Kids with Kidney Disease Likely To Experience Lower IQ and Educational Outcomes Into Adulthood Interview with:

L-R: Kerry Chen, Anita van Zwieten, Madeleine Didsbury, Germaine Wong

L-R: Kerry Chen, Anita van Zwieten, Madeleine Didsbury, Germaine Wong

Dr. Kerry Chen
Centre for Kidney Research, The Kids Research Institute
The Children’s Hospital at Westmead, Sydney School of Public Health,
The University of Sydney
Sydney, New South Wales, Australia What is the background for this study?

Response: Chronic kidney disease is a major public health issue, with end-stage disease often requiring a combination of complex medication regimens, dialysis and/or transplant surgery. In children, the major causes of CKD are genetic and congenital. The consequences of CKD in children can be long-term and debilitating especially as they transition into adulthood, affecting their physical, intellectual and emotional well-being.

To better understand these changes, the Kids Health and Wealth Study (KCAD) is the largest longitudinal cohort study of children and adolescents with CKD in Australia and New Zealand. Spread across 5 paediatric nephrology centres so far, the KCAD Study takes a life-course approach to collecting and analysing data pertaining to the interactions between reduced renal function and associated clinical, socio-economic, quality of life, psychological, cognitive and educational outcomes in children, especially as they progress in CKD stage and also as they transition into adulthood.

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First Signs of Psychotic Disorder May Appear in Childhood With Drop in IQ Interview with:
Josephine Mollon PhD
Department of Psychosis Studies, Institute of Psychiatry, Psychology, and Neuroscience
King’s College London, London, England
Currently with the Department of Psychiatry
Yale University School of Medicine
New Haven, Connecticut What is the background for this study?

Response: Psychotic disorders, such as schizophrenia, are severe mental disorders that cause a range of abnormalities in perception and thinking. Individuals with psychotic disorders also experience severe impairments in IQ and there is evidence that these impairments begin many years before hallucinations and delusions first appear. Understanding how and when individuals with psychotic disorder experience a drop in IQ scores will help us better predict and treat poor cognition in these individuals, and perhaps even the disorder itself.

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Genetic Expression of Intelligence Influenced By Environment, Especially in Childhood

“Reading is fun!” by Isaac Wedin is licensed under CC BY Interview with:
Bruno Sauce, PhD and
Louis D. Matzel, PhD
Department of Psychology, Program in Behavioral and Systems Neuroscience
Rutgers University
New Jersey, USA What is the background for this study?

Response: Scientists have known for decades that intelligence has a high heritability, which means that much of the individual differences in IQ we see in people are due to genetic differences. Heritability is a value that ranges from 0.0 (meaning no genetic component) to 1.0 (meaning that the trait is completely heritable). For example, the heritability of breast cancer is estimated at 0.27; the heritability of body mass index is 0.59; and the heritability of major depression is 0.40. In comparison, the heritability of IQ is estimated to be as high as 0.8 – quite a high value!

More recently, however, there have been studies showing that intelligence has a high malleability: the studies cover cognitive gains consequent to adoption/immigration, changes in IQ’s heritability across life span and socioeconomic status, gains in IQ over time from societal and scientific progress, the slowdown of age-related cognitive decline, the gains in intelligence from early education, differences in average IQ between countries due to wealth and development, and gains in intelligence that seem to happen from working memory training.

Intelligence being both highly heritable and highly malleable is seemingly paradoxical, and this paradox has been the source of continuous controversy among scientists.

Why does it matter? Because IQ predicts many important outcomes in life, such as academic grades, income, social mobility, happiness, marital stability and satisfaction, general health, longevity, reduced risk of accidents, and reduced risk of drug addiction (among many other outcomes). A clear understanding of the genetic and environmental causes of variation in intelligence is critical for future research, and its potential implications (and applications) for society are immense.

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Breastfeeding May Not Be Important For Children’s IQ

Sophie von Stumm BSc MSc PhD Department of Psychology Goldsmiths University of London London, United Interview with:
Sophie von Stumm BSc MSc PhD
Department of Psychology
Goldsmiths University of London
London, United Kingdom

Medical Research: What is the background for this study?

Dr. von Stumm: At the Hungry Mind Lab (, which I direct, we study individual differences in lifespan cognitive development. In particular, I am interested in factors that influence change in cognitive ability and knowledge. One such factor is breastfeeding, which some previous studies suggested to be associated children’s intelligence and IQ gains while others failed to find a relationship.

Medical Research: What are the main findings?

Dr. von Stumm: For this study, which was published last week in PloS One (link:, data were analyzed from more than 11,000 children born in the UK between 1994 and 1996. The children had been repeatedly assessed on IQ: the first time they were tested on intelligence at age 2, and then again repeatedly throughout childhood, overall 9 times, until the age of 16 years. We found that having been breastfed versus not having been breastfed was not meaningfully associated with children’s IQ differences at age 2 and also not with differences in children’s IQ gains until age 16. That is not to say that breastfeeding may not have other benefits for children’s development but our study strongly suggests that breastfeeding is not important for children’s IQ.   Continue reading

Longer Breastfeeding Not Linked To Higher Childhood IQ

Sabine Roza MD Ph.D. Department of Child and Adolescent Psychiatry & Psychology Department of Psychiatry, Erasmus MC, Rotterdam, The Netherlands.

Sabine Roza MD Interview with:
Sabine Roza MD Ph.D
. and
Ayesha Sajjad MD, Phd student
Department of Child and Adolescent Psychiatry & Psychology
Department of Psychiatry, Erasmus MC,
Rotterdam, The Netherlands.

Medical Research: What is the background for this study? What are the main findings?

Dr. Roza: WHO guidelines recommend six months of exclusive breastfeeding followed by partial breastfeeding until two years for overall optimum growth and development of children. However, the role of breastfeeding duration on child cognitive development remains a topic of continual debate. Previous research has shown mixed results on the role of breastfeeding duration and exclusivity on child IQ. Several methodological differences in study design inhibit comparisons of these studies and thus limit their generalizability. Furthermore, the association of breastfeeding with child cognitive development is subject to confounding by various factors especially maternal IQ. Therefore, we aimed to study the association between breastfeeding duration and breastfeeding exclusivity with non-verbal IQ in children. We used data the Generation R Study, which is a prospective cohort study from fetal life until young adulthood. Due to the large variability in ethnic backgrounds in our study participants, we focused on non-verbal IQ. In a large sample of 3761 children aged on average 6 years, we found an initial advantage of 0.32 points in non-verbal IQ for every increasing month of breastfeeding, which strongly attenuated after adjustments were made for child factors, maternal factors, sociodemographic factors, parental lifestyle and maternal IQ. Similar attenuation of effect sizes was observed for breastfeeding duration as a categorical variable and duration of exclusive breastfeeding.

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