A "New Type of Depression" May Explain Why Some Treatments Don't Work

While it takes time and persistence, seven in ten adults with major depression usually find a treatment that helps. But this still leaves 30 percent of clinically depressed individuals searching for an intervention that can change their life. This year, scientists reported that the millions of people who don’t benefit from existing treatments may be in need because they have a different type of depression altogether.

Approximately 90 percent of antidepressants are designed to address the fact that depressed people have abnormal levels of the brain chemicals serotonin and norepinephrine. This suggested to a team from Hiroshima University that there must be another explanation for what could cause depression. In the July edition of Neuroscience, they suggest that one type of depression might be driven by a protein called RGS8, which influences the parts of the brain involved with movement and mood regulation.

This story is #4 on Inverse’s 25 Most Surprising Human Discoveries Made in 2018.

In their experiment, they compared the behavior of a group of mice genetically engineered to have more RGS8 in their nervous system to that of a control group. They forced both groups to swim — a commonly used way to assess depressive behaviors in animals — and found that the mice with more RGS8 were immobile for shorter amounts of time than the others. That is, they swam to survive.

This suggested to the team that the mice with high RGS8 levels were less depressed than the others.

Later, those mice received a drug that stops the hormone receptor MCHR1, which is controlled by RGS8, from working. This was meant to mimic what might happen if the effects of RGS8 were dampened — much as they would be in a person whose depression is caused by low RGS8. The hippocampus cells of those mice ended up having longer-than-usual cilia — organelles involved with cellular communication that are linked to obesity, kidney disease, and retina disease when they are dysfunctional

The scientists concluded that having less RGS8 means increased depressed behavior, a phenomenon that hadn’t been witnessed before. Study co-author and graduate student Yumiko Saito said that “these mice showed a new type of depression.” This work paves the way for scientists to develop new antidepressant drugs to maintain RGS8 levels, hopefully offering relief to the many people who haven’t found a successful treatment so far.

As 2018 winds down, Inverse is highlighting 25 surprising things we learned about humans this year. These stories told us weird stuff about our bodies and brains, uncovered insights into our social lives, and illuminated why we’re such complicated, wonderful, and weird animals. This story was #4. Read the original story here.