LEIPZIG, Germany, Sept. 19 (UPI) -- Selective serotonin reuptake inhibitors, or SSRIs, are one of the most common classes of antidepressants -- used to treat both depression and anxiety symptoms, but the drugs often take up to a month to have positive effects.

In a recent study, however, researchers looking to better understand why SSRIs work for some people and not others -- or for some people much faster than others -- found that a single dose of antidepressant has almost immediate effects on the brain's connectivity.


As part of the new study -- carried out by scientists at the Max Planck Institute for Human Cognitive and Brain Sciences and published this week in the Cell Press journal Current Biology -- researchers gave 22 volunteer patients, who had never suffered from depression, a single dose of a common SSRI called escitalopram, a generic drug first sold under the brand-name Lexapro. A few hours later, researchers scanned the test subjects' brains.

The scans revealed reduced connectivity in all areas of the brain except the cerebellum and thalamus, which exhibited increased connectivity. The cerebellum is central in controlling motor coordination and the thalamus governs signal regulation.

"We were not expecting the SSRI to have such a prominent effect on such a short timescale or for the resulting signal to encompass the entire brain," Julia Sacher, of the Max Planck Institute, said in a press release.

The brief experiment is just an early part of a longer quest to understand how exactly SSRIs operate. Researchers plan to do similar experiments on patients battling anxiety or depression who have early success with SSRIs, and compare their brain scans to patients who fail to respond to the same treatment.

"[This research] could help to better predict who will benefit from this kind of antidepressant versus some other form of therapy," Sacher said. "The hope that we have is that ultimately our work will help to guide better treatment decisions and tailor individualized therapy for patients suffering from depression."