Your friends are doing a lot more for you than you think—and now science proves it. A 2012 review by Meyer-Lindenberg and Tost, which summarizes evidence from other studies, suggests that social stressors and genes may interact to predict mental illnesses.
Meyer-Lindenberg and Tost list three strong associations between mental illness and environmental factors: early childhood neglect or abuse, an upbringing in an urban environment, and being a first- or second-generation immigrant (in any country). These environmental factors are considered “social stressors”; social stress is stress that develops from relationships with others.
A phenomenon called “social defeat”, where a person feels like an outsider, may be shared by these three environmental factors. The term “social defeat” was first applied to animals in experiments that focus on resident-intruder relationships. An animal would be placed in the cage of an animal of a different species in way that induced some sort of non-lethal conflict. Sometimes, after a clash resulted, the first animal was then kept in a cage next to the resident of the cage it had been placed in. The researchers would then observe cues of acute stress throughout the experiment, and determine which animal was the dominant one.
A similar phenomenon occurs in humans when an outsider or intruder enters a new community. Social defeat is usually prominent when children or immigrants are unable to make or keep friends in their new environment. Social defeat can lead to depression, and studies show it can even be associated with an increased risk of schizophrenia.
But Meyer-Lindenberg and Tost also saw that certain genetic variants can exacerbate the effects of environmental factors. They identified these genetic variants in three genes (the oxytocin receptor gene, the monoamine oxidase-A gene, and the CACA1C gene). All three genes influence the brain’s biochemistry—and all three influence how the brain deals with social situations. The oxytocin receptor gene, for example, receives chemical signals from the hormone oxytocin. Several studies have linked oxytocin with anxiety levels, maternal behaviour, and social recognition. Oxytocin has also been linked to how people manage trust and empathy in social situations. Some evidence also shows that oxytocin can boost tribal-type behaviour and the exclusion of outsiders.
The three genes are considered “risk variants” for mental illness. They affect the brain in a way that makes some people prone to mental illness.
Together, the evidence of social stressors and that of genetic risk variants point to a seemingly simple conclusion. People who feel alienated are at risk for mental illness—especially if they carry the genetic variants that exacerbate the effects of their isolation.
So what should we do about it? Positive environments for children are key. Pharmacology can also help. Taking oxytocin, for example, can be used to relieve anxiety when used in conjunction with psychotherapy.
But even perceived alienation or discrimination can be harmful. Whether perceived or real, the consequences of feeling like an outsider can lead to changes in our neurobiology.
In the end, it still comes down to relationships. Go out and make some friends. You can tell them that you just might be saving both of you from schizophrenia.