New research suggests one reason for the popularity of pot may be that it helps people cope with the pain of loneliness.

Why smoke marijuana? Users would probably reply that numbed-out bliss is its own reward. But if smoothing out the harsh edges of reality is your goal, what bruises are you attempting to avoid?

Newly published research suggests that, at least for some, the answer is: The intense discomfort of social exclusion.

“Marijuana has been used to treat physical pain,” reports a research team led by University of Kentucky psychologist Timothy Deckman, “and the current findings suggest it may also reduce emotional pain."

Given the drug's long-term health effects, “This may reflect a poor way of coping,” the researchers write in the journal Social Psychological and Personality Science, “but it may also explain some of the widespread appeal of marijuana.”

Avoiding social pain by smoking pot is not unlike taking antacids to relieve stomach pain, as opposed to addressing its root cause.

Deckman and his colleagues are building on two lines of recent research: One that shows the pain of social exclusion is more intense than we previously realized, and another revealing that physical pain and emotional pain travel similar pathways in the brain.

A 2010 paper by C. Nathan DeWall, a co-author of this new study, found the use of acetaminophen (i.e., Tylenol) reduces the pain of social rejection. A much-publicized follow-up earlier this year found that use of that same painkiller can reduce existential angst.

Since acetaminophen and marijuana work through similar brain receptors, the researchers wondered whether pot similarly softens the pain of exclusion. They describe four experiments providing evidence that indeed it does.

The first incorporated data on 5,631 Americans, who reported their level of loneliness, described their marijuana usage (if any), and assessed their mental health and feelings of self-worth. Not surprisingly, the researchers found a relationship between loneliness and feelings of self-worth, but it was significantly weaker for regular pot smokers.

“Marijuana use buffered the lonely from both negative self-worth and poor mental health,” the researchers write.

Another experiment, featuring 537 people, found those who were experiencing social pain were less likely to have suffered a major depression in the past year if they smoked pot relatively frequently.

Still another experiment, featuring 225 people, used the computer game Cyberball to create an immediate experience of social exclusion. Half the participants in the three-person game received the ball twice early on, and then never again during the course of the game. They then reacted to a series of statements designed to assess whether their need for self-esteem and belonging felt threatened—statements such as, “I had the feeling that the other players did not like me.”

The results: Those who smoked marijuana relatively frequently felt less threatened than those who smoked it less frequently, or not at all.

Together, these studies show that “marijuana use consistently buffered people from the negative consequences associated with loneliness and social exclusion,” Deckman and his colleagues conclude. But buffers are of limited usefulness.

“Humans have a fundamental need to belong,” the researchers note. “Hurt feelings motivate us to fix our relationships and re-establish social connection.”

In that sense, avoiding social pain by smoking pot is not unlike taking antacids to relieve stomach pain, as opposed to addressing its root cause (such as stress or obesity). It does work, at least for a while, but it’s also a way to avoid dealing with the underlying issue.

In the long run, weed is a poor substitute for "we."