. The heterogeneity of cognitive deficits in intellectual deficiency necessitates an individualized cognitive remediation therapy. In this regard, «Cognitus & Moi» seems to be a promising tool.

Executive functioning in individuals with intellectual disabilities and autism spectrum disorders

BACKGROUND

Executive functioning (EF) is important for adequate behavioural functioning and crucial for explaining symptoms of autism spectrum disorders (ASD) in individuals with normal intelligence, but is scarcely studied in individuals with ASD and intellectual disabilities (ID). We therefore study EF in an ID population by comparing performances on three frequently studied executive functions (shifting, inhibition and updating) between individuals with ASD and individuals without ASD. When studying ID populations, one should be aware of Spearman's Law of Diminishing Returns (SLODR), as it questions the possibility of measuring separate cognitive functions in ID populations.

METHODS

Six EF tasks were administered to 50 individuals with mild to borderline ID, of which half was diagnosed with ASD. In order to investigate the distinctness of the three executive functions in this ID sample, the results on the six EF tasks were subjected to principal components analysis (PCA). Subsequently, a multivariate analysis of variance (MANOVA) was performed to assess differences between the ASD and non-ASD group on shifting, inhibition and updating.

RESULTS

The PCA revealed the hypothesised EF trichotomy. MANOVA analysis showed no significant group differences on EF-performance.

CONCLUSIONS

Three separate executive functions were measured in this ID population, but despite much evidence that individuals with ASD display more behavioural problems and the proven relevance of EF in behavioural functioning, no significant group difference was found on shifting, inhibition or updating. After this first effort to achieve more insight into EF of individuals with ASD and ID the relation between behavioural problems and EF will require further study.

The acquisition of contextual cueing effects by persons with and without intellectual disability

Two experiments were conducted to compare the acquisition of contextual cueing effects of adolescents and young adults with intellectual disabilities (ID) relative to typically developing children and young adults. Contextual cueing reflects an implicit, memory based attention guidance mechanism that results in faster search for target locations that have been previously experienced in a predictable context. In the study, participants located a target stimulus embedded in a context of numerous distracter stimuli. During a learning phase, the location of the target was predictable from the location of the distracters in the search displays. We then compared response times to locating predictable relative to unpredictable targets presented in a test phase. In Experiment 1, all of the distracters predicted the location of the target. In Experiment 2, half of the distracters predicted the location of the target while the other half varied randomly. The participants with ID exhibited significant contextual facilitation in both experiments, with the magnitude of facilitation being similar to that of the typically developing (TD) children and adults. We concluded that deficiencies in contextual cueing are not necessarily associated with low measured intelligence that results in a classification of ID.

Executive function in children with intellectual disability--the effects of sex, level and aetiology of intellectual disability

BACKGROUND

Executive function is very important in the children's overall development. The goal of this study was to assess the executive function in children with intellectual disability (ID) through the use of the Behavior Rating Inventory of Executive Function (BRIEF) teacher version. An additional goal was to examine the differences in executive function in relation to child's sex, level and aetiology of ID.

METHOD

The sample consisted of 90 children with ID attending two special education schools in Sarajevo, Bosnia and Herzegovina. There were 42 children with mild ID and 48 children with moderate ID. Of those, 54 were boys and 36 were girls. Children were classified into three etiological categories: 30 children with Down syndrome, 30 children with other genetic cause or organic brain injury and 30 children with unknown aetiology of ID. Special education teachers, who knew the children for at least 6 months filled the BRIEF.

RESULTS

Children with ID had a significant deficit in executive function as measured by the BRIEF. There were no statistically significant differences in executive function in relation to the child's sex. Level of ID had a significant effect on executive function. In relation to the aetiology of ID, the only significant difference was on the Shift scale of the BRIEF.

CONCLUSIONS

Knowing what executive function is most impaired in children with ID will help professionals design better intervention strategies. More attention needs to be given to the assessment of executive function and its subsequent intervention in the school settings.

[Theoretical and practical aspects of cognitive remediation in intellectual disabilities: Relevance of the Cognitive Remediation Therapy program (CRT)]

INTRODUCTION

Teenagers and adults with intellectual disabilities are nowadays "over-handicapped", often due to lack of care in self-sufficiency and continued learning, two essential domains for living in a community. Their cognitive limits, particularly on the executive functions, could be an obstacle to their involvement in the daily life activities, through their difficulties to plan, anticipate, shift and maintain information in working memory. These high level mental functions can be taught with the CRT program (Cognitive Remediation Therapy - Wykes and Reader 2005) developed in other pathologies and providing an adaptation regarding the developmental level of the person.

METHODS

Firstly, it is essential to determine cognitive developmental levels of the teenager or the adult, using standard tools, such as Wechsler scales. Secondly, functional and/or adaptative levels have to be assessed using specific tools, such as the Vineland Adaptative Behavior Scale 2nd Edition (VABS-II, Sparrow et al., 2005) and the Functional Intervention Scale (EFI, Willaye et al., 2005). Finally, in order to clearly distinguish what are the preserved and impaired cognitive domains, standard tools assessing executive functions such as the Wisconsin Card Sorting Test, the Tower of London, Stroop Test and BADS are used if possible for the patient. The setting of cognitive remediation programs, previously developed for schizophrenic patients, requires adaptation for teenagers and adults with intellectual disabilities, taking into account the limitation of their cognitive abilities. In this paper, we will show that the CRT method for cognitive remediation is particularly relevant for subjects with intellectual disabilities. This method is hence focused on strategies and exercises to improve working memory, categorization and moreover executive functions. Of course this method might need adaptations, with examples based on simplification of the different tasks, notably for verbal materials, and with variations of the media used. These sessions will be part of a wider individualized caring project, allowing the person to transfer the cognitive acquisitions to his/her daily life.

CONCLUSION

The use of cognitive programs adapted to people with intellectual disabilities can provide benefits in the development of autonomy and daily life activities, leading to a better quality of life and self-esteem.

Inhibition deficits in individuals with intellectual disability: a meta-regression analysis

BACKGROUND

Individuals with intellectual disabilities (ID) are characterised by inhibition deficits; however, the magnitude of these deficits is still subject to debate. This meta-analytic study therefore has two aims: first to assess the magnitude of inhibition deficits in ID, and second to investigate inhibition type, age, IQ and the presence/absence of comorbid problems as potential moderators of effect sizes.

METHOD

Twenty-eight effect sizes comparing ID and age matched normal controls on inhibition tasks were included in a random effects meta-regression. Moderators were age, IQ, inhibition type and presence/absence of comorbid disorder.

RESULTS

The analysis showed a medium to large inhibition deficit in ID. Inhibition type significantly moderated effect size, whereas age and comorbid disorder did not. IQ significantly moderated effect size indicating increasing effect size with decreasing IQ, but only in studies that included a sample of ID participants with mean IQ > 70. The analysis indicated comparable deficits in behavioural inhibition and interference control, but no significant deficits in cognitive inhibition and motivational inhibition.

CONCLUSIONS

These results indicate that ID is characterised by a medium to large inhibition deficit in individuals with ID. ID seems not to be characterised by deficits in cognitive and motivational inhibition, which might indicate that distinct processes underlie distinct inhibition capacities.