Intelligence measures as diagnostic tools for children with specific learning disabilities

The Intellectual Profile of Adults with Specific Learning Disabilities

Despite growing research on adults with specific learning disabilities (SLDs), evidence concerning their intellectual profile remains scarce. The present study examined the results of the administration of the Wechsler Adult Intelligence Scale-Fourth Edition to 301 adults diagnosed with SLDs and compared them to the results obtained from previous studies with a large sample of children with SLDs. The results showed that: (1) as observed among children, adults with SLDs also presented higher scores in the subtests implying reasoning (associated with the General Ability Index, GAI) and lower scores in the subtests involving working memory and processing speed; (2) the discrepancy between full-scale IQ and the GAI had a good predictive value in discriminating adults with and without SLDs; (3) the four-factor hierarchical structure of intelligence proposed for the general adult population held for adults with SLDs as well, even though there were substantial differences in the loadings and a five-factor structure could be more appropriate; (4) similarities as well as strong differences were present between adults and children with SLDs. In adults, scores on subtests were generally lower, particularly in working memory and processing speed. However, in some cases, scores were equal or even higher (as in the "Similarity" subtest) among adults, meaning that the discrepancy between the full scale and the GAI was accentuated.

Cognitive Profile Discrepancies among Typical University Students and Those with Dyslexia and Mixed-Type Learning Disorder

BACKGROUND

Previous studies have identified areas of cognitive weakness in children diagnosed with Specific Learning Disorder (SLD), in the areas of working memory and processing speed in particular. In adulthood, this literature is still scant, and no studies have compared the cognitive profile of university students with dyslexia (DD) with that of students with Mixed-type SLD.

METHOD

Thus, in this study, the WAIS-IV was used to examine the cognitive functioning of three groups of university students: students with DD, with Mixed-type SLD, and typical students. Statistical analyses were performed to examine differences in WAIS-IV FSIQ, main, and additional indexes and subtests.

RESULTS

The results showed strengths in perceptual reasoning and good verbal comprehension abilities in both the DD and Mixed-type SLD group, with weaknesses in working memory and processing speed, leading to a pattern of a better General Ability Index (GAI) than Cognitive Proficiency Index (CPI) in both clinical groups. Thus, discrepancies between GAI and CPI, well documented in children with SLD, still manifest in adulthood in university students. Our findings also revealed worse cognitive performance in university students with mixed learning disorder relative to students with only a reading deficit.

CONCLUSIONS

The cognitive features and distinctive subtest profiles that emerged should guide the assessment and the definitions of intervention programs, special educational needs, and strategies of compensation.

Low discriminative power of WISC cognitive profile in developmental dyscalculia

BACKGROUND

The role of domain-general cognitive abilities in the etiology of Developmental Dyscalculia (DD) is a hotly debated issue.

AIMS

In the present study, we tested whether WISC-IV cognitive profiles can be useful to single out DD.

METHODS AND PROCEDURES

Using a stringent 2-SD cutoff in a standardized numeracy battery, we identified children with DD (N = 43) within a clinical sample referred for assessment of learning disability and compared them in terms of WISC cognitive indexes to the remaining children without DD (N = 100) employing cross-validated logistic regression.

OUTCOMES AND RESULTS

Both groups showed higher Verbal Comprehension and Perceptual Reasoning than Working Memory and Processing Speed, and DD scores were generally lower. Predictive accuracy of WISC indexes in identifying DD individuals was low (AUC = 0.67) and it dropped to chance level in discriminating DD from selected controls (N = 43) with average math performance but matched on global IQ. The inclusion of a visuospatial memory score as an additional predictor did not improve classification accuracy.

CONCLUSIONS AND IMPLICATIONS

These results demonstrate that cognitive profiles do not reliably discriminate DD from non-DD children, thereby weakening the appeal of domain-general accounts.

The structure, profile, and diagnostic significance of intelligence in children with ADHD are impressively similar to those of children with a specific learning disorder

This study examines the structure, profile, and diagnostic significance of intelligence in a group of 948 children diagnosed with attention deficit/hyperactivity disorder (ADHD) assessed with the WISC-IV and compared with children with specific learning disorders (SLDs) and with typically developing children. Based on four indexes, the WISC-IV configuration found in TD resulted applicable to ADHD, but with generally lower loadings on g. The Perceptual Reasoning and Verbal Comprehension indexes not only had higher loadings compared to the other two indexes but also represented the relative strengths of children with ADHD, as previously observed for children with SLD. In fact, the WISC pattern could be successfully used for discriminating between ADHD and TD, but not between ADHD and SLD. The latter result was not due to a co-occurrence of a learning disorder because the presence or absence of an associated diagnosis of SLD negligibly affected the pattern observed in ADHD. We concluded that the characteristics of intelligence in children with ADHD can be relevant for assessing this disorder, and that ADHD and SLDs share largely similar underlying cognitive features.

Intellectual profile in school-aged children with borderline intellectual functioning

BACKGROUND

Little is currently known about borderline intellectual functioning (BIF), a condition characterized by an intelligence quotient between one and two standard deviations below the average, that affects about 14% of the population.

AIMS

The present study aimed to analyze the intellectual profile of school-aged children with BIF.

METHOD AND PROCEDURE

The WISC-IV was administered to 204 children with BIF attending Italian primary and lower secondary school, and their profile was compared with that of a control group of typically developing (TD) children.

RESULTS

The WISC-IV profile of the children with BIF differed from that of the TD children, and the former's performance was worse than the latter's in all the measures considered. The children with BIF also showed significant differences between the four main factor indices, scoring lowest for working memory, while the TD control group's profile was flat (as expected on the grounds of standardization criteria). No differences were found between the profiles of children with versus without a comorbid neurodevelopmental disorder.

DISCUSSION

Our results support the hypothesis that individuals with BIF have a characteristic profile with specific weaknesses.

Are children with developmental dyslexia all the same? A cluster analysis with more than 300 cases

Reading is vital to every aspect of modern life, exacerbated by reliance of the internet, email, and social media on the written medium. Developmental dyslexia (DD) characterizes a disorder in which the core deficit involves reading. Traditionally, DD is thought to be associated with a phonological impairment. However, recent evidence has begun to suggest that the reading impairment in some individuals is provoked by a visual processing deficit. In this paper, we present WISC-IV data from more than 300 Italian children with a diagnosis of DD to investigate the manifestation of phonological and visual subtypes. Our results indicate the existence of two clusters of children with DD. In one cluster, the deficit was more pronounced in the phonological component, while both clusters were impaired in visual processing. These data indicate that DD may be an umbrella term that encompasses different profiles. From a theoretical perspective, our results demonstrate that dyslexia cannot be explained in terms of an isolated phonological deficit alone; visual impairment plays a crucial role. Moreover, general rather than specific accounts of DD are discussed.

The intellectual profile of children with autism spectrum disorders may be underestimated: A comparison between two different batteries in an Italian sample

Intelligence measures are typically used in the assessment of children with autism spectrum disorders (ASD), but there is a paucity of research on the implications of such testing. In the present study, we examined children with ASD using two of the most largely adopted instruments, i.e., the WISC-IV, arguably the most utilized scale in the world; and the Leiter-3, a nonverbal scale that also excludes, from the IQ calculation, working memory and processing speed, which are points of weakness in ASD. Results showed that IQ and indices of these two batteries are strongly correlated. However, the WISC-IV IQ might underestimates the potential of children with ASD, particularly in children with a low functioning profile. These hold true for both the full scale IQ and three out of four indices of the WISC-IV, with remarkable implications for both assessment and treatment of these children. Practitioners working with children with ASD should be aware that the battery that they are using might severely affect the estimation of these children's potential.

Using Z and age-equivalent scores to address WISC-IV floor effects for children with intellectual disability

BACKGROUND

The Wechsler Intelligence Scale for Children - Fourth Edition often produces floor effects in individuals with intellectual disability. Calculating respondents' Z or age-equivalent scores has been claimed to remedy this problem.

METHOD

The present study applied these methods to the Wechsler Intelligence Scale for Children - Fourth Edition scores of 198 individuals diagnosed with intellectual disability. Confirmatory factor analysis and profile analysis were conducted using a Bayesian approach.

RESULTS

The intelligence structure in intellectual disability resembled the one previously reported for typical development, suggesting configural but not metric invariance. When Z or age-equivalent scores (but not traditional scaled scores) were used, the average profile resembled the one previously reported for other neurodevelopmental disorders.

CONCLUSIONS

Both methods avoided any floor effects, generating similar but not identical profiles. Despite some practical and conceptual limitations, age-equivalent scores may be easier to interpret. This was true even for a subgroup of individuals with more severe disabilities (mean IQ < 43).

The discrepancy between verbal and visuoperceptual IQ in children with a specific learning disorder: An analysis of 1624 cases

Children with a specific learning disorder (SLD) are often characterized by marked intellectual strengths and weaknesses. In the last few years, research has focused on a common discrepancy between low working memory and processing speed on the one hand, and high verbal and visuoperceptual intelligence on the other. SLD profiles featuring a specific discrepancy between verbal and visuoperceptual abilities have been only marginally considered, however, and their systematic comparison vis-à-vis typically-developing (TD) populations has yet to be conducted. The present study examined a dataset of 1624 WISC-IV profiles of children with a diagnosis of SLD. It emerged that the proportion of children with a Verbal Comprehension Index (VCI) at least 1.5 SD (22 standardized points) lower than their scores on the Perceptual Reasoning Index (PRI) was larger than the proportion of SLD children with the opposite discrepant profile; it was also larger than the same proportion found among TD children. Comparing the two discrepant profiles revealed that the children also differed by type of learning difficulty, gender, and performance in the WISC-IV Symbol search task. Further examination suggested that children who were discrepant and also distinctly poor in visuoperceptual intelligence were particularly slow in general processing.

WISC-III Cognitive Profiles in Children with ADHD: Specific Cognitive Impairments and Diagnostic Utility

This study aimed to investigate the presence of specific cognitive impairments and the diagnostic utility of the WISC-III in children with ADHD. Ninety-eight children with ADHD and 81 children without ADHD matched by age and gender (control group), between the ages of 6 and 12 years, participated in the study. Children with ADHD revealed the most pronounced deficits in the subtests tapping working memory and processing speed. Freedom from Distractibility was the cognitive profile most impaired and that showed the highest diagnostic accuracy to discriminate children with ADHD. The optimal cutoff scores of the most common WISC-III cognitive profiles revealed greater diagnostic accuracy than the traditional approach of full or partial profiles. Taken together, these results suggested that in the context of a comprehensive psychological assessment, the WISC may provide knowledge about the specific cognitive strengths and weaknesses that characterize this disorder and may be useful in the decision-making process relative to ADHD diagnosis.

A Cross-Modal Working Memory Binding Span Deficit in Reading Disability

Successful reading demands the ability to combine visual-phonological information into a single representation and is associated with an efficient short-term memory. Reading disability may consequently involve an impaired working memory binding of visual and phonological information. The present study proposes two span tasks for assessing visual-phonological working memory binding. The tasks involved memorizing cross-modal associations between nonsense figures and nonwords, and they were administered, with other working memory measures, to children with and without a reading disability. The tasks required recognizing which figure was associated with a given nonword and recalling which nonword was associated with a given figure. Children with a reading disability had a similar significant deficit in both cross-modal binding tasks when compared with the control children, and the difference remained significant even after controlling for other verbal and nonverbal working memory measures. The cross-modal binding tasks described here seem to capture a core aspect of working memory associated with reading and may be a useful procedure for assessing reading disabilities.

Short Forms of Wechsler Scales Assessing the Intellectually Gifted Children Using Simulation Data

Intellectual giftedness is usually defined in terms of having a very high Intellectual Quotient (IQ). The intellectual capacity is assessed by a standardized test such as the Wechsler Intelligence Scale for Children (WISC). However, the identification of intellectually gifted children (IGC) often remains time-consuming. A short-form WISC can be used as a screening instrument. The practitioners and researchers in this field can then make a more in-depth evaluation of the IGC's cognitive and socioemotional characteristics if needed. The aim of our study is thus to determine the best short tests, in terms of their psychometric qualities, for the identification of IGC. The current study is composed of three-step analyses. Firstly, we created nine IQs short forms (IQ_SF) with 2-subtests, and nine IQ_SF with 4-subtests from the WISC-IV (Wechsler, 2005). Secondly, we estimated psychometric parameters (i.e., reliability and validity) from empirical and simulated dataset with WISC-IV. The difference in the estimation of psychometric qualities of each IQ_SF from the simulated data is very close to those derived from empirical data. We thus selected the three best IQ_SF based on these psychometrics parameters estimated from simulated datasets. For each selected short form of the WISC-IV, we estimated the screening quality in our sample of IGC. Thirdly, we created IQ_SF with 2- and 4-subtests from the WISC-V (Wechsler, 2016) with simulated dataset. We then highlighted the three best short forms of WISC-V based on the estimated psychometric parameters. The results are interpreted in terms of validity, reliability and screening quality of IGC. In spite of the important changes in the WISC-V, our findings show that the 2-subtest form, Similitaries + Matrix Reasoning, and 4-subtest form, Similitaries + Vocabulary + Matrix Reasoning + Block Design, are the most efficient to identify the IGC at the two recent versions of Wechsler scales. Finally, we discuss the advantages and drawbacks of a brief assessment of intellectual aptitudes for the identification of the IGC.

Analyzing Global Components in Developmental Dyscalculia and Dyslexia

The study examined whether developmental deficits in reading and numerical skills could be expressed in terms of global factors by reference to the rate and amount (RAM) and difference engine (DEM) models. From a sample of 325 fifth grade children, we identified 5 children with dyslexia, 16 with dyscalculia, 7 with a “mixed pattern,” and 49 control children. Children were asked to read aloud words presented individually that varied for frequency and length and to respond (either vocally or manually) to a series of simple number tasks (addition, subtraction, number reading, and number comparisons). Reaction times were measured. Results indicated that the deficit of children with dyscalculia and children with a mixed pattern on numerical tasks could be explained by a single global factor, similarly to the reading deficit shown by children with dyslexia. As predicted by the DEM, increases in task difficulty were accompanied by a corresponding increase in inter-individual variability for both the reading and numerical tasks. These relationships were constant across the four groups of children but differed in terms of slope and intercept on the x-axis, indicating that two different general rules underlie performance in reading and numerical skills. The study shows for the first time that, as previously shown for reading, also numerical performance can be explained with reference to a global factor. The advantage of this approach is that it takes into account the over-additivity effect, i.e., the presence of larger group differences in the case of more difficult conditions over and above the characteristics of the experimental conditions. It is concluded that reference to models such as the RAM and DEM can be useful in delineating the characteristics of the dyscalculic deficit as well as in the description of co-morbid disturbances, as in the case of dyslexia and dyscalculia.