Study Contradicts Diathesis-Stress Model of Psychosis

A new study found that as people experience more traumatic events, genetic risk becomes less important in explaining psychosis.

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Why do some people experience psychosis after trauma while others do not? A common theory to explain this is known as the “diathesis-stress model.” According to the theory, genetic risk (“diathesis”) primes a person to experience psychosis but requires traumatic events (the “stress”) to trigger the experience.

But now, a new study in the top-tier psychiatric journal JAMA Psychiatry has debunked the diathesis-stress model. The researchers found that genetic risk becomes less important as people experience more traumatic events.

This contradicts the assumptions of the model. In the diathesis-stress model, genetic risk should be more important when people experience trauma. Genetics is supposed to explain why, for two people who experience trauma, only one of them develops psychotic experiences. The researchers write:

“It is an important message that early manifestations of psychotic experiences during adolescence are not so strongly heritable, especially in the context of higher environmental exposure.”

Sad looking woman sitting at the tableIn contrast, the researchers suggest the bioecological model, which “posits that genetic factors become more pertinent in more favorable environments, leading to lower heritability in twin studies in the context of environmental exposure.”

Essentially, the researchers posit that genetics might help explain why some people who experience very little trauma develop psychosis.

“These results are consistent with a bioecological framework, which would predict that more favorable environments would lead to higher heritability,” the researchers write. “Our results run contrary to a diathesis-stress pathway to psychotic experiences, which would predict that environmental risks trigger a genetic susceptibility to a given disorder and would thus lead to higher heritability of a phenotype in the presence of environmental risks.”

The study was a combined effort, with Swedish researchers, including Mark Taylor at the Karolinska Institutet, Sebastian Lundström at the University of Gothenburg, and Henrik Larsson at Örebro University, and UK researchers, including Daniel Freeman at the University of Oxford and Angelica Ronald at Birkbeck University of London.

The researchers looked at twins in both the UK and Sweden to estimate the heritability of psychosis. Then, they correlated their findings with five environmental factors: bullying, number of “dependent life events” (a catchall term for experiences like a serious relationship loss or witnessing a crime), cannabis use, tobacco use, and low birth weight.

The researchers began by analyzing the data from the UK’s Twins Early Development Study (TEDS), in which the 4855 pairs of twins were, on average, 16.5 years old. They then also analyzed the data from the Child and Adolescent Twin Study in Sweden (CATSS), in which the 6435 pairs of twins were, on average, 18.6 years old.

Their first finding was that trauma was extremely predictive of psychosis. They write:

“More exposure to environmental risk factors was associated with having more psychotic experiences.”

This is consistent with previous studies that found that experiencing childhood trauma, not heritability, was associated with psychosis.

In this study, heritability became less important as environmental risk increased for the specific experiences of paranoia, cognitive disorganization, grandiosity, and anhedonia. However, for hallucinations and “negative symptoms,” heritability did not change based on environmental exposure.

The researchers note that the participants in their sample were young—teenagers—potentially having their first psychotic experiences. However, early psychotic experiences in young people are not rare and are transient in most cases (they do not lead to later diagnoses of schizophrenia or other psychotic disorders). Thus, this study, which captured these early experiences, may not be the best estimate of the heritability of full-fledged “disorders.”

In fact, for psychotic diagnoses like schizophrenia, it’s likely that the heritability is lower than that found by these researchers. Genetics studies have identified that genetic risk plays a minimal role in explaining schizophrenia, with a predictive power as low as 0.5%—indicating that 99.5% of the “cause” of psychosis is related to environmental factors, especially childhood trauma.

In the current article, the researchers add that a slight increase in the likelihood of schizophrenia compared to the general population is not very useful for prediction.

“Most relatives of individuals with schizophrenia do not develop schizophrenia,” they write.

They suggest that while having a family member with schizophrenia does increase the risk of psychosis for other family members; this could also be explained by a shared environment, not genetics.

A meta-analysis in 2021 debunked the main biological hypotheses promoted as potential causes of psychosis—the role of dopamine and glutamate—so even if heritability is involved in some way, it is unclear what biological pathway it would take.

In conclusion, the researchers write that environmental factors, like traumatic experiences, are far more important than genetics in explaining psychosis.

“To our knowledge, this twin study was the first with results that suggest that environmental factors play a greater role in the etiology of psychotic experiences than genetic factors.”

 

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Taylor, M. J., Freeman, D., Lundström, S., Larsson, H., & Ronald, A. (2022). Heritability of psychotic experiences in adolescents and interaction with environmental risk. JAMA Psychiatry. Published online August 3, 2022. doi:10.1001/jamapsychiatry.2022.1947 (Link)

24 COMMENTS

  1. The word “X” has meaning only if some things are not “X.” The word “diathesis” means “vulnerability to stress.” So are some people invulnerable to stress? Are there some people who could never meet the criteria for a diagnosis of schizophrenia, no matter how much stress and trauma and abuse they were subjected to?

    There is not an atom of evidence for that proposition, and if you think about it for a moment there couldn’t be. The definitive experiment in this case cannot be performed (thank God).

  2. Twin studies are pseudo-science anyway. As psychologist Jay Joseph has repeatedly pointed out, the entire field is based on an assumption which is demonstrably false — the equal environment assumption.

    A century of psychiatric genetics has not produced a single finding that has benefited a single patient anywhere in the world. It’s time to move on.

    We know the conditions needed for humans to thrive. It’s not rocket science. Let’s work on making those conditions available to everyone.

    • Plus genes are the one thing in the equation that we can’t ever change! Why spend billions studying genetics and getting tiny little ‘correlations’ from sets of hundred of genes, when we KNOW that certain environmental conditions will cause or exacerbate these problems and those CAN actually be changed?

      A great example is the so-called ‘ADHD’ child. It was shown in the 1970s that such children to incredibly much better in an open classroom, to the point that professionals can’t tell them apart from ‘normal’ children in that setting. Yet we spend tons of money promoting ‘genetic’ explanations that can never seem to be proven, instead of spending a lot less creating open classrooms as an option for kids who struggle in standard classroom settings.

      Sometimes I think the only reason they are so married to genetic explanations is because it lets the adults off the hook for trying to fix anything. ‘Oh, well, it’s just genetics, nothing we can do about it.’ Highly irrational!

      • I agree genetics are overrated but if mental illness is a response to environmental stress then from an evolutionary view rapid changes to society would create new stressors and new stress response. An example of this would be variable moods over the course of a year with periods of mania during resource rich times and depressed activity when resources are scarce. This was tremendously helpful for thousands of years in an agrarian society but maladaptive in modern society that requires 8 hr shifts worked 5 days a week for 50 weeks a year instead of simply 2000 hours when needed over the course of a year.

        • In other words, our society forces us to adapt to circumstances that we are not adapted to genetically. Reminds me of the book ‘A Hunter in a Farmer’s World,’ by Thomm Hartmann, which critiques how we blame and devalue kids with so-called ‘ADHD’ characteristics for not fitting into a world they were not designed to fit.

          Notwithstanding this important point, genetics are still the part we can’t change. Why not work on helping people figure out how to adapt better, or even work on creating a more flexible society where we appreciate and value differences and create niches where everyone can find a place to fit? Open classrooms for ‘ADHD’ sufferers is one very good example. The idea that all kids must ‘learn’ in a standard classroom and that those who don’t are ‘ill’ is simply nonsense. We force them to attend classrooms that are specifically designed to frustrate and defeat them and are surprised when they end up feeling frustrated and defeated?

          Genetics may help explain certain problems raised by modern society, but it doesn’t do much to help us solve them, except by perhaps reminding us that rigidity of expectations is bound to reduce the quality of life for all of us in the long run.

    • The book on “critical psychiatry” just announced by Gøtzsche also emphasizes the weakness of twin studies in assessing heritability.

      I see the whole idea that mental illnesses could be inherited as a guaranteed dead end.

      But I would like to see a review assessing the severity of the psychotic event compared to the severity of the triggering events, as that seems to be the only reason inheritability was brought into the discussion in the first place. There also may be a pattern of “infection” in some mental conditions, but I have not seen much data on that, either.

      Neither of these phenomena, assuming they actually exist, require the conclusion that some mental illnesses might have a genetic component. It does suggest another possibility, obvious to me: That some conditions may have a past-life component.

      This possibility becomes even more appealing if one rejects the biological models of mental illness, which seems to be what we are in the process of doing. For me, past life recall research confirms that the mind (and its emotional responses and past traumas) move with the being, not with the body. So for me, past lives must play an important role in human experience and patterns of human response.

        • If this is true, then the main question before us is how very young organisms learn to react in ways we consider “psychotic” when “bad things” happen to them.

          You realize that I am informed by a healing modality that is reported to be effective but that has not been tested by academics. These techniques are based on the observation that past life events (trauma, one could say) have an impact on this life responses to various stimuli.

          The only other explanation for responses that seem to be “learned” in very young organisms is that they were inherited. That means behaviors must be inheritable, and thus, supposedly, encoded in the genetics. I don’t see a lot of discussion here about the feasibility of this hypothesis. But it frankly seems to me like it would be unworkable.

          However, if we hypothesize a non-biological “mind” that can be inherited, then we get a mechanism that can explain much more complex and individualized behaviors appearing in organisms at quite a young age. If such a mind exists (and I can assure you that it does), then it must be addressed by any healing modality aimed at the psyche.

  3. Roll up! roll up! Grab someone’s miserable schizophrenia diagnosis, debunk its genetic heritability, call it a label, redesign that serious diagnosis by calling it just psychosis, then say everyone can have psychosis, especially anyone with a difficult life experience, and then tell everyone to get angry at those who are reputed to cause the psychosis, which means telling everyone to get furious at, here is a list…
    …a billion moms and dads, …university professors,
    …this government,
    …that government,
    …witches,
    …eccentric intellectuals,
    …free thinking radicals,
    …book readers,
    indeed get mad as hell at anyone who causes upset enough to spark the newly perceived definition of psychosis.

    It is no longer that your mom told you off for some row it is now that she caused your “psychosis”. Is this going back to the myth of refrigerator parents…that humans have the superpower to “cause” psychosis in each other…and so we all better tread on egg shells least we say the wrong words…the trauma causing…now psychosis causing words? We better buy ear plugs incase wrong words from wrong logic causes us to lose our mind…oh wait…if we lose our mind that might be freeing…that way we can be forgiven for being just a bit on edge and snarly…

    Really, I could go on but I am not supposed to have looked at the latest, since I am retired from MIA, flown the nest in my natty vintage aeroplane. But really, one can take any research paper and muddy the data, so I am not going to believe this article for one minute. I am schizophrenic and it is genetic and my grandmother had schizophrenia. It is an illness so severe that very rapidly your only way of surviving a week of constant hallucinations that are deeply traumatizing in themselves is to minimize the fact you feel traumatized by such trauma as is coming from the illness. This will have some effect on how the researchers measure whether someone feels traumatized or not. A schizophrenic may be profoundly traumatized BY THE HALLUCINATIONS and sit with a smile on their face. They have no choice. Not if they want to get through month ten or year two or three or four of unending relentless moment by moment torment. To miss that part out in these assessments is a problem.

    I like the SCHEMA study into schizophrenia, for bringing in a bit of BALANCE.

    Climate change is much worse than people realize and by the time they do humans may think the worst BUT the far future will be good. It is worth staying for that. Trust me.

    • And anyway what is the darned difference? If you say schizophrenia is a “label” and is not real when it has everything and more that psychosis has then how can you say psychosis which is almost identical is not a “label” and is real? I mean what you want to ascribe realness to is within schizophrenia and I would say the term “psycho” got movies made of it based on that “label”, so if the idea is to dim stigma from occuring why not go the whole way and say that there is no such thing as psychosis and there is only trauma and “it” causes remarkable symptoms?

      What bothers me is that a new myth will build up around schizophrenic people that says they are living in denial of trauma. This level of preaching against supposed denial is no different from old psychiatry’s coercion that put it that patients were in denial of their madness. The lecture on denial is the shadow side of conversion therapy.

      But don’t rush to reply, I should not have blurted out my appraisal. I am away to be an enchantress soothsayer.

      • Psychosis is a definable phenomenon. It can be seen, felt, observed, verified by discussion.

        Schizophrenia is a concept, and idea, that idea being that people who experience a very real psychotic phenomenon are ‘ill’ with a specific ‘disease’ or ‘disorder’ which is caused by a purported ‘chemical imbalance’ that can’t be seen or measured in any way and is now being denied by psychiatrists they ever claimed was true. Clearly, something is happening when a person is experiencing psychosis, and no one can rationally deny that. But for medical doctors to claim that they know this phenomenon is caused by a ‘disease state’ in the brain is reaching far beyond what any kind of scientific or observable data can tell us. It also gives power to the psychiatric system to claim the need to force ‘treatment’ on those who don’t want it or have observed already that it doesn’t help them or makes their situation worse.

        So in my view, anyone claiming psychotic experiences don’t exist is full of crap. But it does not follow that those experiences are definable as ‘schizophrenia’ as described in the DSM, nor that they are caused by faulty brain chemistry, nor that drug ‘treatments’ will automatically help the person experiencing psychosis.

        Again, I’d go to the mat to protect YOUR right to call the phenomenon whatever it is you believe best explains it. I do NOT support the idea that someone else can tell YOU that something is wrong with you called ‘schizophrenia’ until and unless they can objectively define this condition in ways that can be validated and verified objectively.

        Perhaps an easier analogy is the term ‘ADHD.’ Do kids act in the ways described as ‘ADHD’ in the real world? Of course, they do. It is a very common set of behaviors, especially in boys. Does the fact that they wrote down descriptions in the DSM and voted on how many ‘criteria’ are needed for a ‘diagnosis’ mean there is anything at all ‘wrong’ with kids who happen to fit that description? Absolutely not. It doesn’t even mean that kids who act that way have anything in common at all – they may each act that way for totally different reasons, and assuming that just because they act that way means they are ‘mentally ill’ is ridiculous.

        Same holds true in my mind for ‘psychosis.’ There may be one or ten or a hundred reasons why this phenomenon occurs. Maybe SOME such people really DO have a chemical or structural problem in their brains – but we don’t know if they do or which ones do. They may in fact be reacting to stress, but assuming ALL are that way because of stress is, as you correctly observe, not close to a valid inference. There may be thyroid problems, brain tumors, head injuries, huge anxiety, nutritional deficiencies – who knows? Because all they have done is collect a bunch of thoughts/emotions/behaviors that tend to occur together, described the behaviors and claimed it is an ‘illness.’

        So no, saying that the DSM-invented description of ‘schizophrenia’ is not an illness does NOT mean someone is saying that people who have psychotic symptoms are making it up or should just get over it or are all victims of trauma or any such thing. It is simply saying that there is no scientific proof that all or most people fitting that description can be claimed to have something specific in common that is ‘wrong’ with them that can be measured, identified, and ‘treated’ by a doctor.

        • What if psychosis was on a spectrum dependent on the severity of the trauma? There is growing evidence showing psychosis may be the immune systems defense against contradictory beliefs as in cognitive dissonance (this is often highly visible in politics and religion). Past trauma causes the immune system to over react to future stresses resulting in damage from stress hormones. One theory is that the stress hormones cause physical damage to the brain related to the damage of prescription psych drugs and the result is psychosis.
          I may to totally wrong but my bigger point is that there is value exploring theories bridge that darkness between objective science and the subjective theories that brought us to MIA.

          • I agree with your general premise. But what if psychosis isn’t caused by one thing? What if different episodes of psychosis are caused sometimes by emotional stress, sometimes by reactions to other drugs, sometimes by Lyme Disease or syphilis, sometimes by nutritional deficiencies, sometimes by opening oneself up to a higher level of spiritual awareness? What if there is more than one ‘spectrum’ involved? What if the idea that finding THE cause of psychosis is like trying to find one cause for ‘pain?’

  4. Psychiatrists are like physicists who deny the theory of relativity.

    Most mental illness can probably be traced back to the immune systems fight or flight response and the cascade of events triggered. The real illness is the variability in how an individual responds to stress. A malnourished sleep deprived body will react differently than a healthy body. Even a healthy body can be overwhelmed if the stress is either extreme in severity or in cumulative exposure. Ultimately the psychosis is a symptom of damage done to the ‘lizard brain’ from prolonged exposure to the adrenaline, epinephrine, and cortisol etc (precursors to IL’s and cytokines) released during the stressful event. This is consistent with the inflammation theory and explains SSRI’s are better understood as anti-inflammatory agents and not antidepressants.

  5. Joshua, Please forgive me but life is absurd, so basically all subjects are patently absurd. Being human is an absurd idea, also. As opposed to almost all other creatures, primates not included, because they walk on both all fours and just the twos, we are the only species that walks on just our legs and feet. So, in the scheme of the planet, we humans are the absurd ones. I do think those who state that our society is basically inharmonious with our human nature are on the right track. I, actually, think it is more so for some than others. Some people seem much more able to adapt to society as it is. Perhaps, that is now why we are beginning to include whether one is neurotypical or neurodivergent in our conversations. However, many who are in the study and advocacy of neurodivergence, do include some “categories” of mental illness, but consider them “acquired neurodivergence” almost like brain damage from say a car accident. However, the Autism spectrum, most learning and developmental disabilities, and even ADHD are not considered “acquired” neurodivergence. But this is an evolving field and these concepts may eventually replace traditional psychiatry, etc. which of course would cause some in psychiatry to might be somewhat nervous or anxious. Thank you.

    • rebel,

      We should not be promoting ideas like Mental Health or Neurodivergence because they serve no purpose, they are just ways that the powerful exercise their power over others.

      The OP’s article was still being written from within this eugenic paradigm.

      Joshua

      • Where, then, would you draw the line, Joshua? Promoting health DOES serve a purpose: The continuation of the species.

        Are you OK with screaming incoherently at a bus stop? Are you OK with stealing things just for fun? Are you OK with killing people just for fun? These are all signs of “unhealth.” Do you really consider the opposition to (or wich to change) such behaviors as a form of eugenics?

        • Mental Health is not Health.

          We have laws regulating most things. Disorderly Conduct is usually the lowest level of misdemeanor.

          Most drugs are illegal, except the ones a doctor prescribes for you.

          Now true, when the number of people violating becomes too high, the laws become unenforceable.

          If we start incarcerating people for the crimes they might commit, then all hope for our society is lost.

          Generally people will conduct themselves in a reasonable manner if they feel that they have some stake in the society. And that means that there has to be redress for previous severe abuses.

          In the vast majority of situations, people in the mental health system have been tracked into it by the family.

          We need protection from family scapegoating, and we need legal redress.

          We the law to protect people like the daughter of Sacramento Mayor Darrell Steinberg who was tracked into the mental health system at the age of 13. And today, she still believes she has a bad brain.

          We need the law to protect people like the aunt of CA State Senator Susan Eggman, because she was tracked into the mental health system. And since, Eggman has built her adult life out of targeting family scape goats, either with mental health, or with euthanasia.

          We need the law to protect people like Matthew Warren, who was tracked into the mental health system and then shot himself in the head at age 27.
          https://www.youtube.com/watch?v=HCUbog65dP4

          Now criminal codes are not always enforceable in every situation. They are practical things, not abstract philosophical principles. But I draw the line when there is evidence that someone has violated an enforceable criminal code.

          And as far as eugenics, the idea that someone has an innate defect, an innate genetic defect, and so their liberty should be revoked is of course an extreme form of eugenics.

          Joshua

          • Actually very FEW drugs are illegal if you simply consider them a chemical that interacts with the body. The supplement industry is largely regulated by consumer fraud laws that prevent companies from making false claims about a drugs benefits. This is why the criminal guilty pleas by the drug companies were for making false claims about the benefits and deceiving customers about side effects.
            I strongly agree with you on the problem of family making decisions for loved ones in the mental health system, especially for minors. Even in the best circumstances family is forced to make an unfair decision under pressure from psychiatrists and rarely with accurate information. It is important to recognize the family of the patients are just as much a victim of the fraud as the patients themselves. This same dynamic is occurring in elderly patients suffering from Alzheimers and just like with mental health we are seeing drugs based on fraudulent research that don’t work being given to individuals unable to give consent.

          • LivingPast, most recreational drugs are illegal, the chemical substances themselves are prohibited, so possession, use, manufacture, or sale, carry criminal penalties.

            Health supplements as you say are regulated by consumer fraud laws. But if they are found to be getting used as recreational mood alterants, they will probably be outlawed.

            Usually the idea that someone is “mentally ill” has started within the family. And this is so even when someone is not seeing doctors until they are an adult.

            The family of the patient are perpetrators, not hapless victims.

            And yes, the same sort of thing is going on with drugs in later life, and with CA State Senator Susan Eggman’s euthanasia law with the 15 day waiting period and requirement for outside witnesses removed.

            Joshua

  6. To simply read that someone takes the trouble to take down the whole myth that “schizophrenia” is some terrible genetic condition, that there’s something as terrifyingly wrong with you as faulty genes or a brain that’s not working, and have it, with clear science pointed out that it comes from trauma, stress and bullying, anyone that has had to deal with such a “diagnosis,” gets information they need to hear in order to be able to relate to themselves further, would they want to understand for themselves who they are.

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