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Could a popular painkiller hamper our ability to notice erors?

pain relief

Pain, it’s a pain, it always seems to find ways to pop up when you least expect it, enter non-aspirin! Better known as acetaminophen, it has been known for centuries that is an effective painkiller. Since it is over the counter most people don’t give it a second thought, but according to a new study, it could also be impeding error-detection in the brain.

As unbelievable as this may sound, this is actually the first neurological study to look at how acetaminophen could be inhibiting the brain response associated with making errors. Which would seem like someone somewhere dropped the ball, but maybe they didn’t see an error because they were using acetaminophen that day.

“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, first author.

It has only been recent research that has started to show how exactly acetaminophen inhibits pain; behavioural studies suggest it may also inhibit evaluative responses more generally.

“The core idea of our study is that we don’t fully understand how acetaminophen affects the brain,” says Randles.

“While there’s been recent behavioural 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 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,” says Randles.

Because we want to see what happens on a neurological level, 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) — which is basically the brains duh moment you have after it realizes you were wrong.

They were also looking for Error Related Positivity (Pe) — typically you will only get a Pe response when you actually realize the error occurred, hence the neuro-high five Pe response. 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, suggesting that acetaminophen inhibits our conscious awareness of the error.

“It looks like acetaminophen makes it harder to recognize an error, which may have implications for cognitive control in daily life,” says Randles.

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, notes Randles.

“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,” explains Randles.

“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.”

Like any good study of this type it was double blind, so neither the researcher running the study nor the participant knew whether they had been given a placebo or acetaminophen. This means the researchers wouldn’t bias the EEG readings based on what they were expecting to find.

Interestingly, the researchers also found something that was unexpected. A surprise finding that the researchers plan to explore more closely, the team found that those who received an acetaminophen dose appeared to miss more of the Go stimuli than they should have. This could have been a statistical anomaly, but it warrants further research. The researchers are planning to expand on the error detection aspect of the research to see whether acetaminophen is possibly 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? This is the first study to address this question, so we need more work and ideally with tasks more closely related to normal daily behaviour.”

Randles, D., Kam, J., Heine, S., Inzlicht, M., & Handy, T. (2016). Acetaminophen attenuates error evaluation in cortex Social Cognitive and Affective Neuroscience DOI: 10.1093/scan/nsw023

One response

  1. Ugh. The only pain reliever I use. The rest I have already sworn off. I’ll hang with my trusted go-to, even if it has the potential to debillitate me.



    April 9, 2016 at 7:53 pm

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