Thursday, July 19, 2007

Placebo Effect

We’ve talked here some about the “cult of pharmacology” and the importance of understanding placebo effects in our assessments of drugs, their use, and the stories we tell about their capacity to “enslave” us. In fact, the idea of a “placebo text” that underlies the context of drug use and users, influencing when, how, and even whether a drug will have the same physiological effect on different individuals or the same individual, is key to the reality of drug use in this country. Here’s a good article on recent research on placebos and how they work, based on the now ubiquitous brain scans. Their basic finding?

Specifically, the research finds strong links between an individual's response to a placebo "painkiller", and the activity of the neurotransmitter known as dopamine in the area of the brain known as the nucleus accumbens. That's a small region at the center of the brain that's involved in our ability to experience pleasure and reward, and even to become addicted to the "high" caused by illicit drugs.

The new research, published in the July 19 issue of the journal Neuron, builds on research previously published by the same U-M team in 2005. That study was the first to show that just thinking a placebo "medicine" will relieve pain is enough to prompt the brain to release its own natural painkillers, called endorphins, and that this corresponds with a reduction in how much pain a person feels.

And here’s how it applies to the effects of “pleasure” drugs that affect dopamine systems. Just replace the pleasure from the “money game” in the experiment with other druggie contexts.

The fMRI scans, which were performed on different days from the PET scans, revealed additional information about how individual expectations correlated with their placebo response. Each volunteer had an fMRI scan that looked at blood oxygenation throughout their brain, which allows researchers to spot areas where neurons (brain cells) are especially active as the individual performs a task or plays a game. In this case, the task was a very simple gambling game, in which subjects were scanned while expecting varying levels of a monetary reward or no reward.

As in the PET scans, the nucleus accumbens was a hotbed of activity as the volunteers were told how much money they could win or lose in the next round; as they waited for the round; and as they pressed the button and learned if they had succeeded in winning or avoiding losing money.

Then, the researchers compared the PET and fMRI scans for the volunteers who had had both types of scan. They also compared the ratings of anticipated placebo effect, the analgesia induced by the placebo during the pain studies, and the emotional changes associated with it. They found that those who expected a placebo to help them and got greater benefit from it (more analgesia, better emotional state) were also those who had the most activity in their nucleus accumbens during the anticipation of receiving a reward in the fMRI money game.

This kind of research is revolutionizing the ways the health field approaches drug use and abuse. The question is if/whether any of their findings will ever find their way into intelligent responses in corr sent.

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