In this recent post by the HealthISglobal blog, Margarita Triguero, a PhD student at CREAL (now part of ISGLobal), gives us an overview about some recent studies showing the effects of natural spaces – mostly green spaces, both big and small – on health. As she says, blue spaces, such as lakes, rivers, or the sea, have been much less studied so far, but that’s about to change with a new international project called “BlueHealth Project“, which is led from the UK and in which the CREAL/ISGlobal researchers are involved.
Looking forward to hear more about this new project, which started earlier this year and will run until 2020! For the time being, you can read Margarita’s post here!
The group directed by Jordi Sunyer is part of the Research Centre for Environmental Epidemiology (CREAL) and focuses on three research lines, which are based on general population studies. While two junior scientists analyze the effect of pollutants on the respiratory system and hormonal disruption, the main research of Jordi Sunyer himself focuses on the neurological development of children.
To breastfeed or not to breastfeed
Sunyer, who is the co-director of CREAL and also the director of the epidemiology and public health programme of the IMIM, seeks to point out environmental factors to which the pregnant woman was or is exposed, that have an effect on children during pregnancy and after birth. The studies start with the collection of biological samples from pregnant women and from their offspring after birth and are continued with follow up studies for several years.
These analyses include the characterization of toxic substances which the mother might have accumulated long before pregnancy, and which she passes on to the child through breastfeeding like in the case of organochloride compounds. Despite of the negative effect of passing on these toxic compounds, the positive effects of breastfeeding is not under discussion, the scientist explains with a calming smile.
Naturally, the mothers’ diet also plays a critical role on the child’s development, as well as environmental pollutants she or the newborn child might encounter in their surroundings. Therefore, in addition to the analysis of biological material, geographical data are being collected. “We model the entire city and, according to the movements of the participants, we know what type of pollution they could have encountered”, Jordi Sunyer states.
Indoor and outdoor pollutants
Indoor pollutants comprise smoking, but also some combustion sources used in the homes. Measurements of NO2, which is a marker of several pollutants, reveal that children from households using gas have a poorer neurodevelopment than those from households where electricity is used. The former children perform worse in neuropsychological tests like the McCarthy test, which employs puzzles, verbal stimuli or computer performance to score attention, inattention or even hyperactivity. Sunyer further advises that in households employing gas as a combustion source, an extraction hood should be used, and that children ought to be banished from the kitchen while cooking, since then the above mentioned effects are no longer observed.
These early life exposures, which start already at conception, show that the described phenotypes cannot be explained exclusively by means of genetics, but that the environment does indeed play an important role. However, the group also does analyse the regulatory mechanisms at the genetic level, in collaboration with the group of Xavier Estivill at the CRG.
The silent pandemic
“Environmental air pollution probably is the major pollutant in the developed world”, says Sunyer. “It is everywhere and you can not avoid it. A group in Harvard even refers to it as the silent pandemic”. According to this group the curve of IQ or neurodevelopmental performance of the whole society is downshifting because of the polluted environment. As a consequence, the number of children with problems in school performance increases and this is also related to an increase in hyperactivity. Therefore, the scientist concludes, “understanding the effect of air pollution on child health is a major goal for our group”.
This article was published in the El·lipse publication of the PRBB.
An interview published in Ellipse, the monthly magazine of the PRBB.
Philippe Grandjean, Adjunct Professor of Environmental Health at Harvard University, delivered a lecture in Barcelona invited by Jordi Sunyer, from the CREAL, a ‘model institution’ according to Grandjean. Sunyer introduced the talk about what the Danish-born scientist calls a ‘silent pandemic’: the effect of chemical pollutants on neurodevelopment.
To what extent do in utero conditions affect adult health?
There are several studies that show that exposing pregnant women to mercury can affect the development of their children, even if they are not affected themselves. Minamata disease, a neurological syndrome caused in children whose mothers suffer severe mercury exposure, was discovered in Japan in the 1950s, and was a shock to the world. Since then many other studies have demonstrated the effect of mercury exposure on foetal development. However, it wasn’t until 2009 that an international agreement was reached to control mercury emissions into the environment!
How many pollutants can be neurotoxic during early development?
There are about 100,000 chemicals in the world. About 200 have been documented as being neurotoxic to adult humans, and only five to foetuses: lead, mercury, PCBs (polychlorinated biphenyls), arsenic and toluene. However, the foetal brain is much more sensitive than the adult one! So I think we are only seeing the tip of the iceberg. For example, many pesticides can be neurotoxic to humans, as the nervous system of the insects that the pesticides attack is very similar to ours. For example, we did a study in Ecuador on pregnant women working in flower plantations, who were exposed to pesticides. Their children at school age presented a delay of up to two years in their brain development.
Are these effects irreversible?
The brain has great plasticity, so one might think that with enough effort we could get kids with lower cognitive abilities to catch up with the rest. But the problem is for this plasticity to occur your neurones must be in the right place. You cannot develop your full potential if you don’t have the correct anatomical foundation and if your nerve cells and connections are abnormal.
And does mercury exposure cause anatomical problems in the brain?
Normally we have no way of checking, but with Minamata disease, quite a few of the children died, and when they were examined at autopsy it was seen that their brain cells appeared in a disrupted pattern, as if their migration during brain development had been affected. So yes, we think so.
If they are so dangerous, why are these pollutants not banned?
The problem is that chemicals are not banned unless it’s proven that they are dangerous. But then it’s too late! I think we need to move towards the opposite strategy: a chemical should be banned unless it is proven not to be dangerous to brain development. Prevention should come before science. After all, we have only once chance to develop a brain.
The developing brain is exceptionally sensitive to environmental inﬂuences, and two recent papers lead by scientists at the CREAL have analysed the effect of several variables – chemical exposure and social environment – in neurodevelopment of infants. In the specific cases studied, the effect didn’t seem to be very substantial.
One of the articles was published in the American Journal of Epidemiology, and it focuses on the potential effect of prenatal exposure to mercury, since it is known that vulnerability of the central nervous system to this metal is increased during early development. The scientists examined 1,683 children who are part of the INMA (Environment and Childhood) Project from 4 regions of Spain between 2003 and 2010. The mercury levels at the cord blood were analyzed by atomic absorption spectrometry, and infant neurodevelopment was assessed around age 14 months by the Bayley Scales of Infant Development – a standard series of measurements originally developed by psychologist Nancy Bayley and which are used to assess the motor, language, and cognitive development of children aged 0-3.
Although the maternal-birth cohort studied comes from moderate-high fish consumption areas, and mercury is found primarily in fish, even a doubling in total mercury levels did not show an association with mental or psychomotor developmental delay. When findings where stratified by sex, there was a slight negative association between prenatal exposure to total mercury and psychomotor development among female infants, but the researchers admit that follow-up is required to confirm these results.
The second paper, published in Gaceta Sanitaria, wanted to examine the effect of maternal intelligence and mental health, taking into account also maternal occupational social class and education, on the neuropsychological development of their children. The subjects studied were also from the INMA project and the children were, again, analysed at 14 months. The mothers’ intelligence and mental health were assessed by professional psychologists and standard tests and questionnaires.
The authors found that maternal IQ plays an important role in the ﬁrst stages of cognitive development in children in the more disadvantaged occupational social classes. For the other groups, the effects of maternal IQ on cognitive development were mostly explained by maternal education. As per maternal mental health, it had no effect on the childrens’ neurodevelopment, although the authors say this might be because the study was performed in a non-clinical population in which mothers were not suffering from any other serious depressive or psychiatric disorders.
Llop S, Guxens M, Murcia M, Lertxundi A, Ramon R, Riaño I, Rebagliato M, Ibarluzea J, Tardon A, Sunyer J, Ballester F, on Behalf of the INMA Project. Prenatal Exposure to Mercury and Infant Neurodevelopment in a Multicenter Cohort in Spain: Study of Potential Modifiers. Am J Epidemiol. 2012 Jan 27;
Forns J, Julvez J, García-Esteban R, Guxens M, Ferrer M, Grellier J, Vrijheid M, Sunyer J. Maternal intelligence-mental health and child neuropsychological development at age 14 months. Gac Sanit. 2012 Jan 26;
The Human Pharmacology and Clinical Neurosciences group of the IMIM-Hospital del Mar, lead by Rafael de la Torre, has published a paper in PLoS One this week to try to clarify the association between cumulative use of MDMA (ecstasy), one of the most popular illegal psychostimulants abused among youth, and cognitive dysfunction. They have also set to understand the potential role of candidate genetic polymorphisms in explaining individual differences in the cognitive effects of MDMA.
Several studies have suggested that MDMA induces neurotoxicity, which primarily affects the serotonin system and is linked to memory dysfunction. There is also evidence that several gene polymorphisms may contribute to explain variations in the cognitive impact of MDMA across regular users of this drug.
The research group took 60 ecstasy polydrug users, 110 cannabis users and 93 non-drug users and assessed them using several cognitive measures. Participants were also genotyped for polymorphisms within six genes. The scientists found that both MDMA lifetime use and gene-related individual differences influence cognitive dysfunction in ecstasy users.
According to the authors “this study reliably demonstrates dose-related effects of MDMA use on visual attention, organization and memory”.
Cuyàs E, Verdejo-García A, Fagundo AB, Khymenets O, Rodríguez J, Cuenca A, de Sola Llopis S, Langohr K, Peña-Casanova J, Torrens M, Martín-Santos R, Farré M, de la Torre R. The Influence of Genetic and Environmental Factors among MDMA Users in Cognitive Performance. PLoS One. 2011;6(11):e27206 [PDF]