[Article Review] How Very Preterm Birth or Very Low Birth Weight Impacts Intelligence in Adulthood

Reference

Eves, R., Mendonça, M., Baumann, N., Ni, Y., Darlow, B. A., Horwood, J., Woodward, L. J., Doyle, L. W., Cheong, J., Anderson, P. J., Bartmann, P., Marlow, N., Johnson, S., Kajantie, E., Hovi, P., Nosarti, C., Indredavik, M. S., Evensen, K.-A. I., Räikkönen, K., Heinonen, K., Zeitlin, J., & Wolke, D. (2021). Association of very preterm birth or very low birth weight with intelligence in adulthood: An individual participant data meta-analysis. JAMA Pediatrics, 175(8), e211058. https://doi.org/10.1001/jamapediatrics.2021.1058

Review

In this article, Eves et al. (2021) assessed the differences in adult IQ between individuals born very preterm (VPT) or with very low birth weight (VLBW) and term-born individuals. The authors conducted a systematic review of published data and a meta-analysis of individual participant data (IPD) from cohorts in two consortia (RECAP and APIC). The study included 2135 adults (1068 VPT/VLBW and 1067 term-born participants) born between 1978 and 1995.

The researchers found that VPT/VLBW participants had mean adult IQ scores that were 0.78 SD lower than term-born participants, equivalent to a difference of 12 IQ points. Among VPT/VLBW participants, lower gestational age, lower birth weight z scores, the presence of neonatal bronchopulmonary dysplasia or any grade of intraventricular hemorrhage, and lower maternal educational levels were all significantly associated with lower IQ scores in adulthood.

The findings from this IPD meta-analysis provide valuable insights into the factors associated with lower adult IQ in individuals born with VPT or VLBW. The study emphasizes the importance of addressing neonatal morbidities and maternal educational levels as potential interventions to improve long-term cognitive outcomes for this population.

[Article Review] Uncovering the Impact of Cannabis on Youth IQ: A Comprehensive Review

Reference

Power, E., Sabherwal, S., Healy, C., O'Neill, A., Cotter, D., & Cannon, M. (2021). Intelligence quotient decline following frequent or dependent cannabis use in youth: a systematic review and meta-analysis of longitudinal studies. Psychological Medicine, 51(2), 194-200. https://doi.org/10.1017/S0033291720005036

Review

In their recent study, Power et al. (2021) aimed to investigate the relationship between frequent and dependent cannabis use among youth and subsequent decline in Intelligence Quotient (IQ). The authors conducted a systematic review and meta-analysis of cohort studies that included pre- and post-exposure measures of IQ in non-treatment-seeking samples.

The authors searched Embase, PubMed, and PsychInfo databases from their inception until 24 January 2020, and pre-registered their review on PROSPERO (ID no. CRD42019125624). A total of seven cohort studies were identified, including 808 cases and 5308 controls. The studies were of moderate to high quality, and there was a low level of statistical heterogeneity (I2 = 0.2%) among them.

The results indicated a significant effect of frequent or dependent cannabis use in youth on IQ change, with a Cohen's d of -0.132 (95% CI -0.198 to -0.066) and p < 0.001. This translates to an average decline of approximately 2 IQ points following exposure to cannabis in youth. The authors suggest that future studies should include longer follow-up periods to assess the magnitude of developmental impact.

This study is an important addition to the literature on the effects of cannabis use on cognitive functioning and intelligence, particularly in young people. By providing a rigorous, systematic review and meta-analysis, Power et al. (2021) offer valuable insights into the potential negative consequences of frequent or dependent cannabis use on IQ and overall cognitive development.

[Article Review] White Matter Microstructure and Cognitive Performance: Insights from a Meta-Analysis in Schizophrenia

Reference

Holleran, L., Kelly, S., Alloza, C., Agartz, I., Andreassen, O. A., Arango, C., ... & Donohoe, G. (2020). The Relationship Between White Matter Microstructure and General Cognitive Ability in Patients With Schizophrenia and Healthy Participants in the ENIGMA Consortium. American Journal of Psychiatry, 177(6), 537-547. https://doi.org/10.1176/appi.ajp.2019.19030225

Review

Holleran et al. (2020) conducted a meta-analysis to explore the relationship between white matter microstructure and cognitive performance in patients with schizophrenia and healthy participants using data from the ENIGMA Consortium. The study included 760 patients with schizophrenia and 957 healthy participants from 11 sites. The authors used principal component analysis to calculate a global fractional anisotropy component and a fractional anisotropy component for six long association tracts. The results showed that higher fractional anisotropy was associated with higher cognitive ability. The study provides robust evidence that cognitive ability is associated with global structural connectivity, independent of diagnosis.

The authors noted that schizophrenia is associated with widespread white matter microstructural abnormalities, but the functional effects of these abnormalities remain unclear. This study contributes to the current understanding of the relationship between white matter microstructure and cognitive performance in patients with schizophrenia and healthy participants. The meta-analysis included a large sample size from multiple sites, and a common analysis pipeline was used, which enhances the validity of the results. The findings suggest that there is a more general, rather than disease-specific, pattern of association between fractional anisotropy and cognitive ability.

Overall, the study by Holleran et al. (2020) provides valuable insights into the relationship between white matter microstructure and cognitive performance in patients with schizophrenia and healthy participants. The findings suggest that cognitive ability is associated with global structural connectivity, and the association is independent of diagnosis. The study highlights the importance of investigating the functional effects of white matter microstructural abnormalities in schizophrenia to improve social and functional outcomes in patients.

[Article Review] Unlocking Potential: How Education Can Improve Intelligence

Reference

Ritchie, S. J., & Tucker-Drob, E. M. (2018). How Much Does Education Improve Intelligence? A Meta-Analysis. Psychological Science, 29(8), 1358-1369. https://doi.org/10.1177/0956797618774253

Review

In this article, Ritchie and Tucker-Drob (2018) explore the relationship between education and intelligence, specifically whether more education leads to increased intelligence. The authors conducted a meta-analysis of 142 effect sizes from 42 data sets, involving over 600,000 participants, using quasi-experimental methods including controlled associations, instrumental variables, and regression-discontinuity designs. The results reveal a consistent, positive effect of education on cognitive abilities, with an increase of 1 to 5 IQ points for each additional year of education.

The authors' robust analysis further highlights the durability of the observed effects, as they persist across various life stages and all broad categories of cognitive ability. This finding is significant, as it suggests that education is a consistent and reliable method for increasing intelligence. By using various research designs, Ritchie and Tucker-Drob (2018) strengthen the validity of their findings, making a compelling case for the importance of continued education in promoting cognitive development.

Overall, the study by Ritchie and Tucker-Drob (2018) offers valuable insight into the impact of education on intelligence, and its findings have important implications for policymakers and educators. The results underscore the significance of investing in education to promote cognitive growth, which can contribute to individual and societal success. This study lays a strong foundation for future research exploring the specific mechanisms through which education may enhance intelligence and cognitive abilities.

[Article Review] Unlocking Potential: The Impact of Growth Mind-Set Interventions on Academic Achievement

Reference

Sisk, V. F., Burgoyne, A. P., Sun, J., Butler, J. L., & Macnamara, B. N. (2018). To What Extent and Under Which Circumstances Are Growth Mind-Sets Important to Academic Achievement? Two Meta-Analyses. Psychological Science, 29(4), 549-571. https://doi.org/10.1177/0956797617739704

Review

In this article, the authors investigated the relationship between growth mindsets and academic achievement. The researchers conducted two meta-analyses to determine the strength of the relationship and the effectiveness of interventions designed to increase growth mindsets on academic achievement.

The first meta-analysis examined the correlation between mindsets and academic achievement, considering potential moderating factors. The second meta-analysis explored the effectiveness of growth mindset interventions on academic achievement, also taking potential moderating factors into account. The overall effects were found to be weak for both meta-analyses. However, the study did provide some support for the theory that students with low socioeconomic status or who are academically at risk could benefit from growth mindset interventions.

This research contributes to our understanding of the importance of growth mindsets in academic achievement. While the overall effects were weak, the findings suggest that targeted interventions for specific groups, such as students with low socioeconomic status or those academically at risk, may yield positive results. Future research should continue to explore the potential benefits of growth mindset interventions and identify additional factors that may influence their effectiveness.