A new study from Northwestern University reports that genetics do not create a predetermined destiny when it comes to knowing whether someone will, or will not, experience depression in his or her lifetime. This is good news and bad news.
On the bright side, the researchers found that immersing rats, who had been bred for depression-like behavior for 33 generations, into engaging and playful environments brought them out of extreme despair. The changes were so dramatic that some of their blood biomarkers for depression changed to non-depressed levels.
On the flip side, when a control group of genetically “non-depressed” rats were exposed to prolonged, intense environmental stress, it caused their blood biomarkers for depression to convert to levels seen in the genetically depressed rats. Based on these findings, the researchers believe that genes and environment cause depression by different molecular pathways and that nurture can override nature in depression.
The March 2016 study, “Nature and Nurture: Environmental Influences on a Genetic Rat Model of Depression,” was published today in the journal Translational Psychiatry. Although this is an animal study, the genetic rat model of depression is biologically similar to human depression.
In a statement, Eva Redei, professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine, and lead investigator of the study, said,
“The environment can modify a genetic predisposition to depression. If someone has a strong history of depression in her family and is afraid she or her future children will develop depression, our study is reassuring. It suggests that even with a high predisposition for depression, psychotherapy or behavioral activation therapy can alleviate it.”
The study also found genetic influences and environmental influences on depression likely work through different molecular pathways. Rats bred for depression, and rats that were depressed due to their environment, showed changes in the levels of entirely different blood markers for depression. Being able to differentiate between the two types of depression could eventually lead to more precise psychotherapy treatments and antidepressant medications.
There Will Be Sunbeams In Your Soul Again
Over the years, I’ve written candidly about my own battles with depression. I’ve had two major depressive episodes in my lifetime. When I look at this research through the lens of my own life experience, and pretend that I was a guinea pig in this experiment, I can anecdotally corroborate the findings of this study.
I’ve always believed that I have a genetic predisposition for depression, but with hindsight, it’s clear that my environment played a huge role in plunging me into a clinical depression—which I describe as “blackness within blackness.” Later, a change in environment brought me out of depression by beaming sunbeams into my soul.
As an example, I was a very happy teenager until my parents’ marriage started to fall apart. I was sent off to a stuffy boarding school in Wallingford, Connecticut with a dean who made me feel “less than” in many ways. I felt so alone, bullied, trapped, and like a black sheep at boarding school that I plummeted into a deep depression that almost caused me to self-destruct.
Luckily, after high school, I went off to Hampshire College in Amherst, Massachusetts which fosters a “free to be… you and me” culture. By the end of my first semester of college, I was the happiest I’d ever been in my life. I agree with Redei’s assessment, “You don’t have people who are completely genetically predisposed to depression the way the rats were. If you can modify depression in these rats, you most certainly should be able to do it in humans.”
It’s encouraging to know that your disposition for depression isn’t set in stone. However, it’s also important for parents, educators, and policymakers to understand the life-changing impact environment can have on someone’s mental health.
For example, in a Psychology Today blog post, “Kids and Classrooms: Why Environment Matters,” I wrote about the potential backlash of not providing public schools with the funding needed to create safe, clean, enriched learning environments for our children. The new research from Northwestern shows that even children who are hardwired to be resilient and optimistic can be beaten down and rewired for depression.
Environmental Stress Can Make Genetically Non-Depressed People Depressed
In the Northwestern study, Redei and colleagues were curious to see if they could alter the rats’ genetically caused depression by changing their environment. To accomplish this, they took depressed rats and put them in large cages with lots of toys to chew on and places for them to hide and climb. They describe the environment as “sort of a Disneyland for rats.” The rats were kept in this utopian playground for one month. “We called it rat psychotherapy,” Redei said, “because the enrichment allows them to engage with the environment and each other more.”
After a month in the playground, the researchers found that the rats’ depressive behavior was dramatically reduced. To prove this, the rats were placed in a tank of water that is used as a way to measure for depression.
Typically, non-depressed control rats will swim around curiously while they’re actively looking for a way to escape. On the other hand, depressed rats tend to be complacent and apathetic. They simply float in the water, making no effort to find a way out. The good news is that after just a month in the playground, the genetically depressed rats energetically paddled around the tank, eagerly looking for an exit.
Conversely, the Northwestern scientists wanted to see if environmental stress could trigger depression in rats who had been bred to be the ‘non-depressed’ control group of the experiment. The control rats were subjected to a psychologically stressful situation, which involved being restrained for two hours a day for two weeks.
After two weeks of prolonged stress, the control rats also displayed depressive behavior and inertia when placed in the water tank. They, too, passively floated in the water, showing the same behavior as the genetically depressed rats, and didn’t try to escape. The prolonged environmental stress caused some of the blood biomarkers for depression to change from non-depressed levels to levels seen in genetically depressed rats.
Conclusion: Your Genes Don’t Determine Your Depressive Destiny
Although the exact causes and effective interventions for depression remain enigmatic, these new findings offer valuable clues for creating better ways to diagnose and treat depression.
This research should serve as a reminder that nobody is immune from getting depressed. If you are suffering from depression, reach out and ask for help. And, if you’re in a position to change your environment, this research shows that doing so could create a chain reaction and upward spiral that could alter your biomarkers for depression.
The next step for the Northwestern researchers is to find out if the biomarkers actually cause behavioral changes in response to the environment. Redei concluded, “If so, then perhaps we can find novel drugs to change the level of biomarkers in depressed rats to those of the non-depressed controls and, thus, discover new antidepressant medications.”