By Timothy Deckman

Marijuana use is hot topic of debate recently. With states legalizing recreational use, more states putting medicinal use up for referendum, and even the NFL reconsidering its disciplinary policy on the issue, it is important for researchers (and data) across specialties to be a part of this debate. This project, published in Social Psychological and Personality Science, focuses marijuana’s ability to dampen social pain among the lonely.

Before getting into the nuts and bolts of each study, first let’s start with a little background on social and physical pain. Social pain can colloquially be characterized as “hurt feelings.” During human history, we developed a system of social pain to signal trouble and to avoid the death sentence of exile from our social groups. Studies show that experiencing social exclusion leads to both poor physical and psychological well-being.

The social pain network was co-opted directly on top of our extant physical pain network. Functional MRI research confirms that being socially excluded also activates the physical pain centers in the brain. If experiencing pain in one pain network induces pain in the other network, then anything that lessens our physical pain should lessen our social pain. Research makes this point as people who took the pain killer acetaminophen (Tylenol©) felt less social pain in their daily life over time. The next question becomes: can other drugs which, like acetaminophen reduce physical pain, also reduce social pain?

But, how does acetaminophen work? Acetaminophen has been recommended by physicians as an over-the-counter pain reliever for over a century. It wasn’t until recently (2006 – 2008) however, that the mechanism of action has been firmly established. Research has identified the cannabinoid 1 (CB1) receptor as central to the pain relieving effects of acetaminophen.

Knowing that acetaminophen is a cannabinoid makes it a little less surprising that marijuana was the next drug tested to see if it might also have the same impact on social pain. The major psychoactive ingredient in marijuana is tetrahydrocannabinol (THC). THC works indirectly through CB1 and relieves physical pain. Our hypothesis was that marijuana would act the same as acetaminophen (because they have a similar mechanism of action) in buffering people from negative consequences of social pain. We designed four studies using various methodologies to test our hypothesis.

Studies 1 and 2 used a nationally representative dataset to test the relationships between loneliness, marijuana use, and the negative consequences of social pain. The first study showed that marijuana buffers lonely people from low feelings of self-worth and also low self-rated mental health. The second study went beyond self-ratings and found that marijuana also reduces the link between loneliness and major depressive episodes (clinically diagnosed). These studies offer preliminary support for our hypothesis, but are correlational in nature.

The next study used a longitudinal design to control for baseline levels of depression when looking for changes in depression over time. We looked at data from a high school that tracked students over the course of three years. We found that marijuana use buffers lonely participants from feelings of depression two years later. People who were lonely and didn’t use marijuana were much more depressed than those who were lonely and did use marijuana. This study added validity to our claim by controlling for baseline depression and also establishing that these effects were present over time. However, none of our first three studies employed experimental control.

In the fourth study, we used a computer game to simulate social exclusion. Participants were randomly assigned to either social exclusion or control conditions. We found that participants who had used more marijuana experienced less distress as a result of the exclusion manipulation. After four studies, we found that marijuana buffered the lonely from: negative self-ratings of self-worth and mental health, depression over time, and even distress following exclusion.

While it may seem that we are making a case for marijuana use, the authors of this study in no way condone the use of marijuana. There are many well-documented negative consequences from marijuana use. However, this research offers some insight as to why marijuana is the most widely used illicit drug in America. Our results suggest that many people may be using marijuana as a way to cope with feelings of social pain and loneliness.