Raising IQ among school-aged children: Five meta-analyses and a review of randomized controlled trials

Multivariate prediction of cognitive performance from the sleep electroencephalogram

Human cognitive performance is a key function whose biological foundations have been partially revealed by genetic and brain imaging studies. The sleep electroencephalogram (EEG) is tightly linked to structural and functional features of the central nervous system and serves as another promising biomarker. We used data from MrOS, a large cohort of older men and cross-validated regularized regression to link sleep EEG features to cognitive performance in cross-sectional analyses. In independent validation samples 2.5-10% of variance in cognitive performance can be accounted for by sleep EEG features, depending on the covariates used. Demographic characteristics account for more covariance between sleep EEG and cognition than health variables, and consequently reduce this association by a greater degree, but even with the strictest covariate sets a statistically significant association is present. Sigma power in NREM and beta power in REM sleep were associated with better cognitive performance, while theta power in REM sleep was associated with worse performance, with no substantial effect of coherence and other sleep EEG metrics. Our findings show that cognitive performance is associated with the sleep EEG (r = 0.283), with the strongest effect ascribed to spindle-frequency activity. This association becomes weaker after adjusting for demographic (r = 0.186) and health variables (r = 0.155), but its resilience to covariate inclusion suggest that it also partially reflects trait-like differences in cognitive ability.

Association between Elevated Iodine Intake and IQ among School Children in Portugal

The goal of this work was to examine whether elevated iodine intake was associated with adverse effects on IQ among school-age children in Portugal. In a representative sample of children from the north of the country, IQ percentiles by age (assessed with Raven’s Colored Progressive Matrices) were dichotomized to <50 (“below-average” IQs) and ≥50. Morning urine iodine concentrations, corrected for creatinine, were dichotomized to <250 µg/g and ≥250 µg/g, according to the European Commission/Scientific Committee on Food’s tolerable upper level of daily iodine intake for young children. Data were examined with Chi-square tests, logistic regression, and GLM univariate analysis. The sample (N = 1965) was classified as generally iodine-adequate (median urinary iodine concentration = 129 µg/L; median iodine-to-creatinine ratio = 126 µg/g) according to the WHO’s criteria. A greater proportion of children in the ≥250 µg/g group had below-average IQs, compared to children with less than 250 µg/g (p = 0.037), despite a sizable (though non-significant) proportion of children in the less-than-250 µg/g group also presenting below-average IQs, at the bottom of the iodine distribution (<50 µg/g). The proportion of below-average IQs increased with increasingly elevated iodine concentrations (p = 0.047). The association remained significant after the adjustment for confounders, with the elevated iodine group showing increased odds of having below-average IQs when compared with the non-elevated iodine group (OR 1.55; 95% CI 1.11−2.17; p = 0.011). Consistently, the former group presented a lower mean IQ than the latter (p = 0.006). High iodine intake was associated with lower IQs even in a population classified as iodine-adequate. These results bear on child cognition and on initiatives involving iodine supplementation.

Intelligenzsteigerung durch Neuroenhancement?

Zusammenfassung. Die menschliche Intelligenz gehört zu den bestuntersuchten psychologischen Merkmalen, in denen interindividuelle Differenzen bestehen. Die mehr als 100jährige Forschungsgeschichte hat einen hoch belastbaren Wissensstand hervorgebracht; dieser umfasst die Definition, die Psychometrie, die (ontogenetische) Entwicklung, die Struktur, die Vorhersagekraft für real-life-Variablen, das Wissen über elementar-kognitive, verhaltensgenetische und neurobiologische Grundlagen der Intelligenz, u.v.m. Jüngst steht zudem die Frage des ‚enhancements‘ der Intelligenz im Fokus, eine Frage, die nicht zuletzt durch die aktuelle philosophische Strömung des Transhumanismus stark an Bedeutung gewinnt. Der Transhumanismus nimmt eine substanzielle Erhöhung (enhancement) von Fähigkeiten und anderen (auch) psychologischen Eigenschaften des Menschen ins Zentrum und postuliert, dass ein soziokultureller Fortschritt – und letztlich das Überlegen des Homo Sapiens und unseres Planeten – erst durch technologischen Fortschritt ermöglicht werde. Viele Transhumanisten stellen eine substanzielle Steigerung der Intelligenz in den Vordergrund, die primär durch (neuro–)‌technologische und pharmakologische Maßnahmen zu bewerkstelligen seien. Diese Debatten sind jedoch oft gekennzeichnet durch übertrieben optimistische Annahmen der Möglichkeiten moderner neurowissenschaftlicher Methoden bei gleichzeitiger Vernachlässigung der potenziellen negativen Folgen für das Individuum, für die Gesellschaften und insgesamt für unsere Spezies. Im gegenständlichen Überblicksbeitrag werden behaviorale, neuroelektrische und pharmakologische Methoden im Hinblick auf ihr aktuelles Potenzial einer Steigerung der individuellen Intelligenz analysiert. Die zwischenzeitlich zu diesen Fragen vorliegenden experimentellen Studien, sowie verfügbare Metaanalysen lassen allerdings den Schluss zu, dass bislang keine der gegenwärtig verfügbaren Methoden das Potenzial haben, die individuelle Intelligenz substanziell zu steigern. Und selbst falls solche möglicherweise in absehbarer Zeit zur Verfügung stünden, müssen zuvor sowohl individuelle als auch gesellschaftliche (negative) Konsequenzen einer kritischen Analyse unterzogen werden. Diese sind Gegenstand einer abschließenden Diskussion.

The Contribution of Personality and Intelligence Toward Cognitive Competences in Higher Education

Personality and cognition are found to be two interrelated concepts and to both have a predictive power on educational and life outcomes. With this study we aimed at evaluating the extent to which personality traits interact with cognition in acquiring cognitive competences during higher education. In a sample of university students at different stages of their career and from different fields of study, we collected Big Five traits, as a measure of personality, and Intelligent Quotient (IQ), as a proxy of cognition. A set of multiple regressions served to explore the relative contribution of IQ and personality traits on the performance on two cognitive competences tests: literacy and numeracy. Results showed that IQ highly modulated numeracy but had a moderate or no impact on literacy while, compared with IQ, personality affects literacy more. In a further explorative analysis, we observed that both the effects of personality and IQ on cognitive competences were modulated by the level of the students' career (freshmen, undergraduates, and bachelor graduates). Different traits, and particularly conscientiousness, increased or decreased their impact on achieved scores depending on the educational level, while IQ lost its effect in undergraduates suggesting that personal dispositions become more influential in advancing the academic carrier. Finally, the field of study resulted to be a predictor of numeracy, but also an important covariate altering the pattern of personality impact.

Mitochondrial Functions, Cognition, and the Evolution of Intelligence: Reply to Commentaries and Moving Forward

In response to commentaries, I address questions regarding the proposal that general intelligence (g) is a manifestation of the functioning of intramodular and intermodular brain networks undergirded by the efficiency of mitochondrial functioning (Geary 2018). The core issues include the relative contribution of mitochondrial functioning to individual differences in g; studies that can be used to test associated hypotheses; and, the adaptive function of intelligence from an evolutionary perspective. I attempt to address these and related issues, as well as note areas in which other issues remain to be addressed.

Does Blindness Boost Working Memory? A Natural Experiment and Cross-Cultural Study

Intelligence requires sufficient working-memory capacity. Traditionally, working memory was seen as a process and as a prerequisite for fluid intelligence. Working memory was assumed to be determined by maturation and health. There is a gap in the literature: It is still not fully understood to which extent and how working memory can be influenced. So this study tested how visual impairment and the extent of visual impairment are related to working memory capacity. In our study we compared N = 249 children (6–16 years) with and without visual impairment (blind, visually impaired, and sighted) in two countries (South Africa and Austria) at different development levels on their working-memory capacity and verbal comprehension. Using the WISC-IV, blind and visually impaired children showed higher working-memory capacity than sighted children (r = + 0.35, 14, and 3 IQ points, respectively). On the other hand, visually impaired children showed a weakness in verbal comprehension (r = −0.39, on average 13 IQ points lower). The pattern remained robust when SES and race-ethnicity were controlled. Our natural (quasi-)experiment shows a pattern, which is unlikely to be genetic, and so supports the view that working memory and intelligence scores can be modified.

Do Chinese Preschool Children Eat a Sufficiently Diverse Diet? A Cross-Sectional Study in China

BACKGROUND

This study aimed to comprehensively evaluate dietary diversity and its associated factors in Chinese preschoolers and explore whether the daily food consumption of children with different dietary diversity-associated characteristics met recommended dietary amounts.

METHODS

A cross-sectional study covering seven cities and two villages was conducted and included 697 preschool children aged 3⁻7 years old. Dietary diversity score (DDS) and DDS 10 were calculated based on 24-h dietary recall. The food-intake differences among children with different DDS 10 predictors were examined.

RESULTS

The mean DDS and DDS 10 in Chinese preschool children were 7.4 ± 1.5 (ranged from 3 to 9) and 7.0 ± 3 (ranged from 3 to 9) respectively. Positive predictors of dietary diversity included residing in an urban environment, a higher household expenditure on children’s food, and a higher frequency of eating outside. Food-intake differences existed among the predictors.

CONCLUSIONS

Education and intervention should be strengthened to improve the dietary diversity of preschool children, especially in rural areas. The overall dietary pattern of children requires attention, which means not only increasing dietary diversity but also avoiding an unbalanced diet.