By GEOFFREY MOHAN / latimes.com
A single dose of a popular class of psychiatric drug used to treat depression can alter the brain’s architecture within hours, even though most patients usually don’t report improvement for weeks, a new study suggests.
More than 1 in 10 adults in the U.S. use these drugs, which adjust the availability of a chemical transmitter in the brain, serotonin, by blocking the way it is reabsorbed. The so-called Selective Serotonin Reuptake Inhibitors, or SSRIs, include Prozac, Lexapro, Celexa, Paxil and Zoloft.
The findings could be a first step toward figuring out whether a relatively simple brain scan might one day help psychiatrists distinguish between those who respond to such drugs and those who don’t, an area of mystery and controversy in depression treatment.
Researchers at the Max Planck Institute in Leipzig, Germany, used a magnetic resonance imaging machine to compare connections in the gray matter of those who took SSRIs and those who did not. They were particularly interested in what goes on when the brain is doing nothing in particular.
“We just tell them to let their minds wander and not think of anything particularly dramatic or upsetting,” said neuroscientist Dr. Julia Sacher, a co-author of the study published online Thursday in the journal Current Biology.
They created 3-D maps of connections that “matter” to gray matter: interdependence, not just anatomical connection. They relied on a discovery in the late 1990s that low-frequency brain signaling during relative inactivity, such as daydreaming, is a good indicator of functional connectivity.
When more serotonin was available, this resting state functional connectivity decreased on a broad scale, the study found. This finding was not particularly surprising — other studies have shown a similar effect in brain regions strongly associated with mood regulation.
But there was a two-fold shock: Some areas of the brain appeared to buck the trend and become more interdependent. And all the changes were evident only three hours after the single dosage.
“It was interesting to see two patterns that seemed to go in the opposite direction,” Sacher said. “What was really surprising was that the entire brain would light up after only three hours. We didn’t expect that.”
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