Wednesday, July 15, 2009

Neurology vs. Psychology

Wired has an article exploring the seemingly ill-formed question whether Body Integrity Identity Disorder is psychological or neurological in origin:
The disorder is the subject of a debate between psychiatrists and neuroscientists about whether the brain physiology causes the psychiatric condition or whether the causality runs in the other direction...

Columbia University psychiatrist Michael First helped pioneer the identification of the disorder and his latest research suggests it’s just a subset of a larger psychiatric condition in which people become fixated on being disabled. On the other hand, Paul McGeoch’s recent work... seems to explain the disorder as a purely neurological disease resulting from a malfunctioning right parietal lobule, which appears to maintain the mind’s body map. His lab used fMRI to determine that four self-reported BIID patients’ right parietal lobules didn’t light up when their unwanted limbs were touched. Normal people’s did.

"Oh, this is certainly a breakthrough. We were stunned by the results," David Brang, a graduate student who co-authored a paper on the study with McGeoch, said recently on the Australian television show on which Vickers told his amazing story. "It’s very clear that this is a neurological phenomenon when it always been thought of as a psychological issue."

I wonder what he means? Are psychological and neurological explanations supposed to be competing, mutually exclusive explanations? Psychological events are grounded in brain events, after all, so why don't these fMRI studies simply indicate how the psychological disorder is realized in the brain?
[Dr. First] is, however, not yet convinced that a deficit in the right parietal lobe causes BIID. It's also possible that a strong desire to amputate a limb could transform neural circuitry in a brain region responsible for body image, he says. "There's a chicken-and-egg problem here."

Or is it more of a chicken and atoms-arranged-chickenwise (or "forest and trees") problem? Perhaps we could pin down a point of substantive disagreement if we focused on a single 'level' of explanation, say the neural level, throughout. Perhaps the point is that the neurologists are claiming that the disorder has a simple neural manifestation, whereas the psychiatrists think that the neural manifestation will be much more complex (effectively claiming that deficits in the "brain region responsible for body image" were caused by prior neural events that are best integrated and understood if we 'zoom out' to the level of psychology).

Simply put: if your mind is not how it ought to be, then neither is your brain, since the one gives rise to the other. So every psychological disorder is, in some broad sense, also a neurological disorder. But we can still draw important distinctions here. In particular, a disorder may be apparent as such at the level of the brain, i.e. in a way that's recognizable when looking at it "as" a brain, using purely neurological vocabulary. Or the problem may instead reside in more complicated neural patterns that are better captured using psychological vocabulary. There's a real question which of these two levels of explanation better captures and unifies the relevant phenomena.

So we can understand 'psychology vs. neurology' debates substantively if they concern this question of what level of abstraction unifies the disorder. Are the causes of BIID alike in respect of their superficial neurological form, or must we pull back to the level of psychology before their commonality comes into view? In effect, we may then call 'neurological' the problems that have a relatively simple neural manifestation, and reserve the competing term 'psychological' for disorders that are more unified at the higher level of abstraction offered by psychology.

Does that sound right?


  1. The only way I can even make sense of the question is on the lines you suggest. That being the case the question is simply which treatments are more effective, a purely empirical question. Frankly the whole thing strikes me more as grant protection than an actual problem.

  2. It seems that the most charitable interpretation of 'psychology vs neurology' debates like this one is in fact about the nature of the cause, though not in the ill-formed sense that realised properties 'cause' their realisers or vice versa. But there is good sense to the notion that a disorder might have merely neurological causes, meaning that it is the result of a breakdown in neurological mechanisms, say as a result of a stroke. On the other hand, a disorder might have psychological causes, such as intense, abnormal psychological pressures (e.g. strong desires, cognitive dissonance, complications from abuse) which of course have neurological realisations. One might imagine that in the former cases successful neurological intervention, were it possible, would be sufficient to relieve the disorder, whereas in the latter cases the disorder would relapse consistently if the social/psychological causes were not addressed.

    That being said, it is not clear to me that either of the investigators discussed in the Wired article have this conception of 'psychology vs neurology' in mind.

  3. Yes, it seems like you have it right.

  4. Hi Richard,

    This sounds right to me, except the idea that a psychological disorder is also (even in a broad sense) a brain disorder.

    Consider a software/hardware analogy: certainly a problem with a program is not always a problem with the hardware. It may make sense to speak of the phenomenon in question as a problem only at a certain level, and determining such a level dictates the kinds of interventions that could be effective.

    The analogy doesn't work perfectly, because the idea of a computer (i.e. the hardware) functioning perfectly well even though the software is buggy is much clearer than that of a brain functioning perfectly well (whatever that means) while the cognitive processes running on it are not. And the analogy totally fails if the relationship between the psychological and neural levels is simpler than that between computer hardware and software.

  5. I wonder if perhaps the idea is that we have two distinct sets of treatments for problems which have not yet been unified; and one of these treatments, which tries to fix the behavior (broadly considered) by adjusting brain chemistry, has received the label 'neurological treatments' and the other, which tries to adjust the brain chemistry by fixing the behavior, 'psychological treatments'. Thus the question would be whether a particular set of problems would be better treated by the sort of thing you get in one set of treatments or in the other. In that sense the distinction would be a purely practical distinction, about the best way to causally interact with someone to correct the disorder, rather than theoretical. (And the 'causes' in the first sentence would be a manipulability-theory sense of the term.)

  6. Kallan wrote: "Frankly the whole thing strikes me more as grant protection than an actual problem."

    The issue of BIID is indeed an actual problem, which affect me and many others in a real and significant way. It is not about grants at all.

    The question of psychology vs neurology is definitely an interesting and tricky one. As it relates to BIID, there seems to be a need to see the question as an "either/or", rather than points on a wide spectrum. The problem is that most surgeons and medical practitioners (in fact society at large) tend to view "psychological issues" as being resolvable through psychotherapy or pharmacotherapy. BIID has shown to be "untouchable" with those approaches. So if it is determined to be a psychological problem, it is unlikely that medical practitioners would help in the only way that helps. On the other hand, if is is seen as a neurological condition, it seems that doctor's reticence at providing surgery is much weaker.

    Personally, I tend to see this issue as being on a spectrum. Can't have one without the other, a bit like the yin/yang. From a purely philsophical point of view, that's where I stand. From a practical point of view, I'll take anything that will get us closer to surgery being accepted as a viable option for people who have BIID.

  7. I think "psychology" means only a non scientific reason for the problem. So it would be no illness or a subject for scientific work. If there is no neurologic cause psychology can find a fictional reason but in this reason less people are interested because it would be art schiences or fictional thinking.

  8. * It would seem odd for people to assume that psychological problems are always resolvable. (And even odder to think that they have "non-scientific" causes, whatever that means.) Even on a purely pragmatic/political level, it might be better to fight against such societal ignorance, rather than trying to warp our categorizations to get people to respond in the ways we want them to. (Certainly in the long run...)

    * Brandon's treatment-based distinction is an important one, though it seems potentially misleading in this context. At least to my ear, calling a phenomenon "neurological" or "psychological" seems to be suggesting something about its nature, not about how to treat it. It could be that some psychological problems are best treated via paradigmatically neurological means (and vice versa), and of course some might not be treatable at all (at least given current knowledge).

  9. The issue raised in the post seems to turn on a basic point about the nature of causal explanation. It’s a perfectly sensible scientific question for climate scientists to ask whether global warming is caused by natural geo-biological forces or by human industrial activities. Yet, from a certain perspective human industrial activities simply are natural geo-biological forces. Similarly, scientists can debate whether an ocean rock formation is produced biologically (say by coral) or by an non-living chemical reaction. Yet, from a certain perspective all of biology is reducible to chemistry. The point is that even if some form of reductionism is true about mental states, this doesn’t imply that scientists can’t perfectly well ask whether the best causal explanation employs psychological terminology rather than strictly neurological terminology.

    More importantly, however, focusing on debate about the causal explanation of BIID obscures the moral debate about the treatment BIID. The discussion here seems to presuppose that the question of how to treat BIID is simply a matter of determining which treatments are most effective at reliving distress. However, as with transgenderism, there is an extra moral issue involved in BIID, which is whether to change the mind/brain to fit the external physiology or to change the external physiology to fit the mind/brain. This question cannot be answered on the basis of causal efficacy alone. In my paper on this subject, I’ve argued that the answer to this question turns on whether it can be rational for the patient to regard the desires involved in BIID as a part of her identity: Craimer, (2009). "The Relevance of Identity in Responding to BIID and the Misuse of Causal Explanation," American Journal of Bioethics 9(1): 53-55.

  10. Mikio has it right. And this is not equivalent to asking what level of abstraction unifies the disorder. It is possible both that the root causes are psychological and that both levels of abstraction unify the disorder; i.e. there could be a single neurological expression.

  11. Paul - if the neurological description is just as simple and unified as the psychological description, then what justifies privileging the latter level of description as providing "the root cause"? (Or do you merely mean to highlight the possibility that the neurological expression of the disorder, but not of its cause, be simple and unified? In that case we wouldn't disagree.)


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