Recent advances in brain scanning may bring welcome news to people with depression.
Two new types of MRI appear able to spot distinct brain characteristics of the condition.
The researchers say that their findings deepen knowledge about how depression affects the brain and should lead to better treatments.
One of the new types of MRI reveals differences in the blood-brain barrier (BBB), and the other highlights differences in the brain’s complex network of connections.
Scientists recently used the novel MRI technologies in people with or without major depressive disorder (MDD).
Presentations on the findings are featuring this week at RSNA 2019, the 105th annual meeting of the Radiological Society of North America, which is taking place in Chicago, IL.
According to the World Health Organization (WHO), depression affects more than 264 million people worldwid.
Depression and BBB
Depression is more than the feelings of sadness that most people experience in day-to-day life. It can be a serious health condition, especially when symptoms persist. The most severe forms of depression can lead to suicide.
Loss of interest in daily activities, feelings of hopelessness, and fatigue are some of the main symptoms of MDD.
While scientists know that brain changes accompany the symptoms of MDD, their understanding of the underlying mechanisms is insufficient to meet the urgent need for better treatments.
Kenneth T. Wengler, Ph.D., a researcher in the Department of Psychiatry at Columbia University, in New York, was the first author of the study that examined links between MDD and changes to the BBB.
“Unfortunately,” says Wengler, “with current treatments [for MDD] there is a large chance of relapse or recurrence.
To develop new, more effective treatments, we must improve our understanding of the disorder,” he adds.
The BBB is a unique set of properties in the brain’s blood vessels that allow them to control the movement of molecules and cells between them and the tissues that they serve.
The BBB shields the brain from harmful toxins and pathogens that might be in the bloodstream.
Reduced water permeability in the BBB
Wengler and colleagues used a new type of MRI that they had developed themselves. The method, which they named “intrinsic diffusivity encoding of arterial labeled spins,” or IDEALS, allows scientists to investigate the movement of water across the BBB.
They used the new MRI to investigate the BBBs of 14 individuals with MDD and 14 healthy control participants.
Scans of the participants’ brains revealed that those with MDD had reduced water permeability in their BBBs; water moved less readily from their blood vessels into brain tissue than it did in the healthy controls.
The difference in BBB water permeability was particularly marked in two brain regions: the amygdala and the hippocampus. Previous imaging research in people with MDD has also highlighted these two regions.
“We observed disruption of the blood-brain barrier in gray matter regions known to be altered in [MDD],” Wengler explains.