Thursday, July 10, 2008

biology vs psychology: false dichotomy?

I was speaking with a very intelligent and insightful patient today who mentioned that he'd felt his problems (depression, some obsessional traits, a mild eating disorder) were all 'psychological' until he found a drug that significantly improved them. From that point on he was convinced they were 'biological,' and embarked upon a quest for the Magic Pill that would solve all his neuroses at a single swallow.

I see references to this sort of split all the time, and not just from patients but also from highly educated physicians and scientists. Somehow they consider that our behavior* arises from two distinct sources: one composed of neurons, synapses, and neurotransmitters, and another composed of experiences, drives, and willpower.

If you buy the biological theory of behavior at all, then it makes little sense to imagine a dividing line between 'biological' and 'non-biological' causes of behavior. Experience alters neurochemistry just as surely as medications do.

Here's a nice (but somewhat technical) piece of work discussing some of the cellular-level changes that have been observed to be triggered by real-world experience (Takahashi, Svoboda and Malinow).

Evidence abounds for the utility of 'talk therapy' in psychiatry. In order to separate the 'biological' from the 'psychological,' one would have to believe that there exists an entirely separate underpinning of human behavior that operates on some ethereal plane, unrelated to the biomechanical world of synapses and neurotransmitters.

If you're going to accept that neurobiology underlies behavior, then there is no clear point at all where you can divide the biological from the psychological. If you accept that experience exerts its effects through alteration of our neuronal activity, and you accept that hearing your therapist is an experience, then there is no room for some nebulous 'non-biological' effect. Your therapist's words tickle your ear neurons, which tickle your brain neurons, which make subtle changes - sticking themselves to some of their neighbor cells, unsticking themselves from other neighbors, changing the rate at which they spit neurotransmitters at each other - and voila! You change your behavior.

That the line between biological and psychological is fuzzy to the point of nonexistence is indeed starting to permeate the general consciousness, at least to a degree. This usually arises in discussions of ethics, where the whole edifice of crime-and-punishment rests on an assumption of free will. This assumption is being radically challenged by evidence that our behavior is heavily determined by factors not under our direct control (genetics and medication in particular).

This opens up another can of worms, because we frequently associate 'biological' with 'beyond our control' and 'psychological' with 'within our control.'  Hence my patient (and many like him) and his Magic Pill search.

But I think the educated world at large is not yet ready to join Steven Pinker in declaring us will-less playthings of our genes and environment. Fine for now, but I'm curious to see what we'll make of coming scientific advances that will no doubt push us even closer to the will-free wall.

*I'm using "behavior" intentionally to encompass all of the workings of the human brain that are manifest to others. I'm doing this very deliberately because the question of whether mind is biological at all is a very sticky wicket and not something I can afford to get into in this limited space.

Wednesday, July 2, 2008

free will and eating disorders

We've a number of eating-disordered patients on the unit at the moment.  Eating disorders have never been a particular interest of mine; yet as I work more closely with eating-disordered patients, I've come to realize their problems raise a number of interesting philosophical questions.

We've all had the experience of being of two minds.  We want something, yet we do not want it. One experiences this on a regular basis, yet it rarely disturbs the view of oneself as a single, integrated ego, a unified mind.  However, the problem is very severe in the eating-disordered.

How to want to be well but also not want to eat?  How to want one's life back, to know that the eating disorder has wrecked it, to understand that one flirts with death, yet be so petrified of food?  Even my patient Ms. G., weighing just 35 kilos and desperate to regain a normal life, was yet utterly unable to prevent herself from binging, vomiting, and binging again.  "Obviously I have free will," she wailed unprompted, "but somehow I can't stop doing it."

Our medical student was surprised at her intelligence, unable to credit her self-destructive behavior because "but she's so smart!"  But 'smart' has nothing at all to do with it; in fact, quite the opposite: anorexics may have higher than average IQs.

(This may be tied to the well-documented association between anorexia and the need for control.  Besides body weight, academic achievement is another area where due diligence generally yields the desired results, and thus appeals to the controlling anorexic personality.  In fact, Dura et al. note that 'perfectionistic striving' actually yields better academic results for anorexics than would be predicted by their IQs alone.)
This makes a degree of sense when one considers that a certain level of complexity is required in order to deny one's own basic drives so severely.  At the most straightforward level of functioning, one merely obeys one's basic drives - hunger, thirst, fear, desire - pursuing the most immediate means of gratification.  At a somewhat more sophisticated level, one may delay instant gratification for a bigger payoff later on, forgoing one candy now for two candies later.  Ultimately, one may come to value successively loftier intangibles above the basics: staying up late to finish that big paper; starving for one's art; giving one's life for one's country.

Well then, how to be cognitively impaired, like our patient Ms. S., and yet have an eating disorder?  Ms. S. had been impaired since birth, and she behaved for all the world like a sweet and coquettish child, grinning impishly at the team, asking for hugs, requesting praise for her accomplishments.

At first I could not believe someone functioning at this simple level was sophisticated enough to have an eating disorder.  I thought she must have an organic illness, a food sensitivity or irritable bowel.  And yet as we weaned her down to the most elemental and gastroenterically benign food supplements it became clear that the problem was not in her bowel, but in her head.  She played all of the typical eating-disorder games: saving food, dumping food, vomiting food, mixing and freezing and thawing and refusing it, drinking gallons of black coffee and diet soda, and on and on and on.  

Ultimately it became clear that at least one of the reasons for Ms. S.' eating patterns had, unsurprisingly, to do with control - a common theme among eating disordered patients.  In Ms. S'. case, though, it was more to do with control over her family than over her body.  Still living with her mother in her forties, Ms. S. yearned to go out and build her own life.  She found that refusing to eat allowed her to exert a measure of control over her large, loving, yet stifling family, all of whom rallied round her and raised a ruckus of attention over her malnourished status.  Which was, evidently, far preferable for Ms. S. than sitting quietly on the couch watching TV all day and being ignored by those with lives of their own.

I hadn't given Ms. S. nearly enough credit for the complex, multilayered psyche she evidently possessed.  Humans are deep creatures, even the simplest of us.  

Not too much can go wrong with a simple machine like an abacus or a bacterium.  But as you add more bits and parts and cogs and circuits and cells and networks, the number of ways things can go wrong explodes.  Ultimately you end up with personal computers and human beings, both of which are endlessly surprising and infuriating in the sheer number of things that can go wrong with them.  Hence computer wizards, and psychiatrists.

chemical love

One of my more interesting recent patients had a problem straight out of a daytime talk show. This was a young gay man in love with his heterosexual roommate. The two of them had a very close relationship, eating dinner together, going to movies as a couple, and generally engaging in very couple-like domestic activities. They also had a surprisingly open relationship. The gay man had confessed his ardor to the roommate, and the roommate, while he did not return the sexual feelings, was mind-bogglingly relaxed about the whole issue and the two of them remained as close as before.

Matters took a turn for the worse when the roommate acquired a girlfriend. Naturally the gay man could not stand the girlfriend and resorted to drinking alone in his room or going for long drives whenever she was around. Ultimately he became so depressed and consumed by the situation that he was unable to work, could not sleep, lost interest in his hobbies, and finally sought psychiatric help.

At first nobody on the treatment team could understand the situation, and in particular the behavior of the roommate. We speculated that perhaps he was a closeted homosexual who unconsciously returned the feelings, or else that he simply couldn't bring himself to give up the incredibly cheap rent offered by his lovesick roommate (who owned the apartment).

The answer turned out to be a bit more complicated. I sat down with both men for a frank discussion of the situation, and found that, at least to casual observation, their relationship appeared as close and open as had been described to me by the gay patient. Together we dissected the timeline of their relationship. It turned out they had been ordinary good friends until they began to use the drug Ecstasy (MDMA). Over the course of a summer they had used the drug weekly together - rarely with anyone else - in the process cementing a bond that ultimately became more like a love relationship than anything else.

It is likely impossible to convey the emotional power of Ecstasy to anyone who has not tried the drug. Roughly, it works by reversing the direction of the reuptake transporter that vacuums leftover serotonin out of the synaptic cleft. This dumps enormous amounts of serotonin into the synaptic cleft - far more than would ever normally be present there at one time. Just as chocolate cake overstimulates the taste receptors that evolved to detect the more mild and nuanced sweetness of fruit, Ecstasy overstimulates circuits designed to underlie the natural pleasures of romantic attachment and sensory experience.

In a stark demonstration that love really is just chemistry, Ecstasy can make you feel a gush of deep affection for just about anyone sharing the experience with you. It's Cupid's Arrow in chemical form.

In this particular case, these two men overstimulated their 'love circuits' together over and over again for an entire summer. It's no wonder the gay one fell in love with his friend. As for the straight roommate, evidently Ecstasy can't alter sexuality (unsuprising, as anyone who's tried it will tell you Ecstasy has little to do with sexual feelings, and in fact often inhibits them). But it did seem to have triggered many of the other hallmarks of romantic love. The man gazed affectionately at his roommate, expressed all manner of deep and abiding emotion for him, was wracked with guilt for the suffering he'd caused. Everything was there but the sexual attraction.

The chemical basis for emotion is nothing new, and at this point carries little shock value. Yet it is still difficult to believe how easily we can manipulate our deepest emotions with a little diddle to the neuropharmacological machinery.

What was the cure for this young man? Fighting fire with fire, I prescribed him Prozac. Prozac works by paralyzing the same reuptake transporter that is reversed by Ecstasy. Instead of being vacuumed back out of the synaptic cleft when their job is done, the serotonin molecules loiter around in the cleft. The simple way to think about this is that more serotonin in the cleft equals more happiness, duh - though in fact the biological effects of SSRIs such as Prozac are somewhat more complicated than that (see Nutt et al for a useful summary).

As one might expect, then, Prozac blocks the effects of Ecstasy. With Prozac in your system paralyzing your reuptake transporters, a nice fat pill of E has no more effect than a sugar tab. That was one little-known side effect I thought might be useful in this particular patient's case.

A more well-documented side effect of SSRIs is inhibition of sexual function, including the ability to orgasm (see Rosen et al. for review). In addition to this, there are some anecdotal reports that SSRIs such as Prozac have adverse effects on romantic love. This is a much mushier and less well-documented realm. I found nothing about it on PubMed, though I did find a bit of schlock in Psychology Today that discusses the phenomenon. If this latter bit did turn out to be true, I would wonder whether the effect were secondary to inhibition of sexual desire or whether it involved a distinct group of neural circuits.

Based on anecdotal reports from people who have used them, it sounds as if SSRIs may in fact dull the capacity for deep emotion. You don't feel sad anymore, you even feel kind of happy, but the happiness is a sort of pleasant zoning out rather than a meaningful joy. Indeed, by some reports the entire spectrum of emotion is flattened out (see, for example, comments posted by readers on this WebMD blog).

Much has been made of the possibility that we are depriving ourselves of essential human experiences by medicating away our emotions (see, for example, this review of Eric Wilson's book Against Happiness). Of course, many others more articulate than I have also argued the opposite side of the story (see this other review of Peter Kramer's Against Depression).

As is often true, I find myself taking a position somewhere in the middle. I don't want my patient to be zoned out forever, but I can't help but think that he's already had more than enough character-building for a while. A little Prozac in this case is probably a good thing.