Twin Separation Studies: pro and con for biological basis of psychiatric disorders

jock_suitI have to apologise, I’ve been busy with other things these two months, like making a living and building a house – in the mud. All good clean fun but this will have to be a bit shorter than usual.

A question from sunny California:

“My name is Alex and I am a PhD candidate at UC Berkeley in California. I wonder if you could answer a question about your thought-provoking 2011 paper

Cells, Circuits, and Syndromes

… What do you think about evidence from identical twin separation studies (e.g., showing the heritability of autism/schizophrenia) and examples of individuals who exhibit sharp personality changes immediately following traumatic brain injuries? Isn’t this evidence that mental disorders are the result of low-level biological abnormalities, at least in some cases?”(The reference is:

Cells, circuits and syndromes. A critique of the NIMH RDoC project. Ethical Human Psychology and Psychiatry13: 229-236. An expanded and much less polite version is available as Chap. 11 in my book from 2012, The Mind-Body Problem Explained: The Biocognitive Model for Psychiatry. Ann Arbor, MI: Future Psychiatry Press).

There are several complex questions buried in this missive but first, in that paper, I don’t address the question of causation of mental disorder. All I say is that whatever NIMH think they’re doing with their concept of neural circuits, they won’t be addressing it, either. In fact, I’ve since found a statement from our good friend, Dr Thomas Insel, Director of NIMH and chief protagonist of the neural circuits/ Research Domain Criteria project (coming to you at stupefying cost) where he wrecks his own project for all time. He actually says what I have been claiming all along, that their project is not designed to understand the level of the brain at which mental disorder is generated. In a talk on TED from earlier this year, he specifically says we know that the form of the brain’s critical capabilities is not amenable to physiological analysis. Despite this, he is proposing to commit psychiatric research to basic neurophysiology for decades to come. This is not encouraging.

Let’s leave that for the time being and focus on the other important questions in Alex’s enquiry.

The question of how it is that people with brain damage show personality changes is, to me, self-evident:

IF the brain is a high-powered switching device (which it is) subserving the rapid, real-time manipulation of information (which it does) derived from a variety of sources (elementary neurophysiology) AND that information is important in determining how people behave (which I accept as true), THEN IT FOLLOWS that any physical agent that disturbs the brain’s switching functions (chemicals, infections, metabolic disorders, concussion, brain damage etc) will interfere with the observable behaviour.

If the change is temporary, like getting drunk, then the person will come back to normal tomorrow. If it is permanent, as in brain damage, then he will remain different as a result of the damage. If the damage involves frontal regions, then the highest cerebral functions will be involved, meaning judgement, discretion, subtlety etc. Unless somebody wanted to claim that human behaviour is unrelated to brain function, then I don’t see there is much room for dispute in this position.

HOWEVER, that’s not what psychiatry is about. Psychiatry isn’t about brain damage. I know orthodox psychiatry trumpets the “chemical imbalance” mantra but all my work says that (a) they have never defined what this could mean, and (b) I have argued that it is meaningless, anyway (which may go some way toward explaining why people like Dr Insel avoid the question). The crucial issue is this: Is it true that all mental disorder is necessarily due to an organic disturbance of brain function, or is there room for “something else”? I say there is room for something else, but the something else is not, as Daniel Dennett and Company assume, necessarily magic in nature. By invoking information processing as the “something else,” we escape the reductionist dead end of biological psychiatry and also sidestep the slippery problem of substance dualism, or what Dennett dismisses as green slime in the head. That is, there is a third way, a rational way, between boring biology and fanciful spirits. I don’t ever say there are no spirits, we just can’t deal with them in our present knowledge system.

So to move on: Can we explain mental disorder in terms of what people know and believe and hope? Yes, in principle, we can. It’s not difficult at all, it’s what is called the cognitive approach, which says that whatever people believe determines how they act and think and feel. Pretty simple. Now for the difficult question: Can we explain serious mental disorders in just these terms, or do we have to invoke biology to do that? I don’t believe we do. Firstly, there is absolutely no convincing evidence to suggest that there is a consistent biochemical, genetic or any other lesion in any significant mental disorder (I don’t count as mental disorders things like Lesch-Nyhan Syndrome, an exceedingly rare genetic defect that causes mental retardation). Second, an information processing model of mental disorder is available which can account for the phenomena of major mental disorders.

Third, what weight do we put on that vexed concept of heritability? Let me give you an example. To our shame, Australia now has the third or fourth highest incidence of obesity in the world (60%+ of males are overweight or obese) but don’t get too worried about it. We are told by the Health Dept. that the heritability of obesity is high so clearly, it isn’t just a matter of our heroic Aussies being a bit piggish. But what does heritability tell us? I say it says nothing. Heritability is a crude measure of the genetic contribution to the differences between individuals; it says nothing about the genetic causation of a condition in an individual. Let’s go back to 1945; the incidence of obesity in this country was zero, and overweight was exceedingly rare. Even when I went to school, there was never more than one overweight child per year (ie one in about 130 skinny kids; looking at the photos, fat wasn’t fat by modern standards, and the rest of us were very skinny). However, it gets worse: “At the current rate, it is predicted that 65 per cent of young Australians will be overweight or obese by 2020” (Victorian Health Dept).

What does this say? It says that in 1945, the heritability of obesity was zero (ie no variance) but now it is said to be much higher, as in this review: “Numerous studies show that child weight status is highly genetically influenced. In a sample of 66 pairs of 3- to 17-year-old twins residing in the New York metropolitan area, the heritability of BMI and percent body fat was estimated to be 86% and 76%, respectively.” As for the heritability of major mental disorders, it is still a fact that the vast majority of people who acquire a diagnosis of schizophrenia do not have a first or second order blood relative with the diagnosis. Something else is going on.

I say the “something else” resides in the individual’s “total informational state,” meaning what he believes about himself, the world and his place in it. Trouble is, that informational state is not a matter of biology, it’s a matter of information. And information, as Norbert Wiener said 65 years ago, is not material: “The mechanical brain does not secrete thought ‘as the liver does bile,’ as the earlier materialists claimed, nor does it put it out in the form of energy, as the muscle puts out its activity. Information is information, not matter or energy. No materialism which does not admit this can survive at the present day.” (WienerN (1948, Rev. Ed. 1965). Cybernetics, or Control and Communication in the Animal and the Machine. Cambridge, MA: MIT Press. P132).

If we postulate that the major mental disorders are a matter of self-sustaining disturbances in the individual’s informational state, in a perfectly healthy brain, then we can account for them without invoking unproveable biological disorders. So where does that leave the genetics of mental disorder? I’ve mentioned Jay Joseph before: he says the genetics of mental disorder aren’t where the biological psychiatrists think they are (LINK TO HIS PUBLICATIONS AND MANY FREE TEXT LINKS). See the highlighted articles section for a quick rundown of some of his major points.

Einstein is reputed to have said that madness is doing the same thing over and over again but expecting a different result. Maybe this chap qualifies. On July 9th, Melbourne’s Herald Tribune reported on a man in Shepparton who died in a house fire at his neighbour’s house the night before: “He was staying there because his other two homes had burned down from his habit of smoking in bed. The 52-year-old’s bungalow caught fire in February, then his house on the same property burnt down on June 30. His next-door neighbour, a middle-aged woman, offered to take him in while he looked for new accommodation, but her home also caught fire around 1am today.” So now you know: going to bed is a health hazard.

Some months ago, I mentioned a psychiatrist in France who was convicted of manslaughter when her patient murdered his relative. Across the Atlantic, the Supreme Court of New York thought making people share responsibility for crimes was not a good idea. When the trustee winding up the affairs of the convicted swindler, Bernard Madoff ($65billion type swindler, they don’t muck around in Manhattan), tried to sue the big banks that had underwritten his crimes, he was told he couldn’t do it. The trustee argued that they had known, or ought to have known (ie they had the information and could work out what it meant if they could add up) that Madoff was a crook but the court found a loophole for the banks to wriggle through. Phew, that was close. Imagine being held responsible for driving the getaway car for somebody who had just robbed a bank.

A tragic suicide note by a young veteran of the Iraq was is causing some people to rethink their stance. Daniel Somers died a few months ago after years of mental pain. On level after level, he was failed by people who should not have failed, by a system that should not have failed. This commentary on his eloquent statement says more than enough.

People who start wars often don’t think about the effects their actions have on others. The mental effects of overwhelming psychological distress were not recognised for most of the twentieth century. In particular, armies and the psychiatric profession bitterly resisted the notion that ordinary men could be driven over the edge by routine military experiences. “Must have been a weak character,” was their standard response, “send him away, no pension for weak characters.”

In 1982, I saw an elderly man who has served on the Western Front during the First World War. He was a second lieutenant in the AIF at a time when subalterns had an average life span of three weeks after arriving in the trenches. That’s Average: for every one who lasted five weeks, there was one who was dead within the week. When I saw him, he was deeply ashamed of lodging a claim for mental disorder as he understood it meant weak character but his wife had recently died and he could no longer manage alone. I took the standard history and found that he met every requirement for a war-caused mental disorder, one that would now be called PTSD.

While he was there, I looked through his file which dated back to the day he enlisted in 1915. He had first applied for treatment rights in 1920 but was rejected on the basis that officers didn’t suffer mental disorders and he was clearly a malingerer. He tried again in 1930 and met the same reaction so he did nothing further until 1941, when he applied to re-enlist in the Army Reserve. He was told he was mentally ill and was not suitable but it was deemed not due to military service. He tried one more time in about 1952 before he finally got the message that real men don’t break down in war.

He was an engineering student when he enlisted, so he was made an officer and went to France with his unit, comprised of men from his own town. He knew them all, many of their fathers worked for his father, who owned a sizeable business, and he had played football with them before he went to university. His unit was second over the top in the first major action involving Australian troops on the Western Front, on July 19th, 1916, at a village called Fromelles. This was to be a feint to relieve German pressure on the British armies in the disastrous Battle of the Somme. At 9.00am that day, after a heavy barrage, he watched as the first unit scrambled over the parapet and lined up, laughing and joking as they got ready to march across No Man’s Land to the wrecked German trenches. Unfortunately, the Germans weren’t reading the same script and had survived the barrage, along with their heavy machine guns. As this twenty year old junior officer watched in horror, the first wave of troops was mown down. He had a few minutes to ponder this before it was his turn to order his friends up to their deaths. At 9.05am, he blew his whistle and his home town friends joined the 5,500 Australians killed that morning, all for no purpose whatsover. He was injured but his mental injury devastated him and he was discharged later that year.

At the age of eighty-six, he didn’t want treatment. All he wanted was somebody to write in his file that he was not a malingerer, which meant that he could go to the War Veterans’ Home. I was pleased to do that and thought nothing more of it until two years later when his daughter rang to say he had died, peacefully, and respected. “Knowing that you believed he was not a liar made all the difference,” she said. This is the point about being mentally injured by wars, it lasts such a long time.

I wonder who will treat the Iraqis and the Afghans for their PTSD?

A note on the recent survey in Bob Whitaker’s Mad in America blog. That paper is attracting some interest. Good. So far, I’ve heard nothing from our friends in NIMH. Must be an oversight on their behalf.

his has nothing to do with anything except having a good time and not doing any damage or hurting anything.

Highlighted Books and Articles

This month a colleague of mine, Christopher Struble MD, a psychiatrist in the US will be highlighting Jay Joseph’s research.

He will be providing a brief synopsis of the major points from two of Jay Joseph’s papers, “Twin Studies in Psychiatry and Psychology: Science or Pseudoscience (2002 FULL TEXT),” and “The Fruitless Search for Genes in Psychiatry and Psychology (2013 FULL TEXT)” which is chapter 8 in a new book “Genetic Explanation: Sense and Nonsense (2013).” Of note this book was edited by Sheldon Krimsky, from Tufts University, best known for his 2003 book, “Science in the Private Interest.”

First off, Jay Joseph’s entire list of publications can be found on his website and many of these have links to full text. I’ll be summarizing in the form of a list and all data comes from the two papers above. I’ll do my best to be clear and summarize as succinctly as possible.

1) It has been widely acknowledged by high profile genetics proponents that the family studies (looking at distribution of mental illness in families) are confounded by environmental factors. As Ming Tsuang put it, family studies can only provide “the initial hint that a disorder might have a genetic component.”

2) The classical twin method compares reared together identical twins to reared together fraternal twins. The major flaw in these studies is the assumption that the environmental conditions of monozygotic (MZ) and dizygotic (DZ) twins are roughly the same. He has numerous references which show that MZ are treated more similarly by their parents and social environment, spend more time together, and share a closer emotional bond than DZ. He quotes Sandra Scarr, a twin method proponent, “the evidence of greater environmental similarity for MZ than DZ twins is overwhelming.” He references a 1967 schizophrenia twin study by Kringlen which showed that over 90% of MZ experience “identity confusion” during childhood (only 10% for DZ), 72% of MZ were “brought up as a unit” vs 19% of DZ, and 65% of MZ had an “extremely strong” level of closeness vs only 19% for DZ. Jay Joseph also mentions that “I’ve never seen these results discussed by any twin researcher other than Kringlen.”

3) The assumption mentioned above was classically called the “equal environmental assumption” or EEA for short. Due to the lack of evidence for it, twin researchers modified EEA to become the “equal trait-relevant environmental assumption.” Essentially, this new assumption acknowledges the original EEA as being wrong but “claims that the question is really about whether MZ experience more similar environments as they are etiologically relevant to the trait in question.” This was taken up by Bouchard, Kendler, and other leading twin researchers. This means that it needs to be proven that something in the environment that is more similar between MZ than DZ is associated with the outcome and thus the previous research was still legitimate. This then places the burden of proof on twin method critics and Bouchard himself has stated that this is a “very difficult task.”

4) Joseph mentions other factors compromising the validity of the twin method, most notably lack of adequate and consistent definition of the trait under study and non-blind diagnoses.

5) Later there was a shift to studies of twins reared apart in order to resolve some methodological difficulties which on the surface would seem to mitigate the problems listed above. However, “due to small samples, there have been no systematic reared-apart twin studies for any psychiatric condition.” To boot, one of the major studies, the Minnesota twin study by Bouchard did not allow access to their data.

6) These “reared apart” twins do not properly mitigate the similar environments problem primarily because of the selection bias inflicted by the simple fact that they needed to know about the other twin in order to respond to the study. This meant that most twins grew up in similar socioeconomic and cultural environments (often in different branches of the same family), often lived in the same home for many years AND had frequent contact. He states that “most pairs had significant contact with each other for many years.”

7) Joseph posits that “the only valid study would compare the similarity of MZ twins reared apart from birth and unknown to each other to a control group of biologically unrelated pairs of same-sex age-like strangers who are matched on all other post-natal environmental variables shared by reared-apart identical twins.”

8) “Buried within the twin research literature on schizophrenia is a finding that the pooled concordance rate for same-sex DZ twin pairs is two to three times greater than that of opposite-sex DZ pairs (11.3% vs 4.7%). Because the genetic relationship of same-sex and opposite-sex DZ twin pairs is the same, and because schizophrenia rates among males and females are roughly equal, from the genetic standpoint we should find no significant difference between these pooled rates. Therefore, these findings are consistent with non-genetic explanations of the causes of schizophrenia, since pairs who share the same degree of genetic relatedness, but who experience more similar environments and a closer emotional bond, are consistently more concordant for schizophrenia than are pairs who experience less similar environments and weaker emotional bonds.”

9) In his 2013 book chapter he provides a segment from the study which had largest proportion of the rare cases in which MZ pairs were reared apart from early life and grew up without knowing that they had a twin sibling. The first bit of this paragraph reads “In all 12 pairs there were marked intra-pair differences in that part of the personality governing immediate psychological interaction and ordinary human intercourse…..the twins behaved, on the whole, very differently…..”

Joseph provides a quote from the Nobel Prize-winning chemist Wilhelm Ostwald from the early twentieth century, “Among scientific articles there are to be found not a few wherein the logic and mathematics are faultless but which are for all that worthless, because the assumptions and hypotheses upon which the faultless logic and mathematics rest do not correspond to actuality.”

In summary, remember that concordance is the percentage of the time that when one MZ or DZ twin has the disorder the co-twin also has the disorder. The mathematics make the major assumption that the difference in concordance rates between MZ and DZ groups are strictly attributable to genetic factors. This assumption is made because MZ and DZ twins are falsely assumed to have equivalent contributions of environmental factors because they’re raised in the same household. However, the data above shows conclusively that this assumption is false and thus minimizes the amount of trust we can place in the entire body of twin research as “proof” of the genetic basis of psychiatric disorders.

Send your questions to with the word ‘question’ in the title. Start submitting now for next month.

Thanks again to Alex who provided the question for this month’s newsletter.
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One Comment

  1. “So to move on: Can we explain mental disorder in terms of what people know and believe and hope? Yes, in principle, we can. It’s not difficult at all, it’s what is called the cognitive approach, which says that whatever people believe determines how they act and think and feel. ” Aaah now this is the $1000 question isn’t it? ‘Cos cognitive therapy works with a model of consciousness in which beliefs are as much determined by behavioural habits as behaviour is conditioned by beliefs. Much in the way that Sartres concept of ‘bad faith’ amounts to a declaration that humans – as the irrational creatures they are, – are quite capable of believing something they don’t in fact believe. So the ‘simple’ linear cause-effect explanation of mental disorder as behaviour conditioned by beliefs is inadequate. Theres a feedback loop and we have to insist that mental disorder must be mental and not behavioural. (because of course then we should theoretically be able to ‘cure’ mental illness just by changing behaviour. This is of course exactly what drugs do and we know that drugs don’t cure mental illness, they only render it more manageable – both for patient and therapist.) Your PTSD examples demonstrate admirably that all human beings basically are existentially vulnerable but some just seem to be born hypervulnerable. Obviously the anti genetic faction will argue “No, something in their early experience makes them hypervulnerable.” In much the same way as the theory of genetic vulnerability, this has not been scientifically proved, nor has it been disproved. So I’m still banking on the old stress-vulnerability model which proposes the existence of a disposition to an abnormal stress vulnerability which however only develops into mental illness if it is activated by some adverse environmental cue.

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