Quantifying practice effects in longitudinal research with the WISC-R and WAIS-R: a study of children and adolescents with hemophilia and male siblings without hemophilia

Prior test experience confounds longitudinal tracking of adolescent cognitive and motor development

Background

Accurate measurement of trajectories in longitudinal studies, considered the gold standard method for tracking functional growth during adolescence, decline in aging, and change after head injury, is subject to confounding by testing experience.

Methods

We measured change in cognitive and motor abilities over four test sessions (baseline and three annual assessments) in 154 male and 165 female participants (baseline age 12–21 years) from the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA) study. At each of the four test sessions, these participants were given a test battery using computerized administration and traditional pencil and paper tests that yielded accuracy and speed measures for multiple component cognitive (Abstraction, Attention, Emotion, Episodic memory, Working memory, and General Ability) and motor (Ataxia and Speed) functions. The analysis aim was to dissociate neurodevelopment from testing experience by using an adaptation of the twice-minus-once tested method, which calculated the difference between longitudinal change (comprising developmental plus practice effects) and practice-free initial cross-sectional performance for each consecutive pairs of test sessions. Accordingly, the first set of analyses quantified the effects of learning (i.e., prior test experience) on accuracy and after speed domain scores. Then developmental effects were  determined for each domain for accuracy and speed having removed the measured learning effects.

Results

The greatest gains in performance occurred between the first and second sessions, especially in younger participants, regardless of sex, but practice gains continued to accrue thereafter for several functions. For all 8 accuracy composite scores, the developmental effect after accounting for learning was significant across age and was adequately described by linear fits. The learning-adjusted developmental effects for speed were adequately described by linear fits for Abstraction, Emotion, Episodic Memory, General Ability, and Motor scores, although a nonlinear fit was better for Attention, Working Memory, and Average Speed scores.

Conclusion

Thus, what appeared as accelerated cognitive and motor development was, in most cases, attributable to learning. Recognition of the substantial influence of prior testing experience is critical for accurate characterization of normal development and for developing norms for clinical neuropsychological investigations of conditions affecting the brain.

Community-based Skill Building Intervention to Enhance Health Literacy Among Older Rural Adults

The purpose of this article is to report the outcomes of a skill building intervention to improve general health literacy and health literacy about complementary and alternative therapies (CAM) among older rural adults. The intervention was implemented in eight rural communities. Descriptive statistics and general linear modeling were used for analysis. A total of 127 older adults completed the initial session and Time 1 questionnaire, 67 (51%) completed the intervention sessions and Time 2 questionnaire, and 52 (40.9%) completed the Time 3 questionnaire five months later. CAM health literacy scores and scores on one general health literacy measure were significantly higher at Time 2 compared to Time 1 and 3. The decline in scores over time suggests a need for continuing strategies to support older adults' health literacy. Assisting older adults to make safe health care choices is a critical role for investigators, nurses, and other health care providers.

Cognitive and Motor Outcome in Patients with Early-Detected Central Congenital Hypothyroidism Compared with Siblings

CONTEXT

Early treatment of primary congenital hypothyroidism (CH) prevents irreversible brain damage. Contrary to primary CH, outcome studies on central CH are scarce. Most patients with central CH have multiple pituitary hormone deficiencies (MPHD); these patients are also at risk for neonatal hypoglycemia.

OBJECTIVE

To assess cognitive and motor outcome in patients with early-treated central CH detected by the Dutch neonatal screening.

METHODS

In this cross-sectional study, primary outcome full-scale intelligence quotient (FSIQ) was measured in patients with MPHD and patients with isolated central CH born between January 1, 1995, and January 1, 2015, with siblings as controls. Secondary outcomes were intelligence test subscales and motor function. Linear mixed models were used to compare both patient groups and siblings, followed by post hoc tests in case of significant differences.

RESULTS

Eighty-seven patients (52 MPHD; 35 isolated central CH) and 52 siblings were included. Estimated marginal means for FSIQ were 90.7 (95% CI 86.4-95.0) in patients with MPHD and 98.2 (95% CI 93.0-103.5) in patients with isolated central CH. While patients with MPHD scored lower FSIQs than siblings (mean difference -7.9 points, 95% CI -13.4 to -2.5; P = .002), patients with isolated central CH did not. Processing speed was lower in both patient groups than in siblings (mean differences -10.5 and -10.3 points). Motor difficulties occurred significantly more often in patients (33%) versus siblings (5%; P = .004).

CONCLUSION

In early-treated central CH, FSIQ is comparable with siblings in patients with isolated central CH, while patients with MPHD have a significantly lower FSIQ. This may be explained by disease-specific consequences of MPHD, such as neonatal hypoglycemia and more severe hypothyroidism.

Effects of prior testing lasting a full year in NCANDA adolescents: Contributions from age, sex, socioeconomic status, ethnicity, site, family history of alcohol or drug abuse, and baseline performance

Longitudinal study provides a robust method for tracking developmental trajectories. Yet inherent problems of retesting pose challenges in distinguishing biological developmental change from prior testing experience. We examined factors potentially influencing change scores on 16 neuropsychological test composites over 1 year in 568 adolescents in the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA) project. The twice-minus-once-tested method revealed that performance gain was mainly attributable to testing experience (practice) with little contribution from predicted developmental effects. Group mean practice slopes for 13 composites indicated that 60% to ∼100% variance was attributable to test experience; General Ability accuracy showed the least practice effect (29%). Lower baseline performance, especially in younger participants, was a strong predictor of greater gain. Contributions from age, sex, ethnicity, examination site, socioeconomic status, or family history of alcohol/substance abuse were nil to small, even where statistically significant. Recognizing that a substantial proportion of change in longitudinal testing, even over 1-year, is attributable to testing experience indicates caution against assuming that performance gain observed during periods of maturation necessarily reflects development. Estimates of testing experience, a form of learning, may be a relevant metric for detecting interim influences, such as alcohol use or traumatic episodes, on behavior.

Poorer cognitive performance in perinatally HIV-infected children versus healthy socioeconomically matched controls

BACKGROUND

Despite the declining incidence of severe neurological complications such as HIV encephalopathy, human immunodeficiency virus (HIV) infection in children is still associated with a range of cognitive problems. Although most HIV-infected children in industrialized countries are immigrants with a relatively low socioeconomic status (SES), cognitive studies comparing HIV-infected children to SES-matched controls are lacking.

METHODS

This cross-sectional study included perinatally HIV-infected children and controls matched for age, sex, ethnicity, and SES, who completed a neuropsychological assessment evaluating intelligence, information processing speed, attention, memory, executive function, and visual-motor function. Multivariate normative comparison was used to assess the prevalence of cognitive impairment in the HIV-infected group. Multivariable regression analyses were performed to identify HIV- and combination antiretroviral therapy-related factors associated with cognitive performance.

RESULTS

In total, 35 perinatally HIV-infected children (median age, 13.8 years; median CD4 count, 770 × 10(6) cells/L; 83% with undetectable HIV RNA) and 37 healthy children (median age, 12.1 years) were included. HIV-infected children scored lower than the healthy controls on all cognitive domains (eg, intelligence quotient [IQ], 76 [standard deviation {SD}, 15.7] vs 87.5 [SD, 13.6] for HIV-infected vs healthy children; P = .002). Cognitive impairment was found in 6 HIV-infected children (17%). The Centers for Disease Control and Prevention (CDC) clinical category at HIV diagnosis was inversely associated with verbal IQ (CDC clinical category C: coefficient -22.98; P = .010).

CONCLUSIONS

Our results show that cognitive performance of HIV-infected children is poor compared with that of SES-matched healthy controls. Gaining insight into these cognitive deficits is essential, as subtle impairments may progress to more pronounced complications that will influence future intellectual performance, job opportunities, and community participation of HIV-infected children.

Four-year longitudinal performance of a population-based sample of healthy children on a neuropsychological battery: the NIH MRI study of normal brain development

The National Institutes of Health (NIH) Magnetic Resonance Imaging (MRI) Study of Normal Brain Development is a landmark study in which structural and metabolic brain development and behavior are followed longitudinally from birth to young adulthood in a population-based sample of healthy children. Cross-sectional findings from the neuropsychological test battery have been previously described (Waber et al., 2007). The present report details 4-year longitudinal neuropsychological outcomes for those children who were aged 6 to 18 years at baseline (N = 383), of whom 219 (57.2%) completed all 3 visits. Primary observations were (1) individual children displayed considerable variation in scores across visits on the same measures; (2) income-related differences were more prominent in the longitudinal than in the cross-sectional data; (3) no association between cognitive and behavioral measures and body mass index; and (4) several measures showed practice effects, despite the 2-year interval between visits. These data offer an unparalleled opportunity to observe normative performance and change over time on a set of standard and commonly used neuropsychological measures in a population-based sample of healthy children. They thus provide important background for the use and interpretation of these instruments in both research settings and clinical practice.

The Flynn Effect in the WISC Subtests Among School Children Tested for Special Education Services

The Flynn effect, a secular rise in IQ seen throughout the world, was examined on the WISC-R and WISC-III subtests in a longitudinal sample of more than 2,500 school children who were tested between 1974 and 2002. Multivariate analysis of variance and multiple regression analyses revealed that all the subtests experienced significant decreases in scores on the introduction of the WISC-III, as expected because of the Flynn effect, with the exception of Information and Digit Span. (Mazes was not included in the analyses because of a limited sample size.) On Picture Arrangement and Coding, however, children who were repeatedly tested on the WISC-III also experienced significant decreases compared with children who were repeatedly tested on the WISC-R. These findings add to the growing literature comparing the magnitude of the Flynn effect on crystallized versus fluid measures. Implications for special education testing and the current WISC-IV are discussed.

The Maudsley early onset schizophrenia study: cognitive function over a 4-year follow-up period

Generalized cognitive deficits have been consistently reported in adolescents with early onset schizophrenia (EOS; defined as onset before the age of 17 years). The impact on cognition of potential interactions between disease pathology and brain maturation remains unclear. We therefore compared cognitive function between 20 EOS patients and 20 healthy controls matched on age, gender, and parental socioeconomic status at 2 time points, when aged 15.58 (2.27) and after a mean interval of 4 +/- 1.08 years when aged 19.46 (2.21) years. Repeated measures analyses revealed no differences between patients and controls in the degree of change over this time period in general intellectual function and planning ability as measured by the Tower of London. There was deterioration in the verbal memory and attentional control index scores from the Wechsler Memory Scale-Revised but relative improvement in Part A of the Trail Making Test. Patients' level of symptomatology as well as the type and dose of medication were comparable at both time points. We conclude that most aspects of cognitive function remain relatively stable in EOS patients during adolescence; there is evidence for deterioration in immediate verbal memory and attention while speed of information processing may show improvement.

Effects of perinatal HIV infection and associated risk factors on cognitive development among young children

OBJECTIVE

We examined the effect of HIV, in combination with other important health and social factors, on the development of cognitive abilities of children perinatally exposed to HIV.

METHODS

Serial cognitive assessments were performed for 117 children who were infected vertically and 422 children who were exposed to but not infected with HIV, in a multicenter, natural history, longitudinal study. Repeated-measures analyses were used to evaluate the neurocognitive development of children between the ages of 3 and 7 years, as measured by the McCarthy Scales of Children's Abilities (MSCA).

RESULTS

Children with HIV infection and class C status scored significantly lower in all domains of cognitive development, across all time points, than did those who were HIV infected without an AIDS-defining illness and those who were HIV exposed but not infected. There were no significant differences between the 2 latter groups in General Cognitive Index or specific domain scores. Rates of change in cognitive development were comparable (parallel) among all 3 groups over a period of 4 years. Factors that were associated consistently and significantly with lower mean scores were HIV status, number of times an examination had been completed previously, primary language, maternal education, and gender. No factors were related to rate of change of any mean domain score.

CONCLUSIONS

An early AIDS-defining illness increased the risk of chronic static encephalopathy during the preschool and early school age years. Children with HIV infection but no class C event performed as well as noninfected children in measures of general cognitive ability. No significantly different profiles of strengths and weaknesses for verbal, perceptual-performance, quantitative, or memory functioning were observed among children with or without HIV infection. A number of factors were found to have significant effects on the mean scores of children in all 3 groups; however, they were not related to the rate at which learning occurred.

Cognitive decline with immunologic and virologic stability in four children with human immunodeficiency virus disease

This case series describes 4 children with vertically acquired human immunodeficiency virus (HIV) infection who exhibited immunologic, virologic, and clinical stability while on a protease inhibitor-containing highly active antiretroviral therapy (HAART) regimen, yet demonstrated significant cognitive decline as measured by standardized intelligence tests. A retrospective review of 107 patient records of children with HIV infection on HAART treatment protocols was conducted. Four patients were identified who responded to protease inhibitor-containing HAART therapy with sustained viral load suppression, and stable immunologic and medical parameters, yet demonstrated significant cognitive decline. Such discordance between biological and clinical markers previously has been reported in adults with HIV disease but not in children. This observed decline in neurocognitive functioning despite stable medical parameters suggests that HAART regimens that are effective for systemic disease may not be as effective for the central nervous system (CNS), perhaps because the antiretrovirals do not penetrate adequately into the CNS. Of note, 3 of these 4 patients did not have zidovudine (ZDV) included in their HAART regimen. The only patient who was treated with ZDV containing regimen received 90 mg/m(2) every 6 hours, which is at the lower end of the recommended ZDV pediatric full-dose range (90 mg/m(2) to 120 mg/m(2)). Two of the 4 patients began ZDV at 120 mg/m(2) every 6 hours following the decline in their cognitive test scores and subsequently showed improved or stable functioning as evidenced by the results of follow-up psychometric testing. Long-term prospective studies using both systemic and CNS measures are necessary to further investigate the effects of HAART in children with HIV disease. Longitudinal cognitive assessments of children receiving HAART appear indicated to identify cognitive decline and to provide appropriate therapeutic intervention when manifestations of HIV-related CNS disease progression occur.