Wednesday, December 17, 2008

Neuroimaging Research

I think modern technology is wonderful.

We now have machines which can image the living brain and measure activity in different parts of the brain as events are happening.

Whenever there are interesting new measuring devices, there will be many research scientists who will compete for time on the machines, to conduct experiments.

In psychiatry, brain imaging has been an active area of research. Most every week there is something in newspaper headlines about brain imaging findings pertaining to human emotion, perception, personality, or behaviour.

I think such studies will eventually help guide us to understand and help a greater variety of problems, perhaps in a more proactive and specific way.

But, in my opinion, we are not nearly there yet. Functional imaging has few practical applications. And, in the excitement about seeing something light up on a computer screen, people are suspending common sense at times.

For example, the other day I was reading an article in the paper, which was citing an imaging study apparently showing that people had less empathy for those struggling with addiction, compared to those with other problems.

I would not doubt that many people truly do have less empathy for addicted indididuals. But in the article, the "proof" that people had less empathy was that some area of their brains, when scanned, showed less activity, when contemplating scenes depicting individuals with addiction problems. This imaging finding was used as a rhetorical device in the article.

This reminds me of trying to determine if people outside believe it is daytime or night-time, by making them wear hats that have solar panels on top, and measuring the intensity of light picked up by the solar panels during the day.
--i.e. such measurements are indirect, imperfectly correlated, and absurdly unnecessary--
People may certainly believe it is daytime when the solar panel is picking up the strongest signal. But does that mean that this evidence from the solar panel data is somehow more intellectually superior to simply asking the person what they think? The most direct measure is to ask the person outside "do you think it is day or night"? The solar hat is just silly. However, it might at times pick up a situation in which someone is lying or unaware. Even then, such a finding would merely warrant further investigation, and would hardly constitute proof of anything.

It is an obvious truth that changes in thought, emotion, and behaviour, will correlate with, or be the result of, changes in brain activity. Yet it is NOT an obvious truth that a change in regional brain activity--particularly with the relatively crude spacial and temporal resolution permitted by today's technology-- proves that there is a particular change in thought, emotion, or behaviour, or that such measures of brain activity have higher levels of validity than simply having a conversation with someone.

I worry that findings from machine-generated data may so dazzle the audience that it causes unwarranted persuasion to occur, despite the findings being vague or associative. People tend to be impressed by colourful pictures made by expensive machines. We can't let this kind of phenomenon cause us to suspend critical judgment.

A related example of this leaps to mind, in pharmaceutical marketing. There has been a lot of competition out there, in past decades, for companies selling antidepressants and antipsychotics. Typically, in a sales spiel, for a given drug, there would be information given such as:

"most receptor-specific"
or "dual mechanism of action"
or "highest potency"

These facts would certainly be true, and they would have the evidence to prove it. But -- the evidence does not actually exist that these facts are clinically relevant. Whether a drug is "receptor-specific" or not may not really matter at all in terms of how well the drug works. In fact, some drugs such as clozapine, are not "receptor specific" at all, yet work better than the others in its class. "Dual mechanism of action" actually refers to a drug affecting two different receptors (hence, actually it would be less "receptor-specific" yet the phrase is still used as a selling point). Venlafaxine is often marketed this way. Whether or not venlafaxine is a superior antidepressant because of its "duality" is hardly proven, yet the marketing catch-phrase can be compelling to many. And "highest potency" is almost always clinically irrelevant. A drug with smaller "potency" can simply be dosed differently, so that it produces the same effect as a "high potency" drug.

I wholeheartedly support ongoing imaging research, yet I think we need to be careful about inferring too much from the findings at this point.

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