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Post No.: 0156diathesis


Fluffystealthkitten says:


Inheritance matters when it comes to mental health i.e. both genetic and environmental inheritances, although (apart from in a limited number of cases i.e. Huntingdon’s disease, which is just about completely genetically penetrant or determined) scientists have yet to confidently identify which genes matter most because it’s likely to be the case that mental health involves lots of different genes, where each of which only contributes a tiny bit to the total outcome, but it all adds up. It likely also involves complex gene-environment interactions (GxE) and gene-gene interactions, as well as epigenetic influences (the expression of genes as a result of environmental/external factors or normal developmental programs as a person ages).


Genome-wide association studies (GWAS) are often used to look across the entire genome or genetic sequence to identify variations of the sequence that seem to be more common in people with particular mental health conditions. But the picture is complicated because, even though some variations more frequently present in those with a particular mental health condition than those without, these variations aren’t present in all sufferers of that particular condition, and these variations may even be present in some people who don’t have a mental health condition too, which means that there must be far more to it than just possessing those genes alone i.e. upbringing, life events and other environmental factors make a difference too.


Risk genetics (risky genes), in conjunction with a recent severe stressful or traumatic life event, is what vastly increases the risk of an episode of depression. The ‘diathesis-stress model’ shows that it’s a combination of the number of risk (‘bad’) genes compared to protective (‘good’) genes (one’s diathesis or predisposition), as well as the number and severity of risk (‘bad’) environments/events compared to protective (‘good’) environments/events (one’s stress or harmful life events), that complexly determine the overall risk and severity of depression for an individual. For example, a person who received enough ‘good’ happy, supportive, loving, quality times as a child, even if she/he experienced some truly ‘bad’ traumatic events as a child too, might, on balance with her/his ‘good’ and ‘bad’ genetics as well as other ‘good’ and ‘bad’ life events, end up fine as an adult; and vice-versa. For most mental health conditions, it’s down to this complex interacting combination of genetics and environmental factors.


We’ll know that if a person has a mental health condition, it must logically be something to do with her/his biology and history, according to the diathesis-stress model. But because we cannot run or compare parallel realities of people’s lives with subtle differences in input, it may be difficult or practically impossible to ever determine exactly what specific genes or events, or combinations of such, mattered most to a particular person’s outcomes. Nonetheless, everyone who suffers will have her/his causal reasons.


Someone with many risk alleles (variants of a given gene) but a low stress/high protective environment will likely be fine, but someone with few risk alleles but a high stress/low protective environment might suffer from anxiety. And of course, at the highest risk are those with many risk alleles and a high stress/low protective environment; and vice-versa. So, like lots of things to do with human psychology – having or experiencing one thing, such as having a certain gene or experiencing a certain traumatic event when young, doesn’t guarantee anything on its own – it depends on other factors too; but every little bit potentially adds up one way or the other (to increase or decrease one’s risks or protections). Something similar to chaos theory is perhaps at play i.e. although everything is behaving in a deterministic, cause-and-effect, context – the smallest differences in input could end up making quite large differences in output down the line, and since real life involves countless numbers of events and variables, any or maybe all of these events and variables (e.g. a single harsh moment of abuse or neglect, or conversely a kind and supportive word, that unconsciously stuck in the mind of a young person for life) could be having a sensitive and unpredictable effect on a person’s overall outcome well into adulthood?


So although research in this area is ongoing, mental health disorders seem to have a strong genetic component and so an increased risk or diathesis is genetically heritable – yet life events seem to play a large, possibly pivotal, role too – thus, for most conditions it seems, there is theoretically enough we can environmentally do, particularly during people’s upbringing/developing years, to protect everyone from developing a mental health disorder if we invest in this goal.


An analogy is like you right now definitely have risk genetics for skin that burns particularly easily when presented to a flame (the diathesis to burn), but your life and future prospects from hereon will be fine as long as no one pushes you into a fire or you don’t accidentally fall into a fire. Risk factors in the environment (e.g. a lot of careless cigarette smokers) will increase the chances of fires being started, and protective factors in the environment (e.g. tight and enforced fire safety buildings regulations) will protect your genetic disadvantages, even to the point that you may never ever experience a life-changing burn experience and hence your disadvantages of genetically possessing such fragile flesh becomes essentially a non-issue. Meow!


You could say that everyone should just watch out for themselves whether they (or their properties) will get burnt or not, but you surely welcome these protective measures in the environment that protect your genetic disadvantages too. So via ingenuity and/or collective cooperation, there is a lot of scope in improving the environment to make a lot of people’s genetic disadvantages essentially a non-issue. For example, if there’s an extensive accommodation for wheelchair users then wheelchair use essentially becomes virtually a non-issue, or if enough people understand sign language then being deaf is far less of a problem.


Mental health disorders are caused or exacerbated by a complexly interacting combination of genetics and environmental factors, and this environmental component of the diathesis-stress model includes how other people culturally treat each other in society as a whole, as well as how other people treat particular individuals; including those already with mental health conditions. So we’re logically all a part of each other’s problems and solutions – a part of each other’s risk and protective factors in the environment – when it comes to mental health outcomes (and other kinds of outcomes).


Meow. No person is an island entire of her/himself. I am in your environment and you are in my environment, I affect your health and you affect mine, hence we should look after each other and get along with each other.


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