The Corpus Callosum

About 15 years ago, I was giving a lecture on psychiatric medication to a group of MSW students.  One student asked a question that was intended to be provocative.  She asked, "how can you justify giving medication to treat a problem that is obviously psychological in origin, like posttraumatic stress disorder?"

What she was referring to, was a paradigm that was commonly held at the time.  Specifically, there was this notion that some problems were psychological, and others were biological, in origin.  It was thought, by some, that there was a clear distinction between the two kinds of problems.  

A corollary to that was the notion that psychotherapy was the correct treatment for psychological problems, and some kind of biological treatment -- medication, for example -- was the correct treatment for biological problems.

As an aside, I personally don't use the word "justification" to describe anything in the practice of medicine.  

Rather, I think in terms of "rationale."  There is only one possible rationale for the routine use of any medical intervention; it has nothing to do with speculations about the origin of the problem being treated.  The rationale is that the treatment has been tested, and has been found to work.

Anyway, back to the main point.  About one year ago, I was leading a seminar with some Ph.D. students in clinical psychology.  In the course of discussing something else, I mentioned, for historical context, the idea that people had thought at one point that there was a clear distinction between biological and psychological problems.  A student chimed in: "But nobody really believes that any more, do they?"

Hmmm.  I am sure some people do.  What is more, it is a paradigm that might be useful for them.  As they say, "all models are false; some are useful."  Personally, I have found it to be useful only in a very limited sense.  

Sigmund Freud was said to have been an amateur archaeologists, and some have thought that his hobby was related to the development of one of his central theories.  He thought that the best way to solve problems was to uncover their origins.  I think that does work, sometimes.  Often it does not.  Often, there are simpler, less time-consuming methods of approaching the problem, even within the realm of psychotherapy.  Although the origin of a problem might suggest a particular solution, it certainly does not tell you a priori what potential solution is most likely to work.  

A good example of the lack of a clear distinction between psychological and biological processes is found in a recent presentation on the effects of childbirth.  Childbirth is obviously a biological process for women.  The psychological and anatomical changes are rather obvious.  It is much less obvious, however, that there are biological changes that accompany fatherhood.  Therefore, it might be tempting to think of fatherhood as a time of psychological transition, rather that a time of biological change.  

However, this is not something that one can discern merely by thinking about it.  You have to do the study to learn the truth of the matter.  And when you study the neurophysiology of new fathers, you do find that there are changes.

Is it really surprising that a person's physiology changes in response to one's social environment?  

If the physiology changes, would it then be reasonable to think that anatomy might change as well?

Fifteen years ago, it was thought commonly that the structure of the brain did not change, once adulthood was attained, except for degenerative changes caused by disease, or aging.  This is now understood to be a misconception.

The study I referred to previously is described here.  (HT: Minding the Planet)

Fatherhood boosts male brains
25 July 2006
New Scientist

FATHERHOOD could be good for your brain, at least if you're a monkey.

It's already known that male primates, including men, experience dramatic hormone changes when they become fathers. Yevgenia Kozorovitskiy and her colleagues from Princeton University realised that certain parts of the brain contain receptors for these hormones. So they studied the brain structure of common marmosets (Callithrix jacchus) that had become fathers. The species is rare among mammals in that fathers share in caring for their offspring.

In both first-time and experienced fathers with dependent offspring, the team found structural changes in the prefrontal cortex, a region of the brain important for planning and memory. In these areas the neurons showed signs of enhancement, with a greater number of connections. They also had more receptor sites for the hormone vasopressin...

Vasopressin is an interesting compound; it serves multiple functions in the body, and it is not obvious why that one compound does so many different things.  It is one factor that controls the salt-water balance; it contributes to regulation of blood sugar levels; it affects clotting; and it has various effects in the brain.  (See Bora, Carl, and PZ for details on the role of vasopressin in circadian rhythms and in pair bonding.)

I could get into a discussion of the supposed behavioral effects of vasopressin, but my sense of the state of knowledge, at this point, is that scientists do not really understand it well enough to say anything with much authority.

As Carl and PZ pointed out, these things are never simple.  Attempts to relate one neurotransmitter with one behavior usually turn out to be fallacious. Even so, it is clear that there is a biological basis to behavior.

Does that mean that behavior is biologically-driven, and that psychology has nothing to do with it?  Of course not. It would be more accurate to say that biology and psychology are two different models; each model can be used to explain behavior; and in some cases, one model is more useful than the other.