After long debates about whether the appearance of diseases (including mental ones) is conditioned by genetics or by the environment, there is no longer any doubt. The two factors are involved and closely related.
If we refer to mental illness, we necessarily have to refer to the brain . An organ that is still quite unknown, which begins to form in early gestation and whose development can be altered by influences from its intrauterine environment (hormones, nutrient deficiencies, toxins …) and maternal living conditions (its most direct environment ).
Indeed, if the pregnant woman undergoes intense and continuous stress, she will have high levels of cortisol, the stress response hormone, which will cross the placenta. As a consequence of these high concentrations of cortisol, epigenetic changes will occur in the fetal brain (modifications in the areas of the DNA corresponding to certain genes, without altering their sequence) that will reduce the receptors responsible for facilitating the entry of cortisol into the cell interior. Consequently, plasma cortisol levels in the fetus will also remain high.
Maternal stress modifies the fetal brain
Various studies suggest that the children of women who have suffered intense stress during pregnancy have an abnormal response to stress . It manifests itself, among other things, in a greater reactivity of the newborn after the heel stick, with a slower emotional recovery. But also in the reaction of the infant and the older child to stressful situations, for example after the administration of a vaccine, after bathing or after the separation of the parents. In case there were doubts, fetal epigenetic changes linked to maternal stress have been identified in cord blood of neonates, and in other cell samples in infants and older children.
To top it all, MRI studies show that the mother’s stress and anxiety during pregnancy structurally modify the fetal brain. Sometimes the limbic area is affected, with an increase in the volume of the amygdala, that is, the brain area related to processing and emotional memory, mainly of negative emotions such as fear and anger. In parallel, maternal stress seems to cause a decrease in the hippocampus, the region responsible for memory and learning of affectively conditioned events.
Other modifications observed have been the reduction of gray matter in the prefrontal cortex, responsible for executive functions such as decision-making or self-regulation of behavior. To which are added changes in the structure of the white matter, which is responsible for connecting different brain areas with each other.
The epigenetic and structural changes produced will have exaggeratedly intense responses to stressful situations in the future lives of these children. They can even increase the probability of suffering from mental problems, which will manifest as emotional difficulties (exaggerated introversion, difficulties in social relationships …) or behavior (impulsivity, hyperactivity, aggressiveness …).
In the long run, all this can lead to an increase in conflict in the family, educational and social spheres. There are even studies that link the high stress experienced in pregnancy with a lower IQ, autism and schizophrenia in the offspring.
Childhood is decisive
After birth, the child’s brain continues to develop. At this stage it depends on both your genetic endowment and the modulation caused by your experience. And, in the same way that fetal life affected him through his mother’s experience, adverse experiences in the first years of life can excessively or prolonged stress response systems. If that happens, there are damaging effects on learning, behavior and health that will carry you through your entire life.
What are those adverse early life experiences that affect mental health as you grow up? Neither more nor less than abuse / neglect, domestic violence (mother victim of gender violence), mental illness of the parents, poverty, drug use by the parents, as well as the fact of suffering from a serious illness.
Children living in poverty generally experience more adversity, as they tend to face various factors that condition brain development. Namely: nutritional problems, exposure to toxins, poorer prenatal maternal health, less cognitive stimulation of the family (linguistic interaction), parental stress and poor parenting skills.
Research that has delved into the consequences of experiences of poverty and abuse in the first years of life have shown that, as occurred in fetal life, epigenetic changes occur in the infant brain that lead to greater reactivity from cortisol to stress.
Regarding the structural changes of the brain, they would be affected:
a) the amygdala, which becomes hypertrophied and overactive, resulting in anxiety;
b) the hippocampus, which suffers a decrease in size due to the loss of neurons and neuronal connections, causing deterioration in memory, mood control, and learning difficulties;
c) and the medial prefrontal cortex, related to the control of language and cognitive processes, including reasoning and planning, which decreases in volume and activity.
To make matters worse, with childhood adversities the connections between the prefrontal cortex and the amygdala deteriorate, which translates into loss of control over the limbic region.
Guarantee mental well-being in childhood
Although many questions remain to be answered, scientific advances leave no doubt about the intimate dependence between brain development in the first years of life and the social circumstances in which one grows up. For this reason, it seems a priority to ensure basic psychosocial conditions that guarantee that women experience their pregnancy in the best state of mental well-being.
For children who have lived through difficult circumstances from the first years of their life there is also hope. Both epigenetic modifications and structural changes in the brain are reversible due to the “plasticity” of the brain. Of course, they are only reversed if external conditions change. Hence the great social responsibility of putting means to prevent the damage or if not, at least intervene to reduce it when it is already present.
Author: Mª Dolores Estévez González. Pediatrician. Professor of the University School- Faculty of Health Sciences ULPGC, University of Las Palmas de Gran Canaria.
This article was originally published on The Conversation under a Creative Commons License. You can read the original article here .
Photo | iStockphoto
In Babies and more | Play with your baby! By playing together, their brains synchronize and begin to “communicate” with each other.
