Friday, November 11, 2011

Evolutionary Psychiatry and Bipolar Disorder

A couple of papers came to my attention this week that relate to what I consider "real" evolutionary psychiatry.  That is, what are some evolutionary reasons we might have genes that make us vulnerable to psychiatric disorders.  The "real" evolutionary psychology academics consider this discussion to be "Abnormal Psychology,"  and like all evolutionary psychology, it is somewhat controversial.  I actually don't think about the disorders much as evolving in an evolutionary light… I tend to think in terms of the human body and gut and neurons working outside design specs, thus breaking down (that is "my" version of evolutionary psychiatry).  But the overlap between one ev psych and another deserves some scrutiny, because certainly I can make the case (and often do, to patients, particularly those with bipolar and ADHD and OCD) that there are elements of these disorders that are quite adaptive to certain situations, as long as the maladaptive parts don't derail everything.

Part of my major hypothesis is that the industrial/digital age and processed, low-nutrient food has brought out more severe and different phenotypes of underlying vulnerabilities, and has also brought out seemingly new illnesses ("atypical depression").  Thus a less destructive phenotype (a mildly paranoid schizotypal person, for example, who will be more creative than the average person, as compared to full-blown schizophrenia, which impairs functioning to a terrible extent) will persist in the population due to selective advantage for certain traits.

My only previous article on "real" evolutionary psychiatry can be found here: The Creative Advantage.

Well.  It is fitting the first of the two papers today comes from Medical Hypothesis.  Melissa McEwen sent it to me - I think she likes that journal because it is crazy and it makes her laugh.  (Here is advice for those aspiring to be published there:  The purpose of Medical Hypotheses is to publish interesting theoretical papers. The journal will consider radical, speculative and non-mainstream scientific ideas provided they are coherently expressed.) 

I have no publications, myself, though I have assisted in some research efforts.  My mentor would like me to cobble something together from all the research I've done for the blog on affective disorders, or something.  I never did fancy myself much of an academic… thus never felt the motivation to write anything boring enough to be published in a journal ;-)… however, it would certainly add to my street cred.  I don't know that I can write the exotic papers for Medical Hypothesis, however (Melissa sent me a paper previously about some sort of reptile origin theory of illness?  I can't remember, but it was hysterical, and it must have slipped through part of the editorial process as it was also mostly incoherent).  Back to evolutionary psychiatry!

Evolutionary origin of bipolar disorder - revised (EOBD-R) is the paper in question, by one Julia A. Sherman of Madison, Wisconsin.  A quick google search brings up her original EOBD (sans R) from 2002.  And as much as I make light of Medical Hypothesis, I do have to admire the originality of the paper, noting that it is wildly speculative and the basic premise is most likely incorrect.

Ms. Sherman connects the dots between the circadian rhythm issues and vulnerability to bipolar disorder (manic episodes are known to peak in the spring time, when the light increases exponentially day by day in extremely northern or southern latitudes.)  In a nutshell, the EOBD suggests that bipolar disorder developed as an adaptive trait in the northern temperate zones which had more extreme winters during the ice age.  If you were hypomanic all spring and summer, you got a lot of stuff done, and then you could slow down and "hibernate" (be depressed) during the winter and not use much energy.  The "R" or revision in question actually brings in the interesting bit of Neanderthal DNA that all of us non-San Bushmen (or otherwise directly derived from Africa without side-stepping through Europe or Asia and coming up close and very personal with other hominids) seem to have.  Ms. Sherman thinks that bipolar disorder is a Neanderthal trait.

Hmmm.  She brings in the observations of a German psychiatrist from the early 20th century, E. Kretchmer, who noted that folks with bipolar disorder tended to be of a certain "pyknic" constitutional type.  They have a "thick trunk, relatively short limbs, and a big head on a short, thick neck."  Apparently, several other researchers in the early 20th century, when they were really into measuring heads and body sizes and making silly claims based on the measurements found that manic-depressive patients were more likely to be pyknic (endomorphs),  and schizophrenics were more likely to be "leptosomic" (ectomorphs).  A much newer study in 2003 also confirmed this finding. Sherman believes it is striking that Neanderthals are also described as having big bellies and short limbs.  Interesting.   In addition, people of African descent apparently have lower incidence of bipolar disorder in some studies Sherman cites.  However, there is no reliable data among truly purely African populations such as the San.

There is more to the paper, but I hit the highlights.  I'm not entirely sure what to think.  There is no question that bipolar disorder has a seasonal component and that light and dark therapies can be useful. Hypomania, with the extended bursts of drive, energy, and creativity can also be very adaptive.  And one can imagine being moderately depressed during a cold, dark winter might keep a small tribe of Neanderthal out of each other's hair, when there might have been nothing much to do anyway.  I think the pyknik bit is a little ridiculous - as we know, actually, both schizophrenia and bipolar disorder are related to metabolic syndrome, even in people who have never been on medicines.  I also would bet a poodle that there are San bushmen with some bipolar disorder out there, but symptoms might be attenuated by their latitude and hunter-gatherer lifestyle with plenty of socialization and exercise (though they do like those omega 6-filled mongongo nuts), according to my own wildly speculative theorizing…

The second paper is far less... imaginative and was published in the much more staid Journal of Affective Disorders.  Creativity and affective temperaments in non-clinical professional artists:  An empirical psychometric investigation.  These researchers looked at 152 undergraduates in art school (or other creative majors) vs. 152 undergraduates who were in majors predicted to lead to professions "mostly requiring the application of learned rules" (like accounting, I suspect).  The students were tested with several standard measures to detect subclinical and clinical manifestation of cyclothymia (a mild variation of bipolar disorder), and also other scales of general health and demographic data.  I don't think it will surprise anyone to know that the creative students were significantly more likely to score into the cyclothymic range on these scales.

An interesting quote from the paper:

Positive mood, and happiness in particular, was postulated to fuel creativity. Enhanced positive affect is a feature of both hypomania and mania, which are core symptoms of bipolar disorder and may predispose people within the manic-depression/bipolar disorder spectrum to creativity. By contrast, postulated that depression might provide fresh insights which can be executed into the artistic oeuvre during the energized phases of cyclothymia.

 So it appears that bipolar disorder is linked to creativity, which may have an adaptive advantage.  I don't think that is particularly controversial, but it is nice to see more studies on the subject.  Now were Neanderthals more creative than homo sapiens?  At least in the springtime?  That might help Julia Sherman's hypothesis!

Edited to add - a Neanderthal winter love song? By Primitive Radio Gods (right click to open in new tab).


  1. For what it's worth, it's noted in research that patients with severe psych illnesses show physical asymmetry, and shorter legs, consistent with intrauterine development atypicalities. This is why people covet beauty; beauty (symmetry/pleasing face) indicates healthy development.

    My paternal grandmother was schizophrenic; I have never met or observed her (she sorta died in the state ward before I was even born), however my father who is "normal" (although he is quite paranoid and severely anxious and has alchoholism) has very short legs with abnormally longer arms/wider shoulders, suggesting some kind of developmental atypicality. My father in older age has developed severe osteoarthritis of the hip and had a hip replacement , which perhaps is consistent with skeletal abnormalities. My father has always told me that he looks much more like his mother.

    To say this appearance is neanderthal is sort of silly; genetic + environmental issues affecting the intrauterine environment would probably be a better explanation as to why severely mentally ill patients often show asymmetries in faces and short limbs.

  2. I do think stuff like this is an example of good observation. Like the previous commenter, ItsTheWooo said there may be some good explanations for this. It think when we study illnesses/syndromes/disorders, we should leave no stone unturned, if we see a pattern or higher risk with a certain physical trait, that could lead us to something truly helpful.

  3. It is quite typical for Russian country folks from villages to be wide-shouldered,short, with short legs. It is a common believe that such body type is caused by not eating enough of meat and heavy physical labor at early age. Their descendants in cities are usually taller with longer legs.

  4. Oh and i think it's strange that they would argue traits for bipolar disorder would be neanderthal/hunter gatherer; I would assume this would have been selected for post agriculture. What would a hunter-gatherer do with a late march, early april mania? Run around day and night in the cold and snow, trying to hunt animals which are still lean and malnourished from winter? I would imagine a manic hunter-gatherer would just die early of dehydration and starvation, running about freaking out with no rewards for his efforts.

    It should be noted, mania is a risk when light first starts to increase - it is that INCREASE of light which triggers the circadian rhythm to speed up. This occurs well before animals and plants are available for a hunter gatherer to obtain (as the light is just beginning to return, the animals would still be lean from winter due to lack of plants due to lack of light).

    But you know what a farmer would do with a jolt of mania in early spring and late winter? Get up earlier, work longer, to plant crops and prepare fields, which later would reap rewards in later seasons.

    The value (if one could call it a value) of having cyclical mood disorder, with starts and stops of energy and motivation, is it allows you to do/think/imagine quite a lot, or very little. This is only useful if one has the opportunity for mastery over their environment where you can put your intensity to use. If you are a slave to nature (like a hunter-gatherer) there really isn't much benefit to having a mind like a cheetah (big jolt of energy, and then long down times).

    Cats evolved the ability for their bodies to pour out intense bursts of energy to catch prey at the right opportunity, which they pay for by sleeping all day and conserving energy when predation is not needed. Some humans evolved circadian rhythm atypicalities which make their minds do the same thing, except the trigger is not visible prey (as it is for a cat), the trigger is the first break of good weather after winter/reduction in sleep/melatonin. Time. Opportunity.

    In the agricultural society, which rewards planning and long hours and intense labor independent of natural opportunities, would select for traits where some people could conserve mental/physical energy when not needed, and draw from it when it WAS needed (the earliest crack of spring). Farming is all about time and timing. So is bipolar disorder. On the other hand, HG is all about present opportunity (e.g. observing a herd of animals), and HGs would not benefit from biological traits for their circadian rhythms to partition time and energy.

    I fail to see what the utility would be of this mental trait, if one is bound to the laws of nature and must wait for animals to fatten up again, wait for plant food to become available again. You would just be running about aimlessly looking for opportunities when it was still far too early in the season for them; you would be far more likely to die early by expending energy when the opportunity is not yet available to capitalize on it. Hunter gatherer bands are always limited in their nutrition, which is why they support so few people. Running around more is not going to increase their nutrient yeild; they peak out and overhunt everthing very easily.

    On the other hand, speeding up on break of light it is the perfect timing for an agriculturalist to get to work preparing and planting. The agriculturalist, who has mastered nature and controls food like god, is limited in nutrient production only by his energy and how rapidly he responds to seasonal opportunities; the more energy he can access during the preparation seasons, the more successful nutrient yeild he will reap later. He is limited only by his efforts during the right time.


  5. Draft Sequence of the Neanderthal Genome (2010)

    "Mutations in NRG3 have been associated with schizophrenia, a condition that has been suggested to affect human-specific cognitive traits (65, 66). Mutations in CADPS2 have been implicated in autism (67), as have mutations in AUTS2 (68). Autism is a developmental disorder of brain function in which social interactions, communication, activity, and interest patterns are affected, as well as cognitive aspects crucial for human sociality and culture (69). It may thus be that multiple genes involved in cognitive development were positively selected during the early history of modern humans."

  6. I think "atypical" is the key word and it is related to brain lateralization, not body type. My last blog post is about this very subject, which might interest you, Emily, and your readers: Cheers!

  7. Woo and Mrs. Ed - yes, I wouldn't have brought up the paper at all if it didn't have an interesting perspective… but I agree that bipolar disorder is more suited to agriculturalists than Neanderthals.

    Robert - I'm assuming you are not *the* Bob Dole - thanks for the links! There are a lot of similarities between schizophrenia and autism with respect to some of the genes and frontal areas affected, just at different brain development stages. However, Bipolar is a little different (though the genes overlap with schizophrenia too - and I do love to lump…)

    Dr. Platt - will definitely check it out. Over at "Free the Animal" Richard had a recent post about the Bicameral Mind - which I think is interesting but doesn't fit the neuroscience evidence. Have you read Previc's book about dopamine and evolution? That stuff is cool. I have several posts on lateralization and dopamine and evolution that are easier to find at Psych Today - oh, I'll link them…

  8. Thanks! I'll check yours out too. I have read a long article by Previc; he also came up in a previous blog of yours that I read and in Michael Winkelman's book on shamanism ( who also referred to my research). All in the same week, as if synchronicity does not exist. One caveat on Swedenborg, who Previc mentioned in his article as looking right when he had a vision to support his left-hemispheric thesis. Wulff in the Psychology of Religion says Swedenborg's lost his voices and visions after a stroke (he didn't mention which side it was on); but he didn't lose his speaking voice, suggesting his non-dominant hemisphere had been their source. If Swedenborg had atypical bilateral or right lateralization for language, this might explain his anomalous experiences, even his rightward gaze..

  9. The dopamine/schizophrenia link question (and brought over from your prior creativity post) makes me want to ask about your thoughts on available neurotransmitter level testing methods. I gather what's available is urine testing. This paleo gal here does a rather enthusiastic but not so scientific take-down of its accuracy:

    Do we have an accurate way to measure NT levels in people and do you think those tests actually tell us anything given all the other factors involved (serotonin in the gut, receptor sensitivity, numbers of neurons in various parts of the brain, etc)?


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