Intelligence and Executive Functions: A Comprehensive Assessment of Intellectually Gifted Children

OBJECTIVE

Executive functions (EFs) play a key role in cognitive and behavioral functioning. Their multiple forms and implications for daily life behaviors mean they are sometimes equated with intelligence. Several elements even suggest that intellectually gifted children (IGC) may present better executive functioning than typical developing children (TDC, children with intelligence in the average range). However, no study has ever completely tested this hypothesis by a comprehensive assessment of EFs in IGC.

METHOD

Results of 30 IGC and 35 TDC aged from 6 to 16 years old were compared through a comprehensive assessment of EFs (inhibition, flexibility, and planning), comprising performance-based and daily life measures.

RESULTS

IGC did not differ from TDC in EF performance-based measures. However, they scored higher in parents' and some teachers' ratings, suggesting higher indicators of difficulties in daily life.

CONCLUSIONS

Contrary to expectations, high intellectual level does not appear to be associated with superior EFs. Surprisingly, parents and teachers of IGC reported more complaints about their executive functioning in everyday life. We put forward different hypotheses to explain this contrast. Further research is needed to better understand this phenomenon, in which neuropsychology has a fundamental role to play.

Decreased Cognitive Function in Danish Children with Epilepsy

OBJECTIVE

Children with epilepsy have a significantly increased risk of cognitive impairment. EpiTrack Junior is a screening tool developed for fast assessment of cognitive function in children with epilepsy. The tool is validated for German children. This cohort study aims to investigate the differences in cognitive function between healthy Danish children and Danish children diagnosed with epilepsy METHODS:  The cognitive function of 204 healthy controls and 90 children and adolescents diagnosed with epilepsy was examined using EpiTrack Junior. The participants of the control group were aged 6 to 16 years. The patients were aged 6 to 20 years. Statistical analyses were performed with the use of SPSS Statistics.

RESULTS

The control group showed significantly higher scores than the patient group in three of six subtests and total test scores (p-values ranging from 0.033 to <0.001). When grouped according to the EpiTrack Junior guidelines, more patients showed scores "below average" or "poor" compared to the control group. The age-corrected total score was not associated with antiepileptic drug treatment (p-value of 0.732) nor with a history of focal seizures (p-value of 0.215). A history of generalized tonic-clonic seizures (GTCS) was associated with a higher EpiTrack Junior score (p-value of 0.035).

CONCLUSION

The patient group showed statistically significant lower test scores compared to the control group confirming the relationship between impaired cognitive function and childhood epilepsy. Furthermore, a correlation between a higher EpiTrack Junior score and the presence of GTCS was found. Focal seizures and antiepileptic drug treatment were not associated with the EpiTrack Junior score.

Screening of attention and executive functions in pediatric patients at a tertiary epilepsy center

OBJECTIVE

Executive dysfunction is prevalent in children with epilepsy, and associated with poor psychosocial outcome. Sensitive and time effective tools are needed, which capture executive dysfunction across a wide range of impairment. The present study evaluates the applicability of EpiTrack Junior® (EpiTrackJr) as a screening tool at a tertiary epilepsy center, and explore how EpiTrackJr in combination with a subjective measure of everyday attention and executive functions (EFs) may provide clinically important information.

METHODS

Retrospective study including 235 pediatric patients admitted to the Norwegian National Centre for Epilepsy. EpiTrackJr and Behavioral Rating Inventory of Executive Functioning (BRIEF) were used to assess attention and EFs.

RESULTS

27,7% obtained a score categorized as "average/unimpaired", 23% as "mildly impaired", and 47.7% as "significantly impaired" on EpiTrackJr. The distribution of age-corrected EpiTrackJr scores was satisfactory. Performance was related to numbers of anti-seizure medication (ASM load), comorbidity and IQ. We found a significant, but weak correlation between EpiTrackJr performance and the BRIEF Metacognitive Index (r = -0.236, n = 108, p=.014), but no significant correlation with the Behavioral Regulation Index (r = -0.178, n = 108, p=.065).

SIGNIFICANCE

Our results indicate that EpiTrackJr is applicable as a screening tool for attention and EFs in pediatric patients at a tertiary epilepsy center. Impaired test performance was associated with greater ASM load, comorbidity and lower IQ. Performance based measures and behavior ratings likely capture different aspects of EFs. In combination, the two provide important and nonredundant information about the child's EFs in different settings.

Towards the Validation of Executive Functioning Assessments: A Clinical Study

Neuropsychological assessment needs a more profound grounding in psychometric theory. Specifically, psychometrically reliable and valid tools are required, both in patient care and in scientific research. The present study examined convergent and discriminant validity of some of the most popular indicators of executive functioning (EF). A sample of 96 neurological inpatients (aged 18-68 years) completed a battery of standardized cognitive tests (Raven's matrices, vocabulary test, Wisconsin Card Sorting Test, verbal fluency test, figural fluency test). Convergent validity of indicators of intelligence (Raven's matrices, vocabulary test) and of indicators of EF (Wisconsin Card Sorting Test, verbal fluency test, figural fluency) were calculated. Discriminant validity of indicators of EF against indicators of intelligence was also calculated. Convergent validity of indicators of intelligence (Raven's matrices, vocabulary test) was good (r_xtyt = 0.727; R² = 0.53). Convergent validity of fluency indicators of EF against executive cognition as indicated by performance on the Wisconsin Card Sorting Test was poor (0.087 ≤ r_xtyt ≤ 0.304; 0.008 ≤ R² ≤ 0.092). Discriminant validity of indicators of EF against indicators of intelligence was good (0.106 ≤ r_xtyt ≤ 0.548; 0.011 ≤ R² ≤ 0.300). Our conclusions from these data are clear-cut: apparently dissimilar indicators of intelligence converge on general intellectual ability. Apparently dissimilar indicators of EF (mental fluency, executive cognition) do not converge on general executive ability. Executive abilities, although non-unitary, can be reasonably well distinguished from intellectual ability. The present data contribute to the hitherto meager evidence base regarding the validity of popular indicators of EF.

Visual surround suppression in people with epilepsy correlates with attentional-executive functioning, but not with epilepsy or seizure types

PURPOSE

Following reports that an index of visual surround suppression (SI) may serve as a biomarker for an imbalance of cortical excitation and inhibition in different psychiatric and neurological disorders including epilepsy, we evaluated whether SI is associated with seizure susceptibility, seizure spread, and inhibitory effects of antiseizure medication (ASM).

METHODS

In this prospective controlled study, we examined SI with a motion discrimination task in people with genetic generalized epilepsy (GGE) and focal epilepsy with and without focal to bilateral tonic-clonic seizures. Cofactors such as GABAergic ASM, attentional-executive functioning, and depression were taken into account.

RESULTS

Data of 45 patients were included in the final analysis. Suppression index was not related to epilepsy or seizure type, GABAergic ASM treatment or mood. However, SI correlated with attentional-executive functioning (r = 0.32), which in turn was associated with ASM load (r = -0.38). Repeated task administration (N = 7) proved a high stability over a one-week interval (r_tt = 0.89).

CONCLUSIONS

Our results do not support the hypothesis that SI is a reliable biomarker for mechanisms related to inhibition of seizure spread or seizure frequency, i.e., it does not seem to reflect inhibitory capacities in epilepsy. Likewise, SI did not differentiate GGE from focal epilepsy, nor was it influenced by ASM load or mode of action. Thus, in epilepsy, no added value of including SI to routine diagnostics can be concluded.

Associations Between Declining Physical and Cognitive Functions in the Lothian Birth Cohort 1936

BACKGROUND

The ageing process is characterized by declines in physical and cognitive function. However, the relationship between these trajectories remains a topic of investigation.

METHODS

Using four data waves collected triennially between ages 70 and 79, we tested for associations between multiple cognitive ability domains (verbal memory, processing speed, and visuospatial ability) and physical functions (walking speed, grip strength, and lung function). We first tested for associations between linear declines in physical and cognitive functions over the entire 9-year study period, and then, for lead-lag coupling effects between 3-year changes in cognitive and physical functions.

RESULTS

Steeper linear decline in walking speed was moderately correlated with steeper linear declines in each cognitive domain. Steeper linear decline in grip strength was moderately correlated with steeper linear declines in verbal memory and processing speed. Lead-lag coupling models showed that decline in verbal memory was preceded by declines in walking speed and grip strength. By contrast, decline in grip strength was preceded by declines in processing speed and visuospatial ability, and decline in walking speed was preceded by decline in visuospatial ability. Following additional adjustment for covariates, only coupling effects from earlier decline in processing speed to later decline in grip strength remained significant (β = 0.545, p = .006).

CONCLUSION

Our findings provide further evidence of an association between cognitive and physical declines and point to the potential order in which these changes occur. Decline in processing speed in particular may serve as a unique early marker of declining upper body strength.

A Meta-Analysis of Relationships between Measures of Wisconsin Card Sorting and Intelligence

The Wisconsin Card Sorting Test (WCST) represents a widely utilized neuropsychological assessment technique for executive function. This meta-analysis examined the discriminant validity of the WCST for the assessment of mental shifting, considered as an essential subcomponent of executive functioning, against traditional psychometric intelligence tests. A systematic search was conducted, resulting in 72 neuropsychological samples for the meta-analysis of relationships between WCST scores and a variety of intelligence quotient (IQ) domains. The study revealed low to medium-sized correlations with IQ domains across all WCST scores that could be investigated. Verbal/crystallized IQ and performance/fluid IQ were indistinguishably associated with WCST scores. To conclude, the WCST assesses cognitive functions that might be partially separable from common conceptualizations of intelligence. More vigorous initiatives to validate putative indicators of executive function against intelligence are required.

Evaluating the mediating role of executive functions for antiepileptic drugs' effects on IQ in children and adolescents with epilepsy

Several studies suggest that antiepileptic drug (AED) treatment may permanently or reversibly affect intelligence (intelligence quotient [IQ]) in children and adolescents with epilepsy. Since AED treatment preferentially affects attention and executive functions, we evaluated the potentially mediating effect of executive functions in regard to the adverse effects of drug treatment on intelligence. In a retrospective observational study, 178 children and adolescents with refractory and mostly localization-related epilepsies were evaluated in regard to the interrelation of IQ (Wechsler Intelligence Scale for Children [WISC III] short-form), executive functions (EpiTrack-Junior®, a cognitive AED screening test), and drug treatment (drug load). The results indicate that a low IQ was evident in 23%, impaired executive functions in 59% of the patients. Executive functions correlated to IQ (r = 0.60) and the symbol digits and picture arrangement subtests (R² = 0.46) in particular. Odds ratios for impaired executive functions compared to being off drug (33% impaired) increased from 2.0 with one drug (53% impaired) to 9.5 (83% impaired) with at least three drugs. A mediation analysis revealed that drug dependent differences in executive functions mediate the negative effect of the AED load on intelligence. Hence, executive functions appear to link adverse cognitive side effects of AED treatment to intelligence. Considering Catell's two factor model of intelligence, AEDs preferentially affect the aspects of fluid intelligence. The overall impact of AED on intelligence appears mild. It may become relevant, however, when drug-induced impairments persist over longer time intervals during sensitive developmental phases. This issue needs to be addressed in future longitudinal studies.