In a given year, more than one in 20 Americans is affected by depression, with some estimates saying as many as one in six will be affected over the course of their life. While researchers are still trying to figure out exactly what causes this mental illness, geneticists have found that genes likely play a significant role in a person’s risk for developing depression. But is depression all in your genes? Not according to a new study out this week, which has shown that there might be hope for preventing depression even in those with a strong family history.
How do genes affect depression?
When mental illnesses like depression, anxiety, or schizophrenia were first described, they were thought to be weaknesses or defects in a person’s character. But more recent research over the past several decades has shown mental illness to be a biological problem like any other illness elsewhere in the body. And like many other biological diseases, depression seems to be influenced by a person’s genetic makeup. In fact, whether or not you have a family history of depression can account for as much as 40 to 50 percent of your risk for becoming depressed. For reference, that’s about the same as the genetic contribution for type 2 diabetes, which you might have heard people say can “run in families.” But it’s clear from studies that genetics aren’t the whole story. Your upbringing and environment play a big part in whether or not you develop certain diseases. These researchers wanted to figure out if the same was true for depression and they used rats to test their ideas.
How did the researchers use rats to study depression?
The research team performed the study using a rat model of depression. It might seem hard to believe that researchers could tell if rats are depressed or not, but they use a standard procedure that measures “despair” in the rats. To do this, they put the rats in a cylinder of water with walls too high for them to climb out. Happy, motivated mice will swim around in the water for long periods of time trying to find an escape before they give up, but depressed rats barely try at all. Most try to swim briefly, but quickly give up and just float in the water waiting to drown or be removed. Several strains of rats have been bred to be at genetically high risk for this rat version of depression so that they’re much more likely to show despair than normal rats.
The team wanted to see how the environment affected depression levels in these at-risk rats compared to rats who weren’t at risk and whether those changes would be reflected in the rats’ gene activity and blood chemistry. The team took two groups of rats and tested their despair levels in the water. They then split them into two groups: one they put in a rat playground with chew toys and structures to hide in or climb on; the other they exposed to periodic stressful situations where they were restrained for two hours a day. After a month in the rat playground or two weeks of stress, the rats were then put in the tub of water and watched for despair. Samples of blood and brain tissue were then taken to look for differences between depressed and non-depressed rats in both environments.
What did the researchers find?
As expected, the researchers found that the depressed rats gave up swimming much faster than the other group of rats. That was also the case in the stressful situation, where the genetically depressed rats were even quicker to despair than when they had started out. But rats in the playground showed a very different response to the water treatment. Both regular rats and depressed rats swam for much longer before giving up, indicating that their levels of motivation were higher than they were at the beginning.
When the researchers looked at chemical and genetic markers of depression in the blood and brain tissue, they found that being in the playground boosted levels of certain chemicals and gene activity to make depressed rats a little more like the non-depressed rats. The stressful situation also increased some levels of chemicals and genetic activity in the non-depressed rats to make them look more like the depressed rats. There wasn’t a perfect match, though, which led the researchers to believe that the interaction between genes and environment is much more complex than they could measure.
How does this apply to me?
While you might not think of rats as a good stand-in for your own mental health, this study shows that even rats with a heavy genetic risk for depression can boost their mood significantly by being in a better, more enriching, and less stressful environment. The researchers think that if this applies to their heavily depressed rats, it probably applies to humans with a family history as well. If you have a family history of depression, improving your environment and the environment of those who share your genes could very well prevent depressive episodes. That could be anything from developing healthy relationships, getting regular exercise, spending some time in the sun or seeing a therapist on a regular basis. The biggest takeaway from this study is that genes don’t predestine your life, even in situations where they might play a big role.
The post Environment Can Trump Genes for Those at Risk for Depression appeared first on The Oz Blog.
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