Instability in longitudinal childhood IQ scores of Guatemalan high SES individuals born between 1941-1953

A longitudinal investigation of cognitive functioning and its relationship to symptom severity and academic functioning in treatment seeking youth with AHDH

Background:

Children with ADHD tend to present with poorer cognitive functioning leaving them more vulnerable to a range of negative outcomes. To date, only a handful of longitudinal studies have examined the stability of Wechsler composite scores in children and adolescents with ADHD, and none of them used a more recent version of the Wechsler Intelligence Scales for Children (WISC), than the WISC-III.

Objective:

The present study investigates the cognitive stability and its longitudinal relationship with the severity of the child’s ADHD symptoms and school grades.

Method:

Cognitive functioning was measured with the fourth editions of the WISC-IV or the Wechsler Adult Intelligence Scales (WAIS-IV) at baseline and at a 3-4-year follow-up in children with ADHD (n = 125, mean age = 11.40 years, SD = 3.27) and a Control group of schoolchildren (n = 59, mean age = 11.97 years, SD = 2.15). The stability of cognitive functioning and the relationship between cognitive functioning, ADHD and grades were evaluated using linear mixed models and logistic regression.

Results:

Standardized composite scores of Full scale IQ, Verbal Comprehension, and Processing Speed declined between baseline and follow-up in the ADHD group. ADHD symptom scores were associated with Working Memory scores. Together, the severity of concurrent ADHD symptoms and lower scores for verbal comprehension at baseline and follow-up were associated with an increased risk of not achieving grades at follow-up in youth with ADHD.

Conclusions:

Youth with ADHD often present with cognitive impairments, not improved over time. Together these increase the risk of poorer academic outcomes. Concurrent evaluation of symptom severity and cognitive functions can add potentially useful information in terms of treatment planning, and school supports to prevent school failure.

Comparison of a set of cognitive ability screening test for primary school-aged children in Indonesia

BACKGROUND Monitoring children’s intellectual development is important to align their educational needs. This study compared nonverbal intelligence subtest of the cognitive test battery for Individuals with or without intellectual disability (CIID) to measure visual logical reasoning, verbal intelligence subtest (verbal fluency [VF]–animal test) to assess vocabulary and semantic memory, and the modified Indonesian version of Hopkins verbal learning test (IHVLT) to assess learning ability and episodic memory, against the Wechsler intelligence scale for children (WISC) as an alternative cognitive screening tool in school-aged children. METHODS A cross-sectional study was conducted in 145 grade 1–6 elementary school students in Jakarta between March and May 2017. Performance on the CIID subtest, VF, and modified IHVLT was assessed by a pediatrician, and the WISC test was performed by a psychologist. The associations between variables were evaluated using nonparametric Spearman’s rank correlations, regressions, and box plots. RESULTS The correlation between total intelligence quotient (IQ) WISC and CIID was 0.42 (p<0.001) and 0.34 (p<0.001) for both IHVLT and VF. Box plots suggested possible discriminative capacity of CIID but insufficient specificity. However, CIID was associated with stunting (height) and health (weight) independent of age, sex, father’s education, or income. CONCLUSIONS The CIID subtest series, VF, and modified IHVLT correlated with total IQ WISC. However, CIID may be better to test predictors of poor cognitive performance in primary school-aged children than an IQ screening test.

Differences and secular trends in childhood IQ trajectories in Guatemala City

This study documents differences in childhood IQ trajectories of Guatemala City children, aged 6-15 years and born 1961-1993, according to school attended, height-for-age Z-scores (HAZ) and over time (Flynn effect). IQ data come from the Universidad del Valle de Guatemala Longitudinal Study of Child and Adolescent Development. IQ was measured using standardised tests from the Otis-Lennon Mental Ability Test-series. A multilevel model was developed to describe 60,986 IQ observations (level 1), in 22,724 children (level 2), in five schools representing students of different socioeconomic status (SES) (level 3). Average IQ trajectories differed by school. The difference in average IQ at age 11 years between the students of high and low SES schools was 28.7 points. A one-unit increase in HAZ was associated with a 1.42 (0.72, 2.11) unit higher IQ if HAZ was <0, this association was stronger in public compared to private schools. Conversely, one unit increase in HAZ was only associated with a 0.3 (0.001, 0.5) unit higher IQ if HAZ was ≥0. With each birth year increase, IQ at age 11 years increased by 0.14 (95% CI 0.12, 0.16) units, although this Flynn effect attenuated slightly across adolescence. We found no evidence of secular change in the inequality in IQ trajectories (according to school or HAZ). Shorter children from disadvantaged schools in Guatemala City have lower IQ than their taller and wealthier peers, possibly reflecting the damaging effects of poor early life environments both for linear growth and cognitive development.