Acetaminophen is an effective painkiller, but it could also be blocking our brain’s ability to detect errors.
“Past research tells us physical pain and social rejection share a neural process that we experience as distress, and both have been traced to same part of the brain,” says Dan Randles, postdoctoral fellow at the University of Toronto.
Recent research has begun to show exactly how acetaminophen inhibits pain, while behavioral studies suggest it may also inhibit evaluative responses more generally. Further, research has shown that people are less reactive to uncertain situations when under the effect of acetaminophen.
“The core idea of our study is that we don’t fully understand how acetaminophen affects the brain,” Randles says. “While there’s been recent behavioral research on the effects of acetaminophen, we wanted to have a sense of what’s happening neurologically.”
To test the idea two groups of 30 people were given a target-detection task called the “Go or No Go.” Participants were asked to hit a Go button every time the letter F flashed on a screen but refrain from hitting the button if an E flashed on the screen. “The trick is you’re supposed to move very quickly capturing all the GOs, but hold back when you see a No Go,” Randles says.
Each participant was hooked up to an electroencephalogram (EEG), which measures electrical activity in the brain. The researchers were looking for a particular wave called Error Related Negativity (ERN) and Error Related Positivity (Pe). Essentially what happens is that when people are hooked up to an EEG and make an error in the task there is a robust increase in ERN and Pe.
One group, which was given 1,000 mg of acetaminophen—the equivalent of a normal maximum dose—showed a smaller Pe when making mistakes than those who didn’t receive a dose.
“It looks like acetaminophen makes it harder to recognize an error, which may have implications for cognitive control in daily life,” Randles says.
Cognitive control is an important neurological function because people are constantly doing cognitive tasks that flow automatically like reading, walking, or talking. These tasks require very little cognitive control because they are well mapped out neurological processes, Randles says.
“Sometimes you need to interrupt your normal processes or they’ll lead to a mistake, like when you’re talking to a friend while crossing the street, you should still be ready to react to an erratic driver,” Randles says.
“The task we designed is meant to capture that since most of the stimuli were Go, so you end up getting into a routine of automatically hitting the Go button. When you see a No Go, that requires cognitive control because you need to interrupt the process.”
An unexpected and surprise finding was that those who received an acetaminophen dose appeared to miss more of the Go stimuli than they should have. Randles plans to explore that more closely to see if acetaminophen is actually causing people to “mind wander” and become distracted.
“An obvious question is if people aren’t detecting these errors, are they also making errors more often when taking acetaminophen?
The research is published in the journal Social Cognitive and Affective Neuroscience.
Source: University of Toronto