What causes mental illness?

There’s a long and dishonourable tradition of blaming the mentally ill for their own illness.  For a long time, people thought the mentally ill were possessed by evil spirits or demons.  Here, for example, is the description of a man who was ‘exorcised’ by Jesus:

And when he [Jesus] was come out of the ship, immediately there met him out of the tombs a man with an unclean spirit, who had his dwelling among the tombs; and no man could bind him […]: neither could any man tame him.  And always, night and day, he was in the mountains, and in the tombs, crying, and cutting himself with stones. [Mark 5: 2-5]

Clearly, the bible authors were not in the habit of using standardised criteria to classify the people they claimed Jesus had encountered, but it certainly seems likely that anyone displaying these characteristics today would be described as mentally ill.  (Well, either that, or as an emo kid.  I mean, look at the evidence – the guy spends all his time on his own, crying and self-harming, and lives in a graveyard.  I bet if they’d gone to his dwelling among the tombs they’d have found about a million pairs of skin-tight black jeans, and enough eyeliner to sink the Titanic…)

Jesus, as was his wont, has a bit of a natter with the supernatural phenomenon:

And he [Jesus] asked him [the emo kid possessed man] ’What is thy name?’  And he answered, saying, ‘My name is Legion: for we are many.’  [Mark 5: 9]

Again, the diagnostic categorisation is absent, but a modern-day person asked the question ‘What is your name?’ who replied by saying he was called ‘Legion, because we are many’ would be likely to be described either as mentally ill, or as a fan of supernatural horror films.

Anyway, really the key thing is what happens to this ‘mentally ill’ man.  He manages to overcome his demons long enough to worship Jesus [Mark 5: 6], who casts out the demons and causes them to enter a herd of swine, who immediately take a running jump off a nearby cliff and drown.  After this, the man is, ‘miraculously’, cured:

and see him that was possessed with the devil, and had the legion, sitting, and clothed, and in his right mind  [Mark 5: 15]

Interpreting this myth is easy: those of us who are mentally ill need only worship Jesus and we will be cured.  It follows from this that everyone who is mentally ill has either deliberately turned their back on god, or, if they are a practising christian, are insufficiently sincere in their faith.

This is one of the main ways that mentally ill people have been and are blamed for their own illnesses.  In fact, the frequency with which we use the phrase ‘overcome his demons’ shows just how central this myth still is to our explanations of mental ill-health.  But there’s also a rather newer way in which the mentally ill are blamed for their own illness, and it’s done, shockingly enough, by people who claim to be in the business of supporting the mentally ill, and even curing them.  I’m talking, of course, about the psychological model of mental illness.

Broadly speaking, there are three main theories of the cause of mental illness.  The first of these I’m going to call the medical model, as it proceeds on the assumption that mental illness is identical to physical illness, except that the physiological disruptions take place in the brain, rather than in other areas of the body, and consequently have mental symptoms.  The second theory I’m going to call the psychological model, as it holds that mental illness is wholly different to most physical illness, and results from a combination of negative life events and poor ‘coping skills’.  The third theory is an uneasy synthesis of the two preceding theories, and holds that a combination of medical and psychological factors cause mental illness.  It’s difficult to be precise in this definition, because it seems to mean different things to different people.  So, some people argue that ‘serious’ mental illnesses (like Bipolar Disorder or Schizophrenia) are caused by medical factors, but the rest are caused by psychological factors, while some others argue that there is a biological ‘predisposition’ towards mental illness, but it is ‘triggered’ by negative life experiences.

I should make sure that I come right off the fence here and state flat-out that I am very far from being impartial in this ‘discussion’.  I think, so far as genuine, enduring mental illness is concerned, the psychological model is nonsense, and psychologists little better than quacks.  I am convinced that, within 100 years at the most, there will be no such job title as ‘Clinical Psychologist’.  I think there will be psychiatrists, but psychiatry will be a radically reformed specialism, and will tend to be seen as a branch of neurology – the only difference between a neurologist and a psychiatrist will be that the former will focus on surgery, while the latter will make use of medication.  I also think there will be counsellors, but these will be limited to helping with sub-clinical problems (someone who is finding it difficult to cope with grief, for example), and to helping the mentally ill manage their symptoms.  Counsellors will not seek to claim, as many psychologists currently do, that they are able to divine the cause of mental illness, or to cure it.

This position is, of course, a belief, although I do also think that the balance of probabilities supports it.  Statistical analysis is making a genetic cause for certain mental illnesses (like Bipolar Disorder) seem very, very likely.  Research into conditions like Alzheimer’s is also demonstrating that physiological conditions within the brain can cause disruptions in the mind that are very, very similar to those that are associated with mental illnesses, and can be treated with the same drugs – The Shrink, for example, has discussed the benefits he has achieved treating dementia patients with antipsychotic medication.  Nonetheless, my belief remains a belief, and I wouldn’t want to claim that it was anything more than that.

For me, the greatest stumbling block encountered by the psychological model is that it struggles to explain why some people who experience negative life events are mentally ill and others are not.  Take a hypothetical example of a family of children growing up in difficult economic and personal circumstances with a parent who is mentally ill.  This is a scenario that many who subscribe to the psychological model believe would lead to a greatly enhanced risk of the children themselves becoming mentally ill.  Now imagine that one of these hypothetical children grows up to suffer from mental illness while the remainder stay healthy.  (This is a not uncommon scenario.)  A medical model that takes account of genetic factors can very easily account for why this is – because of the random selection of genetic material at conception, only one child has inherited the genetic factors necessary to cause the illness.  The psychological model, on the other hand, encounters difficulties – what marks out as different the child who goes on to develop the illness?

This is something that cuts close to the bone for me.  I have three siblings, and I am the only one with serious mental health problems.  If we are to believe in the psychological model, this is something that it has to satisfactorily account for.  Why was I unique in responding to the upbringing I shared with my siblings in this way?  If this is not the result of  physical factors that apply only to me, then what does it result from?  It seems to me that the psychological model is going to struggle to explain this in terms that don’t end up blaming the victim (i.e. me) for a personal weakness, or an inability to cope.

There is a history of mental illness in our family, although, as with many families, it’s not spoken about in those terms.  My grandmother would experience lengthy bouts of unspecified illness, during which she would take to her bed.  These illnesses were always described as ‘a virus’, and were of sufficient concern that my granddad would take days at a time off work to look after her.  It was during one of these bouts of illness that my grandmother died, on the day that my granddad had returned to work after a period of two weeks looking after her.  The family version of events is that she had become confused, and died of an accidental overdose.  It’s not, I think, a huge leap to reach the conclusion that her unspecified illness was recurrent severe depression, and her death suicide.

So, how can we explain the fact that my grandmother was mentally ill, that her illness skipped a generation altogether, and then manifested itself only in one of her four grandchildren?  The answer, of course, is that all of this can be very easily explained if we assume a genetic cause.

It’s perhaps unlikely that a single defective gene is responsible for depression – if it was, it would probably have been at least tentatively identified already.  If depression does have a genetic cause, it’s much more likely to be the result of the interaction between several genes.  For the sake of clarity, however, I’m going to label the combination of genetic factors that leads to depression as though it were a single gene.  I’ll be calling this gene a (that is, a lower case letter ‘a’), and I’ve labelled the opposite combination of genetic factors – the one that leads to an absence of depression – gene A (that is, an upper case letter ‘A’).

In almost all cases, an adult human possesses two versions of every gene, one that they have inherited from their mother, and one that they have inherited from their father.  It is also frequently the case that one version of a gene takes precedence over the other, if both versions are present.  The gene that takes precedence is called ‘dominant’ while the other is known as ‘recessive’.  In this case, I am presuming (because fewer people are depressed than are not depressed) that the version of the gene that leads to no depression – gene A – takes precedence over the version of the gene that leads to depression – gene a.  In other words, gene a is recessive, while gene A is dominant.

There are four ways these versions of the gene can be combined in a person, but these four combinations lead to only three possible outcomes.

  • The first possible combination is AA, in which a person has inherited a dominant version of the gene from their father, and another dominant version from their mother.  This combination leads to a person who is not depressed.
  • The second possible combination is Aa, in which a person has inherited a dominant version of the gene from their father, and a recessive version of the gene from their mother.  Because the dominant version takes precedence over the recessive version, this person is not depressed; however, they are a carrier of the ‘depression gene’, and may pass it on to their children.
  • The third possible combination is aA, in which a person has inherited a recessive version of the gene from their father, and a dominant version of the gene from their mother.  Again, the dominant version takes precedence over the recessive version, and so the outcome is the same as with the second combination – a non-depressed carrier of the depression gene.
  • The fourth possible combination is aa, in which a person has inherited a recessive version of the gene from their father, and another recessive version from their mother.  This combination leads to a person who is depressed.

If depression has a genetic cause, then my grandmother must have been a double recessive – that is to say she must have had the genetic makeup aa.  My father, who did not suffer from depression, must have been a non-depressed carrier, as his mother (my grandmother) only had recessive versions of the gene to pass on.  In other words, he must have had the genetic makeup Aa – a dominant gene from his father and a recessive one from his mother.  If my mother was also a non-depressed carrier (Aa or aA) then it would be possible for my mum and dad’s children to have the full range of possible genetic combinations – AA, Aa, aA, and aa.  This coincides exactly with the situation that exists with me and my siblings – the three of them do not suffer from depression, while I do.

This is, of course, no more than informed guesswork.  Depression may not have a genetic cause, in the same way that not all illnesses with physical symptoms have a genetic cause, and even if depression is caused by a genetic abnormality, there’s no guarantee that it works as neatly as in my example above.  In fact, if it’s multi-factoral (i.e. more than one gene is involved) then it’s almost certainly a lot more complicated.

The fact remains, however, that a medical model like this is able to provide an elegantly simple account of why I suffer from depression, but my three siblings do not.  It is also able to explain how the depression skipped a generation, and how I ‘caught’ it from a grandmother I never knew – she died 8 years before I was born.  The psychological model, on the other hand, isn’t able to provide an answer to any of these questions, except to fall back on the unsubstantiated assertion that there is some deficiency within my character or personality that explains my illness.  It’s for this reason that I’m inclined to believe – until compelling evidence to the contrary comes along – that major depression, in common with all other mental illnesses, has a physical cause.

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9 Responses to What causes mental illness?

  1. npal says:

    So, you mean to tell me you can actually rule out every and all possible interferences (genes aside) that differentiate you from your siblings, effectively assuming that for all environmental purposes, unbringing, experience and perceived experience, you and your siblings are one and the same, so in that sense it should have been either all or nothing?

    Since personality and mood disorders have become pretty much a plague with anxiety disorders and depression taking the major portion, does that mean that there’s this common gene going around that somehow has eluded discovery as the main or major cause for depression? The research on schizophrenia, which is thought to be heavily influenced by genetic factors hasn’t pointed beyond the shadow of a doubt to one or more genes responsible for it. Now I have little doubt that as far as schizophrenia and its derivatives are concerned, research will eventually point out exactly what’s the genetic factor. Do note however that the onset is never exactly the same, so even if there IS a strong genetic base, researchers will need to take more things into account, possibly other genes influencing the onset and prognosis of the disease.

    Depression though is far too complicated to be reduced to a mere genetic flaw. Certainly there might be genetic factors that make you more positively predisposed to mood disorders but to deny the environmental/social contribution in favor of genes seems as much nonsense as acquiting the knife because your body is made in such a way as to be susceptible to wounds.

    Also, the Clinical Psychologist belief is moot. If everyone could learn and do everything, we’d have just GPs doing all the work. Deviation in science means one can focus on one thing, do it well, and expect the other experts to do their job just as well. The psychologist exists to claim those cases that can either be helped by some sort of psychotherapy in combination with psychiatric medication or whose illness is such as to avoid medication entirely, and no, psychiatrists don’t work like that, at least not in the hospitals I’ve worked. Another fact regarding medication is that, as you may know, medication cocktail efficiency as far as depression is concerned yields mixed results. I’ve known more than enough patients that weren’t responding to medication well, even with a series of different prescriptions, and a few in particular had what appears to be a random recovery.

    As far as brain research on mental illness goes, the best I’ve seen is symptom description and the assumption that neurotransmitter density and movement is somehow related to a mental illness. Well, if it were that simple, how come anti-depressants don’t really work that way for all patients? And how come electrospasmotherapy sessions can actually work in some cases of severe depression that doesn’t seem to respond to medication?

    Do note that even if medication did work without fail as in most physical illnesses, the difference is that your organism will never make antibodies for mental illnesses. You will eventually NEED some form of therapy to practice the behaviors that will shield you from being re-exposed to the same illness. Remember that I’m talking about mood disorders and a number of personality disorders. Illnesses like of the schizo- kind seem to always need medication. Also remember that psychiatric medicine is potent, like many other medicine and should not be taken lightly, so forcefeeding it to patients for years unending isn’t even what most practicioners themselves want.

    Lastly, if you wanted to acquit yourself of the blame people place on you because many have this retarded belief that somehow the mental patient is responsible for his illness, you didn’t need to go as far as to outright deny the psychological contribution. It’s no one’s fault in the end, and I’m not sure whether it’s the patient’s responsibility to get out of it, but that’s entirely another subject.

    If we knew everything about how we work, there’d be no “medical councils”. Opinions in what’s supposed to be hard science is really pathetic, but people choose to avert their eyes from that fact.

    PS For good or ill, strong belief in some higher power does seem to help a number of both physical and psychological illnesses… if we actually don’t count that I’ve seen more than enough patients with psychotic elements claiming they’re messengers of god :P

  2. I do not think interpreting that part of the Bible is as simple as you make it out to be. Especially if you take other parts into account.

    For instance at church today the focus was on the man who was cured of his blindness, who had been blind from birth. The Pharisees asked Jesus if he was blind because of his own sin or because of the sin of his parents, to which Jesus responded that he was not blind for either but in order for God’s glory to shine through him (which it did after Jesus cured the blind man).

    Now this does beg the question, wait God makes people suffer so that He can demonstrate His glory through them? What? That doesn’t sound very nice.

    However, God does not make people suffer, sin is the cause of suffering, but sometimes He does not prevent it for His own providential reasons.

    In the case of mental illness, and indeed demons, well, demons do not only attack the weak, or those who have invited them in. The people who are closest to God are themselves far more likely to be attacked by demons than ordinary people, since the demons want to prevent their sanctification. And it only takes a little sin – and who among mankind is not prone to slip up – for them to gain power over people.

    I do not think therefore it is fair to assume that any particular person suffering from demonic attack is to blame for it, or to judge them as somehow particularly weak or devoid of God to be in that way.

    Not that I am equating demons and mental illness necessarily, but it is true that a non-religious person would have no choice but to assume demonic attack was some kind of mental (or bodily) illness.

  3. NiroZ says:

    Not your best article. Not only did you work in a straw man attack (nobody I know holds that psychological view, including psychologists), you made a false dichotomy (genes must be it, because upbringing can’t be it) and you made a reverse post hoc ergo propter hoc fallacy (other people had the same upbringing as me, therefore it can’t be the causation). Not to mention over simplify everything.

    The real most popular psychological theory on depression is the cognitive theory of depression. http://encarta.msn.com/encyclopedia_761578989_3/Depression_(psychology).html (5th entry on google, if you’d bothered doing actual research before making a straw man)
    That is, a combination of personality traits (that may or may not be genetic) and circumstances. Circumstances that can be changed. That’s what CBT is all about. I thought you said you figured out CBT in 10 minutes.

    Just because it wasn’t the upbringing doesn’t mean it wasn’t the environment. It could be the peers you interacted with, the adults in your life, it could be an event that you experienced, it could be something that happened in your school grade. It could be something that happened after you left home. It could be something you ate (like that neuroparasite that lives in cat feces), it could be a disease you suffered that got to your brain. You haven’t ruled out any of these possibilities, but you jumped straight to genetics.

  4. Alex says:

    Cutting himself with stones? Good heavens, that’s not very practical. I do rather like the idea of a biblical emo kid, though.
    Honestly, I don’t know about mental illness having a genetic basis. I think there are almost certainly multiple factors at play with something this complicated, and there being a psychological basis for mental illness is by no means reflective of any kind of blame on the sufferer.
    Oh, and tempting though it may be to pin mental illness on demonic possession, I find it hard to believe in a supernatural phenomenon that can occasionally be beaten into submission by taking pills. But then, I find it hard to believe in supernatural phenomena of any kind.

  5. jono says:

    Great post Athelread,

    I think the psychological model is just a load of victim blaming bull.

    NiroZ – I read your link, apart from being a very oversimplified statement of the psychosocial model, it also fails yet again to distinguish correlation from causation.

    I’d like some objective proof that the thinking styles referred to in the post are causal factors in triggering depression and not simply correlational

    I’d also like proof (and i mean in both cases scientifc evidence) that the thinking styles thus referred to are causal not symptomatic.

    As far as i’m concerned the psychological model of depression has got a lot of work to do, before it can be shown to be anything other than hotair.


  6. aethelreadtheunread says:

    Thanks for the comments, and for taking the trouble to engage with what i say in such detail.

    npal & NiroZ – you make a lot of points, and i want the opportunity to discuss them in greater detail. For this reason, i’m planning on responding to you both in a new post that will appear in due course. For now – thanks for your comments. :o)

    Sophia Marsden – we clearly come at the matter of demonic posession and so forth from rather different angles. I do not accept as true those things for which there is no evidence, which means that, until such time as evidence emerges, i reject all supernatural phenomena, including ‘god’, ‘the devil’, ‘demons’, ‘sin’, and so forth. I’m afraid i stand by my interpretation of the myth i discuss, too – your attempts to re-interpret it seem to me to be wholly ineffective. But thank you for commenting. :o)

    Alex – i guess it depends on whether he sharpened the stones first, or not… ;o) I’m afraid i must respectfully disagree with you regarding psychological explanations of mental illness – they cannot work unless they assume some difference between the character and behaviour of the mentally ill and the mentally well. And, since one pattern of behaviour leads (allegedly) to mental wellness and the other to mental illness, it follows that one is ‘good’ and the other ‘bad’. It doesn’t matter if no-one is actually sitting there rubbing our noses in the blame – the theory is still based upon a concept of blame.

    I should perhaps add that i think that plenty of the therapy done in the name of psychology can be very helpful in learning to manage mental illness. (This is the sort of thing i think can be helpfully done by counselors.) :o)

    jono – thank you for the compliments. :o) In return, i am very much inclined to agree with everything you say.

  7. Well, I have bipolar disorder. So does my dad. So does my dad’s first cousin and my 2nd cousin. I think that says “genetic” don’t you?

  8. Pingback: What causes mental illness: a follow-up post « Aethelread the Unread

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