Reviews Technology: Stress experienced during childhood alters brain

A lack of maternal love could develop a stress printed in the genes and disrupt the proper functioning of the brain. Although only demonstrated in rats, this finding may explain the predisposition of some people with neurological diseases.

Stress or anxiety are natural ways to alert the agency a danger, but some forms are chronic disease, as well as certain psychiatric and neurological diseases (such as schizophrenia or Parkinson's disease). These three diseases are linked to dysregulation of brain function, the common denominator being a neurotransmitter, γ-aminobutyric acid or GABA.

Like all neurotransmitters, it acts at the synapses, the intermediate region between two neurons. Instead of activating the neuron, the molecule inhibits GABA his excitement: it is an inhibitory neurotransmitter. Some molecules whose action is similar to that of GABA are used as anxiolytic or as drugs to reduce nerve activity and soothe the patient.

But what is the origin of chronic stress or schizophrenia, and why some persons are predisposed? According to psychologists, child left indelible marks and shapes the adults we become. It is now also the opinion of neurologists. Indeed, following the work of a team of McGill University in Montreal, the brain stores and built based on events surrounding the first moments of life.

Some genes are directly affected by stress and are no longer expressed. This is the case GAD1 gene, which disrupts brain function. © DR

The GAD1 gene is affected

To prove this, the researchers used an animal model. Different female rats were specially selected high for their particular behavior. Some had a maternal instinct overly protective towards their offspring, while others barely cared for their young. Raccoons early therefore had a special relationship with their mother, while others suffered from a lack of maternal affection.

According to the article published in The Journal of Neuroscience, analysis of gene expression from these pups showed that the GAD1 gene is turned off in those who lacked affection. This gene is necessary for the synthesis of the neurotransmitter GABA, the level of it is probably affected. In contrast, pups that received maternal excessive entourage express GAD1 gene in larger quantities.

The extinction of the gene is due to a phenomenon of epigenetic modification. In addition to the importance of the sequence of DNA that is responsible for production of functional proteins, chemical modifications to DNA (acetylation, methylation) will not alter the sequence but the expression level of genes. The enzymes that are normally recruited by DNA to synthesize messenger RNA are disrupted by the changes, no longer recognize the sequence and therefore do more work. The gene is then turned off until the changes are present.

Although the emotional gap that has lasted some time after birth, changes in gene expression GAD1 are preserved into adulthood, affecting brain function long term. This is the first evidence of a link between lack of maternal affection and the variation in the expression of a gene known to be linked to major human diseases.