Environmental and Genetic Factors Influence on the Brain

this slide describes how we think and understand about mental disorders today some of the information that I’m going to share with you in five or ten years will not be acceptable but that’s okay because the purpose of science is to do our best to understand this world and sometimes as our understanding matures based on science we have to change the way we think we know that mental disorders are caused by a combination of genetic factors and environmental factors and we know that both of them interact on the brain to create the probability the individual will develop a mental disorder or may not develop a mental disorder this creation of probability happens at the time of conception when part of the new individual’s DNA is inherited from the mother and part of the individuals DNA is inherited from the father and frankly it’s the look of the genetic dice what parts you get from which parent you may have mental disorder running in the family on your mother’s side but you don’t inherit that probability you may have a mental disorder running on your father’s side of the family but you don’t inherit that probability or you may you may inherit one or the other or both so again it’s really the role of the genetic dice the second thing however is the environment in utero and this environment really matters and that is why we try to provide the best perinatal care we can for women to improve optimization of the intrauterine and Ireland because stressors which means anything outside of the brain affecting the brain that come into the developing brain in utero can have a major impact on how that child’s brain grows and develops some of the stressors are obvious alcohol can lead to fetal alcohol syndrome severe protein malnutrition may increase the risk for schizophrenic illness different viruses so the list is pretty long and it’s really important that as much as possible a healthy womb environment be provided to all women the second part of this interaction occurs during the birth process anoxia that means a lack of oxygen to the brain if it affects the motor cortex that part of the brain that controls your movement can be obvious cerebral palsy is the word that we use to describe that but if that lack of oxygen affected the parts of the brain that control mood or or control different emotional states it may not be that obvious and the next phase in this development is the early developmental years those first few years of life are characterized by incredible brain development and environmental changes that occur during this time of life can sometimes not always but sometimes push brain development in one way or push it into another way but here it’s not just the environment either it’s also the genetics plus the environment so some people may be exquisitely sensitive to they’re in Germans and other people much less so sensitive to their environments so two people both put into exactly the same environment may have different outcomes the point is is that we at this time don’t know how to identify which people will be more or less responsive to negative impacts in their early years so our task is to try to provide the optimal environments that we can for all young people because as we see here in the Maritimes a rising tide lifts all boats the next big phase of brain development is during the adolescent years and here again environmental factors and genetic factors interact with each other and challenges in brain development that may have occurred earlier in utero or during birth or in those first few years of life may become manifest during the adolescent years where we didn’t see them before and that can be because of the rapid changes in brain growth and development that occur during the adolescent years things such as pruning of parts of the brain of receptors that are no longer needed also it can also it can be the impact of the genetics that show themselves at that time of the developmental cycle so let me go back to pruning if there is a genetic basis to pruning and there is you may have inherited a gene that prunes your brain effectively and efficiently or you may have inherited genes that don’t prune the brain effectively and efficiently which could lead to mental disorders and again it’s this combination of different environmental factors and different genetic factors all the way through the lifespan which increased the probability or decrease the probability for the onset of a mental disorder because just as negative life factors can perhaps push the probability in one direction positive life factors can perhaps push the development into another direction so as a result of this complex interplay a young person may end up with no mental disorder none whatsoever another person may end up with some signs and symptoms but not half the disorder and a third person may end up with the disorder cultural factors have a tremendous impact not on the creation of mental disorders but on how signs and symptoms are expressed so for example when I’m working in sub-saharan Africa with young people who have psychosis they will often have a delusional system they will incorporate culturally important components into that system witchcraft for example if I’m seeing patients at the iwk Hospital here in Halifax they don’t have that same component although they may have a delusional system they’re much more likely to think that someone has implanted an electrode into their brain and that the FBI or the CIA or some organization such as that is controlling how they think so in a nutshell the probability of mental disorders is on the basis of genetic endowment and environmental influences that begin from the time of conception and continue throughout our entire lifespan

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