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Developmental Trauma and the Role of Epigenetics View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by ChesterRep 18 RESEARCH HEALTHCARE Counselling and Psychotherapy Journal October 2016 DEVELOPMENTAL TRAUMA AND THE ROLE OF EPIGENETICS NIKKI KIYIMBA DEMONSTRATES HOW THE NEW FIELD OF EPIGENETICS PROVIDES FASCINATING INSIGHTS INTO THE DEBATE ABOUT THE RELATIONSHIP BETWEEN NATURE AND NURTURE RESEARCH 19 e are all familiar with the Hunger Winter’. Between the beginning critical windows for epigenetically ongoing ‘nature versus of November 1944 and the late spring of mediated developmental trauma. One nurture’ debate, as we strive 1945, there was a famine in Holland. of the reasons for this is that the most to understand how much Studies of individuals who were conceived significant opportunities for Wof human behaviour is predetermined during the famine indicated that they developmental plasticity occur during through genetic coding and how much of it were at increased risk of developing these periods, meaning that the child is the result of environmental influences. schizophrenia, depression, heart disease, is most susceptible to the impact of Epigenetics is a whole new phase of cognitive deficits and diabetes.6 These chemical or social stresses.9 biological science that demonstrates to studies showed that nutritional deprivation In addition to diet during pregnancy, us the influence of environmental factors in human mothers appeared to have a another well-researched area has been on the way that genetic DNA coding is significant impact on the children born the impact of maternal stress on the expressed. The word ‘epigenetics’ was following this period of deprivation. developing foetus. Fifty years of animal originally coined by Waddington1 in 1942, In order to understand how genes are studies have shown that maternal stress and literally means ‘on top of’ genetics. temporarily affected by such factors, we during pregnancy can have long-term Epigenetic changes are modifications of need to think briefly about the biological effects on the offspring, including DNA, which occur without any alteration processes involved. The two primary learning deficits, altered immune to the underlying DNA sequence, and can mechanisms that happen in epigenetics function, more anxious behaviour, control whether a gene is turned ‘on’ or ‘off’. are ‘histone modification’ and ‘DNA reduced attention, glucose intolerance Genetic expression therefore has been methylation’. In the first of these, the and altered cardiovascular responses to described using the metaphor of a light double helix of DNA strands are tightly stress. It is thought that cortisol crosses switch, as a gene is only activated when coiled around proteins called histones. the placenta and may affect the foetus ‘turned on’ by the environment.2 and disturb developmental processes. Waddington,3 who started his work by A review of the literature mostly suggests studying fruit flies, noticed that when that prenatal stress or anxiety is the flies were subjected to unusual associated with raised basal cortisol or circumstances, modifications occurred OFF raised cortisol reactivity in the offspring.10 at a genetic level in their wing structures. Encouragingly, some research has shown Although these changes were acquired that a mild degree of stress during the characteristics, he discovered that the prenatal period can actually increase the changes actually became assimilated by baby’s mental and motor development.11 the genotype. Importantly, unlike genetic However, it seems that higher levels of mutations, these genetic changes are stress during pregnancy can potentially potentially reversible.4 have a lasting adverse impact on the child. Some of the more recent experiments ON A few high profile studies of international in the field of epigenetics have been disasters, including 9/11,12 Chernobyl13 laboratory studies in which mice with the and a Canadian ice storm,14 have same genetic blueprint were exposed to examined the effects of acute stress on different environmental conditions. The pregnant mothers and the subsequent experiments were designed to examine It is the spacing between these histones impact on their children. Project Ice Storm the environmental impact on the DNA of that determines how well the DNA strand studied 89 children whose mothers were the mice. Even though mice with identical can be read. Where DNA strands are pregnant during a natural disaster that DNA were kept in exactly the same bunched together around histones, the occurred in January 1998 in the Canadian environment and fed on exactly the same DNA strands cannot be as easily read province of Quebec, which resulted in diet, some mice became larger and yellow as in the strands where histones are more power losses for three million people for coloured while other mice remained spaced out. In the second mechanism, up to 40 days. Findings indicated that smaller and darker coloured.5 The only chemicals called methyl groups attach children exposed to this maternal stress difference between the two sets of mice to DNA strands, thus blocking parts of during pregnancy had lower cognitive was in what their mothers ate during them from being read. Usually when and language abilities at five-and-a-half pregnancy. In the case of the healthier methylation of certain genes occurs, years of age compared to children of brown baby mice, the mother mice were those genes will be significantly limited mothers who had not been caught in given methyl donor food supplements (folic in their expression. the ice storm.13 acid, betaine, vitamin B12 and choline). Methylation of DNA is an integral These important studies have been quite epigenetic aspect of the development Clearly, in-utero stress can have a revolutionary in bringing epigenetics to and differentiation of cells, and can also detrimental impact on the physical, the forefront of our attention, by showing be the starting point of several diseases.7 cognitive and psychological development that maternal nutrition can have a huge Exposure to environmental stressors of the unborn child and may lead to impact on the physical development of such as pollutants, alcohol and tobacco behavioural problems or even the offspring, due to epigenetic influences. also has a detrimental impact on foetal development of mental illness. In addition 8 to natural disasters, there are also more This phenomenon has also been DNA programming. Research suggests common sources of antenatal stress. researched in humans. One of the classic that both the intrauterine environment studies was conducted following the ‘Dutch and early postnatal experiences are 20 RESEARCH HEALTHCARE Counselling and Psychotherapy Journal October 2016 One of these is the experience of domestic Essentially this means that what began as an important role in the way that the violence. Research focused specifically ‘acquired characteristics’ can sometimes hippocampus functions. There are on the impact of this, which was be inherited. It is possible that there is an several ways that plasticity occurs: conducted by Radke and colleagues,15 evolutionary benefit for intergenerational division (cell proliferation), selection indicated that there were epigenetic epigenetic transfer. For example, children (cell differentiation) and the maintenance modifications to the DNA of one of the of prenatally undernourished fathers were of new neurons (cell survival). While cortisol receptors in the children of found to be heavier or even obese in stress has the negative impact of mothers who had experienced comparison to children of fathers who had inhibiting neurogenesis by lowering cell interpersonal violence while they were not been undernourished.20 This study proliferation, there are simple practical pregnant. Specifically, they found that suggests that it may be an evolutionary ways to improve neurogenesis. Firstly, methylation of the glucocorticoid receptor quirk that means that, in some cases of physical exercise is known to activate to which cortisol binds was influenced deprivation, genetic modification is passed the hypothalamic–pituitary–adrenal axis by the mother’s experience of domestic on to future generations to better their (HPA axis) and increase glucocorticoid violence during pregnancy. chances of survival. levels, which in turn enhances neurogenesis. Other ways to improve neurogenesis are environmental Fifty years of animal studies have shown enrichment, learning and rewarding social experiences. For example, in cases of childhood maltreatment, that maternal stress during pregnancy environmental interventions in the form of social support may prevent can have long-term effects on the offspring, the development of depression.22 including learning deficits, altered immune Importantly, there are also those in the field of counselling and psychotherapy who are applying these advances in our function, more anxious behaviour, reduced understanding of the neurology of trauma to talking therapy. For example, Feinstein attention, glucose intolerance and altered and Church argue that counselling works on a neurological level by changing gene cardiovascular responses to stress expression and that ‘psychotherapeutic interventions … are effective in modulating the expression of genes’.23 There are many potentially traumatic The most optimistic aspect of this new One reason for their effectiveness may be events that can impact a child during their knowledge about how the environment the close interaction of emotions and gene early life. These are collectively
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