The usual reason to use a pain reliever is (obviously) to dull physical aches, but there’s also an off-label use that’s becoming more widely known: Acetaminophen — the active ingredient in Tylenol — appears to alleviate emotional pain, like the deep heartache that comes with a breakup, for example. But a new study, published online this week in Psychological Science, takes that finding one step further, suggesting that pain relievers might numb your emotional response to positive events, too.
To test their theory, Geoffrey R. O. Durso and a team of researchers at Ohio State University gave about half of their 82 undergraduate participants 1,000 milligrams of acetaminophen — for reference, one Extra-Strength Tylenol has 500 milligrams — in liquid form; the other half got a placebo. (Neither group knew which one they’d taken.) Both sets of students were shown 40 different photos designed to elicit either positive emotions (adorable children playing with adorable kittens!), negative emotions (malnourished and crying children, sans kittens), or little emotion at all (a single cow standing in a field). As they looked at the photos, the students rated how positive and negative each photo was; they also rated how strong of an emotional response they felt when viewing the photos.
Overall, the students who’d taken the acetaminophen rated the positive images as less positive and the negative images as less negative, as compared to the students in the placebo group. (The differences in ratings weren’t huge, but they were statistically significant — for example, those who’d taken the pain reliever rated positive photos at 2.62, on average, on a scale from -5 to 5, while kids in the placebo group gave it a 3.18.) Similarly, students who’d been given the placebo reported stronger emotional reactions to both happy and unhappy images, compared to the placebo group — for the most jarring images, the difference was almost a full point on a 10-point scale.
It’s not exactly clear why or how the over-the-counter drug ingredient might be messing with the way people experience emotions, but research has suggested that acetaminophen may decrease activity in the insular cortex, the region of the brain associated with emotion regulation. People whose brains have been damaged in this area, for example, seem to experience relatively steady emotions — their lows aren’t as low and highs aren’t as high, when compared to people without injury to this region. (Kind of like a neurological representation of Jerry Seinfeld as Even Steven.) Whatever acetaminophen is doing, it might have something to do with the insular cortex.
Then again, maybe not — it’s still relatively early days for this area of research; also, one study published last fall suggested that the experiences of emotional and physical pain do not register the same way in brain-scan imagery. But the implications of this current finding do seem to hint that acetaminophen’s apparent capacity to dampen pain — physical or emotional — is only part of the story. As the study authors write, “rather than being labeled as merely a pain reliever, acetaminophen might be better described as an all-purpose emotion reliever.”