INMA: “Socioeconomic position, family context, and child cognitive development”

A new study of the Gipuzkoa and Valencia cohorts of the INMA study reflects how socioeconomic position (especially social class) and family context (especially cognitive stimulation, stress management and parental profile) are related to lower scores on the test that evaluates cognitive development.

Cognitive development is the growth and maturation of thought processes. It is a continuous evolution that, according to the developmental psychology of Jean Piaget, begins with the sensorimotor stage (from birth to approximately 2 years of age) and ends with the formal operations stage (from 11 to 15-20 years), characterized by the beginning of abstract thinking and by the use and contrast of hypotheses. Socioeconomic position increases differences in children’s cognitive development. This has traditionally been estimated through social class, educational level or employment situation. In addition to the influence of socioeconomic position, events that occur within the family context in a stable basis could influence cognitive development, such as the habit of eating together sharing experiences, or relaxing with a story in bed before going to sleep.

The recently published work analyzed the role of socioeconomic position, measured through various indicators, in cognitive development evaluated between 7 and 11 years of age, studying the role of the family context as a potential mediator. Indicators of socioeconomic position were evaluated during pregnancy (family social class, parental education, employment and disposable income) and at 7 (Gipuzkoa) and 11 (Valencia) years (At Risk of Poverty or Social Exclusion (AROPE)). Family context and cognitive development were measured with the Haezi-Etxadi Family Assessment Scale 7-11 (HEFAS 7-11) and Raven’s Colored Progressive Matrices (Raven’s CPM), respectively.

The socioeconomic position variable that was best related to cognitive development was family social class, showing that those households belonging to lower social classes had children who obtained lower cognitive scores. The indicators of socioeconomic position were related to subscales of the family context, particularly those related to cognitive stimulation, stress of mothers and fathers, and raising children. This indicated that households with more disadvantaged positions also presented worse scores on the family context scales. In this study it was found that part of the relationship between social class and cognitive development was explained by the family context. When the subscales were taken into account separately, they influenced between 5 and 11% on the relationship, while the percentage was 12% when they were taken into account as a whole.

Both socioeconomic position and family context contribute to children’s cognitive development. Equalizing policies and positive parenting programs could contribute to improving the cognitive development of children

Reference: González L, Popovic M, Rebagliato M, Estarlich M, Moirano G, Barreto-Zarza F, Richiardi L, Arranz E, Santa-Marina L, Zugna D, Ibarluzea J, Pizzi C. Socioeconomic position, family context, and child cognitive development. Eur J Pediatr. 2024 Mar 14. doi: 10.1007/s00431-024-05482-x. Epub ahead of print.

Link to scientific article: https://link.springer.com/article/10.1007/s00431-024-05482-x

INMA: “Prenatal and child vitamin D levels and allergy and asthma in childhood”

An INMA study shows that having higher vitamin D levels at pre-school age might be related with a lower chance of eczema in childhood. A recent study by Sangüesa et al. used data from the INMA-Asturias, Gipuzkoa, Menorca, Sabadell, and Valencia cohorts to evaluate the relationship between vitamin D levels and allergy and asthma in childhood.

The prevalence of vitamin D deficiency can be up to 75% in adults, even in Southern European countries where there is a lot of sunshine. Pregnant women and infants in particular are at an increased risk. Vitamin D is important for the development of the immune system, and a deficiency can be linked to allergy and asthma in childhood. While most previous studies only look at allergic and asthma symptoms at one time point, this study goes a step further by examining the effect of vitamin D levels during both pregnancy and childhood.

The current investigation used information on vitamin D levels recorded during the INMA study, during pregnancy for around 2500 participants and at 4 years of childhood for around 800 participants. Answers from questionnaires collected between 1 to 9 years were used to determine whether the child had: allergic rhinitis, atopic eczema, wheeze, and/or asthma.

Around 19% of mothers and 24% of children had a vitamin D deficiency. The study concluded that having a higher vitamin D level at a pre-school age was associated with a smaller chance of having eczema during childhood. Also, having a higher vitamin D level during pregnancy and childhood might lower the chance of late-onset wheezing.

The study builds on existing literature relating to the possible positive effect of vitamin D levels in children of pre-school age on atopic eczema. This could be because vitamin D plays a role in preventing inflammation responses and infections. However, the authors highlight the importance of further studies to evaluate vitamin D levels during pregnancy and childhood, and their relationship with allergic and asthma symptoms later in childhood.

Reference: Sangüesa J, Sunyer J, Garcia-Esteban R, Abellan A, Esplugues A, Garcia-Aymerich J, Guxens M, Irizar A, Júlvez J, Luque-García L, Rodríguez-Dehli AC, Tardón A, Torrent M, Vioque J, Vrijheid M, Casas M. Prenatal and child vitamin D levels and allergy and asthma in childhood. Pediatr Res. 2023 May;93(6):1745-1751.

Link to scientific article: https://pubmed.ncbi.nlm.nih.gov/36057646/

INMA: “Social inequalities, green and blue spaces and mental health in 6–12 years old children participating in the INMA cohort”

An exciting new study has used the INMA cohort to investigate how living near to green and blue spaces affects people’s mental health. While there is existing evidence to suggest that access to the natural environment is beneficial for mental health, this new study went further by investigating the potential impact of socio-economic status (SES) on this relationship. This is an important consideration because there is evidence that people from lower socio-economic backgrounds have less access to natural environment features, which may exacerbate existing inequalities.

Specifically, this study used validated questionnaires to determine the extent to which children from Asturias, Gipuzkoa, Sabadell and Valencia in Spain, internalize or externalize their perceived psychological problems, and also looked at four distinct symptom groups: emotional problems, conduct problems, hyperactivity and inattention, and peer problems. The authors used two quantitative measures of proximity to natural environment features, namely, the normalised difference in vegetation index (NDVI) and whether or not the person has green space (such as a park) within 5km of their home. The SES for the specific areas in which people live was calculated using a validated index that is based on unemployment, the proportion of manual workers, people in temporary work, low-levels of educational attainment, and low-levels of educational attainment in young people.

The study found no clear difference in the relationship between mental health conditions and natural environment features between levels of SES, although children whose mothers graduated from secondary school consistently had lower internalizing and externalizing scores than children whose mothers had a highest educational level of primary school.

This new study did not identify an association between green and blue space and internalizing and externalizing problems. This finding is consistent with a recent systematic review on the subject. The authors of the new study hypothesised that this may be due differences in the association between subgroups of the population, hence the investigation by different levels of SES. Analysing subgroups according to SES, however, did not show a statistically significant association between green and blue space and internalizing and externalizing problems.

While the study didn’t find associations between SES and the relationship between mental health and access to the natural environment, it found some evidence to suggest that proximity to natural environment features alone was influenced by SES. These were not always in the expected direction though, for example while children in the lowest SES band had lower levels of vegetation than those in the highest SES band according to the NDVI score, they actually had higher levels of access to major green space. Other studies have reported that there may be a difference in the quality of these green spaces, but this was outside the scope of the current study.

The authors concluded that while this study did not identify statistically significant associations between mental health and the natural environment by levels of SES, there are grounds for further investigation. They suggested that future investigations may benefit from measuring the amount of time individuals spend in natural areas, rather than just their access to them, and also the quality of the natural spaces. All in all this study contributed to the existing literature by providing additional evidence of the factors that may or may not influence mental health in children

Reference: Subiza-Pérez M, García-Baquero G, Fernández-Somoano A, Riaño I, González L, Delgado-Saborit JM, Guxens M, Fossati S, Vrijheid M, Fernandes A, Ibarluzea J, Lertxundi N. Social inequalities, green and blue spaces and mental health in 6-12 years old children participating in the INMA cohort. Health Place. 2023 Sep;83:103104.

Link to scientific article: https://doi.org/10.1371/journal.pone.0283799

INMA: «An INMA Study Investigates Cardiometabolic Patterns in Childhood»

Over the past decade, there has been a concerning increase in the prevalence of disorders such as obesity, hypertension, dyslipidemia, and hyperglycemia, all of which are key risk factors for cardiovascular diseases. These disorders tend to cluster and appear simultaneously in adults, significantly elevating the risk of type 2 diabetes and other cardiovascular diseases.

During childhood, obesity has experienced a notable rise, with scientific evidence indicating that early obesity can persist into adulthood. Despite these observations, previous studies on the tendency of cardiometabolic factors to cluster in childhood have yielded diverse results.

The new study, conducted in the INMA cohort in Asturias, aimed to explore the simultaneous presence of multiple cardiometabolic risk factors, including obesity, hypertension, dyslipidemia, and hyperglycemia, at ages 4 and 8. A total of 332 children were examined through clinical assessments to evaluate their metabolic health, measuring waist circumference, systolic and diastolic blood pressure, blood glucose levels, and levels of triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) in the blood.

The results reveal that, at both 4 and 8 years old, the most common patterns are the absence of risk factors and the isolated presence of central obesity. At 8 years old, the isolated presence of hypertension is also observed. Although these are the most prevalent patterns, it was noted that central obesity tends to appear simultaneously with other risk factors at both ages, highlighting its relevance in the development of additional cardiometabolic conditions.

A significant finding is that almost all children without risk factors at 4 years old continued to be free of them at 8 years old, suggesting that maintaining good cardiometabolic health in childhood can have a protective effect over time. This study underscores the importance of addressing metabolic health from early ages to prevent cardiovascular risks in the future.

Reference: Fernández-Iglesias R, Fernández-Somoano A, Rodríguez-Dehli C, Venta-Obaya R, Riaño-Galán I, Tardón A. Cardiovascular risk factors and its patterns of change between 4 and 8 years of age in the INMA-Asturias cohort. PLoS One. 2023 Apr 12;18(4):e0283799.

Link to scientific article: https://doi.org/10.1371/journal.pone.0283799

INMA: “Short- and medium-term air pollution exposure, plasmatic protein levels and blood pressure in children”

Air pollution is one of the well-known key contributors to the global burden of mortality and disease. Nowadays, approximately 91% of the worldwide population lives in places where the levels of air quality exceed the guideline limits established by the WHO (World Health Organization, 2021).

Among the different harmful air pollutants affecting human health, some have been highlighted given their potential direct effects in the incidence of cardiovascular disease; such as particulate matters (PMs) of different sizes (PM2.5 and PM10), nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO) and ozone (O3). According to recent evidences gathered in adults, the effects of these pollutants on cardiovascular health could be mediated through the elevation of blood pressure levels. However, not much is known about the exact underlying biological and molecular mechanisms. Additionally, evidence regarding to which extent the harmful effects of air pollutants on blood pressure levels occur during early stages of life is still scarce. On the other hand, this type of knowledge is of critical importance since exposure to environmental hazards during childhood might permanently change the body’s structure, metabolism, and physiology, marking the cardiovascular health of future populations.

In order to shed some light to these open questions, INMA researchers have conducted what is one of the first studies evaluating the influence of air pollution exposure on blood pressure, and attempted to elucidate the most plausible biological mechanisms underlying such connections, all in the context of early childhood.

To do so, different time windows of exposure to various air pollutants (1-day, 1-week, and 1-year) and the levels of thirty-six different cytokines, apolipoproteins, adipokines, and other proteins were measured in 1170 children aged 6–11 years (in which INMA represents one among five other cohorts), mapping their relationship with blood pressure alterations.

Among the most remarkable results, they found a potential effect of exposure to some of the analyzed pollutants (NO2, PM10, or PM2.5) on the levels of proteins such as the hepatocyte growth factor (HGF) and interleukin 8 (IL8), showing higher concentrations in those children living in more polluted environments. These findings are in line with previous evidence in adults showing that the adverse health effects of air pollution could come from the exacerbation of harmful molecular processes such as oxidative stress and systemic inflammation.

Interestingly, this study could further connect the exposure to NO2 with higher levels of systolic blood pressure, reaffirming in children what previous investigations have shown in adults. Furthermore, the mediation study suggested that HGF could explain 19% of the short-term effects of NO2 on blood pressure, thereby proposing specific molecular mechanisms that could underly the air pollutants-blood pressure relationship.

Despite the interest and novelty of these results, they have to be interpreted with caution, since, for example, the relationship between HGF and BP is still uncertain. HGF is not usually considered as an inflammatory marker, and was first described as a liver-regenerative circulating factor. It could possibly be a downstream product of increased blood pressure or a molecule excreted by the body in response to air pollution exposure to counteract the endothelial damage induced by hypertension. In any case, further studies are needed to continue investigating these hypotheses.

Overall, the findings presented in this study reinforce the idea of increased adverse cardiovascular effects as a result of air pollution exposure in children. Moreover, considering that elevated blood pressure during childhood has an impact on health across the lifespan, reducing the exposure to this environmental risk factor can be an important prevention strategy.

INMA-article summary written by Augusto Anguita-Ruiz, INMA researcher.

Reference: de Prado-Bert P, Warembourg C, Dedele A, Heude B, Borràs E, Sabidó E, Aasvang GM, Lepeule J, Wright J, Urquiza J, Gützkow KB, Maitre L, Chatzi L, Casas M, Vafeiadi M, Nieuwenhuijsen MJ, de Castro M, Grazuleviciene R, McEachan RRC, Basagaña X, Vrijheid M, Sunyer J, Bustamante M. Short- and medium-term air pollution exposure, plasmatic protein levels and blood pressure in children. Environ Res. 2022 Aug;211:113109.

Link to scientific article: https://pubmed.ncbi.nlm.nih.gov/35292243/

INMA: “Exposure to persistent organic pollutants during pregnancy may affect cardiometabolic health in preadolescents”

Prevalence of childhood obesity has been increasing in the past decade, and today 33% of the European children are considered overweight or obese. Childhood obesity is a major public health concern, since it has been linked to higher risk of adult obesity and poorer cardiometabolic health in later life.

Some persistent organic pollutants (POPs) are suspected to alter hormonal metabolisms and may affect human cardiometabolic health. POPs include organochlorine pesticides (e.g., p,p’-DDT, HCB, β-HCH), as well as industrial chemical (PCB). The production and use of these chemicals have been banned under the Stockholm Convention decades ago. However, due to their high persistence in the environment, they are still detected in human bodies, including pregnant women and children. Populations are mostly exposed by contaminated food. During pregnancy, maternal levels of POPs are transmitted to the child through the placenta, and postnatally, via breast milk.

In previous studies, prenatal exposure to POPs has been associated with a risk of elevated body mass index (BMI) and elevated blood pression in childhood. Nevertheless, few studies have investigated whether these associations persist into preadolescence. Also, previous literature has mostly assessed single POPs exposures and did not consider POPs exposure as a mixture.

The main objective of the study was to determine whether prenatal exposure to POPs could affect cardiometabolic health in preadolescents, using adiposity markers and blood pressure data from two birth cohorts in Europe.

A total of 1667 children from the INMA-Gipuzkoa, -Sabadell, -Valencia study (Spain) and the PELAGIE cohort (France) were included. POPs levels were assessed in maternal serum collected at 12 weeks of gestation and in umbilical cord serum, for the INMA study and the PELAGIE cohort, respectively. When children reached 11-13 years, clinical examinations were carried out to measure BMI, percentage of fat mass, abdominal obesity, overweight/obese status, and systolic and diastolic blood pressure.

The results suggest that higher prenatal exposure to POPs mixture was associated with higher BMI and body fat, and higher risk of being overweight/obese at preadolescence, with no evidence of sex difference. HCB was the main contributor to these effects, followed by β-HCH and p,p’-DDE. β-HCH and p,p’-DDE were also associated with higher systolic blood pressure, especially in girls.

Charline Warembourg, last author of the study, say that “these findings confirm that prenatal exposure to organochlorine pesticides is associated with an increased risk of obesity, until adolescence.” She adds that “it is necessary to study whether or not these effects persist in later life”.

Reference: Rouxel E, Costet N, Monfort C, Audouze K, Cirugeda L, Gaudreau E, Grimalt JO, Ibarluzea J, Lainé F, Llop S, Lopez-Espinosa MJ, Rouget F, Santa-Marina L, Vrijheid M, Chevrier C, Casas M, Warembourg C. Prenatal exposure to multiple persistent organic pollutants in association with adiposity markers and blood pressure in preadolescents. Environ Int. 2023 Jun 22;178:108056. doi: 10.1016/j.envint.2023.108056. Epub ahead of print. PMID: 37379720.

Link to scientific article: https://doi.org/10.1016/j.envint.2023.108056

INMA:”Bullying from a biopsychosocial perspective: A study of the INMA project integrates hormonal markers to the study of bullying”

A study conducted as part of the INMA cohort studied bullying from a biopsychosocial perspective, integrating biological variables such as hormone levels into bullying behavior.

Bullying is defined as a type of aggressive behavior that occurs in the school context and typically occurs during childhood and adolescence. Despite sharing the intentionality that also appears in aggressiveness, bullying presents two other characteristics that make it a unique behavior. These include the repetitiveness of the actions and the imbalance of power between the victim and the bully.

Bullying is currently considered a public health problem that affects about one third of students worldwide. Being involved in bullying situations during childhood and adolescence can have serious consequences in different spheres of a person’s life, both short and long term.

It is thus imperative to study the factors associated with bullying behavior to try to understand this phenomenon in its totality. The most recent research indicates that the origin of aggressive behavior is multi-causal and that it is influenced by biological, social, and cultural factors. Although human behavior in general has been studied from a psychosocial point of view, more and a growing body of research is attempting to focus on the study of biological factors. However, few studies have tried to explore the possible biological markers of bullying.

Regarding biological factors that influence behavior, previous research has focused on the role of hormones, specifically testosterone and cortisol, at two developmental periods. The prenatal and pubertal periods are two developmental stages sensitive to the effects that hormones have on the nervous system and therefore on behaviors dependent on brain structures altered by these hormones.

Based on all this, a study of the INMA project decided to explore bullying behavior from a biopsychosocial perspective, taking into account the effects that could have both social psychological variables and hormonal levels of preadolescents. The study was carried out with 302 preadolescents from the INMA project cohort in Gipuzkoa. When the preadolescents were 11 years old, information about bullying behavior was collected using a questionnaire. In addition, information on several psychological and social variables (executive function, family context, school context and social context) was collected by asking these pre-adolescents and their relatives. Data on prenatal and prepubertal hormone levels were determined by saliva samples and the 2D:4D ratio.

The results showed that 9.6% of the participants were involved as victims, 1.7% as bullies and another 1.7% as bullies/victims. The study found that only the bullying role in boys appeared to be influenced by both hormonal levels and psychosocial variables. Specifically, it was observed that lower prepubertal cortisol levels together with a poorer perception of the school environment and lower peer and social group support were associated with a higher risk of being involved in bullying situations as bullies.

The findings of this study are in line with what previous researchers have found in other studies. However, there is still limited evidence on the role of biological factors in bullying. Therefore, the study of bullying should continue to be approached from a biopsychosocial perspective. Identifying the hormonal levels that may affect this behavior, as well as the variables of interest from a more psychosocial aspect, we will be able to better profile those people who are vulnerable to being involved in this type of situation and also to develop bullying prevention and intervention programs in order to reduce its prevalence or the percentage of participants involved.

Reference: Babarro I, Andiarena A, Fano E, García-Baquero G, Lebeña A, Arranz-Freijo EB, Ibarluzea J. Do prepubertal hormones, 2D:4D index and psychosocial context jointly explain 11-year-old preadolescents’ involvement in bullying? Biol Psychol. 2022 Jul;172:108379. doi: 10.1016/j.biopsycho.2022.108379. Epub 2022 Jun 8.

Link to scientific article: https://www.sciencedirect.com/science/article/pii/S0301051122001223?via%3Dihub