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Brain has its own chemical forces against depression

Staff writer ▼ | October 10, 2015
When it comes to treating depression, how well a person responds to a fake medicine may determine how well they'll respond to a real one, new research finds.
Depression
Placebo power   Depressed people who respond to fake drugs get most help from real ones
Those who can muster their brain's own chemical forces against depression, it appears, have a head start in overcoming its symptoms with help from a medication. But those whose brain chemistry doesn't react as much to a fake medicine, or placebo, struggle even after getting an active drug.

The findings, published in JAMA Psychiatry and made at the University of Michigan Medical School, help explain the variation in treatment response and resiliency that bedevils depression patients and their care teams.

The discovery also opens up the door to new research on how to amplify the brain's natural response in new ways—to improve depression treatment for the estimated 350 million people worldwide who have depression at any given time.

The findings could also help those developing and testing new drugs, helping them correct for the placebo effect that gets in the way of measuring a drug's true effect.

The study comes from a team that has studied the placebo effect for more than a decade, using sophisticated brain scanning techniques in healthy people.

They were pioneers in showing that the brain's natural "painkiller" system - called the mu-opioid system—responded to pain when patients got a placebo. They've also studied the genetic variation that makes certain people more likely to respond to sham painkillers.

For the new study, they studied the brain chemistry of 35 people with untreated major depression, who agreed to try what they thought was a new depression drug, before receiving actual drugs already approved to treat depression.

The team found that participants who reported improvement of depression symptoms after getting the placebo also had the strongest mu-opioid response in brain regions involved in emotion and depression. And these individuals were also more likely to experience even fewer symptoms once they got a real drug.

In fact, response to placebo predicted nearly half of the variation between individuals in total response to the entire study, including actual drug treatment.

"This is the first objective evidence that the brain's own opioid system involved in response to both antidepressants and placebos, and that variation in this response is associated with variation in symptom relief," says the paper's first author Marta Pecina, M.D., Ph.D., a research assistant professor in the U-M Department of Psychiatry and member of the U-M Depression Center.


 

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