fMRI Links Post-Stroke Depression to Brain Impairment

Using fMRI, researchers have found a strong association between post-stroke depression and functional brain impairment, said researchers in a study published today online in the journal Radiology.

Studying 24 patients, researchers from the University of Bordeaux in Bordeaux, France, assessed a group of brain structures in the default-mode network (DMN). Previous studies had looked at post-stroke abnormalities and dysfunction in specific regions of the brain.

“The default-mode network is activated when the brain is at rest,” said lead researcher, Igor Sibon, MD, PhD, a professor of neurology at the university. “When the brain is not actively involved in a task, this area of the brain is engaged in internal thoughts involving self-related memory retrieval and processing.”

The patients underwent a resting-state functional magnetic resonance imaging (fMRI) 10 days after having had a mild to moderate ischemic stroke. Stroke severity was based on the US National Institutes of Health Stroke Severity scores, as well as other scores. They were also evaluated for depression and anxiety at 10 days and again at three months post-stroke.
Using clinical findings, the researchers found that 10 patients had minor to moderate depression and 14 had no depression. The fMRI findings showed that there was an association between modifications of connectivity in the DMN 10 days after the stroke.

There was no correlation between the depression scores and functional connectivity at 10 days, but there was a positive correlation between the anxiety score and the rest functional connectivity index of the right and left middle temporal cortex. In addition, there was a positive correlation between the left middle temporal cortex rest functional connectivity index with both depression and anxiety.

“We found a strong association between early resting-state network modifications and the risk of post-stroke mood disorders,” said Sibon. He acknowledges that more research needs to be done, but points out, “These results support the theory that functional brain impairment following a stroke may be more critical than structural lesions.”