Earlier this year, the COVID-19 pandemic resulted in shortages of acetaminophen. This is not surprising, because like the nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen, acetaminophen (or paracetamol; brand name Tylenol) is usually used for pain and fever reduction.
However, an article published in the July issue of Social Cognitive And Affective Neuroscience, by Keaveney and colleagues from the Ohio State University and the University of Oregon Eugene, reports evidence that acetaminophen also increases risk-taking behavior.
Risk-taking and acetaminophen: Sample and methods
Study 1: 142 undergraduate students (76 men; the average age of 19 years) took part in a double-blind placebo-controlled investigation. The dose given was 1000 mg. After about 45 minutes (sufficient time for drug uptake), participants completed a questionnaire that measured their risk/benefit perceptions. The questionnaire asked them to make risk and benefit judgments regarding the societal impact of a variety of items (e.g., pesticides).
Participants then completed the Balloon Analog Risk Task (BART). This computerized task involves pumping balloons and earning digital money. With each pump, there is a risk of the balloon exploding and the participants losing all they have earned on that trial. So, BART measures risk-taking.
Study 2: 189 undergraduates (109 men; average age: 19 years). Again, acetaminophen was given and BART used to measure risk-taking. However, instead of the previous questionnaire, risk and benefit perceptions were evaluated using the revised Domain Specific Risk-Taking Scale (DOSPERT). This scale uses scenarios (e.g., sports betting) to measure risk. Since these items require participants to judge the benefits and risks that would affect them personally, the researchers hoped the scale would be more emotionally stimulating than one used in the first investigation.
Study 3: 215 (91 men); average age, 19 years. Similar procedures, instruments, and interventions were used with a few exceptions (e.g., a new drug formulation and a novel platform for BART).
Risk-taking and acetaminophen: Results
The results from the first two experiments showed participants who took acetaminophen, compared to the placebo, took significantly more risks on BART. Combining the results of the three investigations, the authors found a significant main effect of acetaminophen on risk-taking.
In the first investigation, however, acetaminophen did not lower risk perception, perhaps because the items on the questionnaire were not particularly emotionally stimulating. But in the second investigation, using DOSPERT, acetaminophen did reduce the perceptions of risk, and this mediated increased risk-taking observed on BART.
Only Study 3 did not find the same effects of acetaminophen on risk-taking, perhaps due to the novel BART software or the new drug preparation used.
The researchers concluded, “acetaminophen may reduce negative affect and risk perception in turn and, thereby, increase risk-taking.”
In a way, this finding is not surprising because research has suggested that, aside from pain relief and fever reduction, acetaminophen (Tylenol) may influence a variety of psychological processes. The authors cite these examples: Acetaminophen may reduce “hurt feelings,” “meaning threats,” “distress over another’s suffering,” “loss aversion,” and emotional reactivity to negative and positive images. And the present research suggests acetaminophen might increase risk-taking behavior too. But why?
Why might acetaminophen increase risk-taking?
As tested in the present research, one possible mechanism of acetaminophen’s effects on risk-taking involves the effects of emotions on the perception of risk.
For instance, the risk-as-feelings theory suggests anticipatory emotions may drive risk-related behaviors. In other words, people use their feelings as a mental shortcut to help them make decisions, especially in imminently risky or emotionally engaging situations.
To illustrate, a person looking at a picture of a beautiful and aerodynamic motorcycle might feel the risk of having an accident while riding it is negligible (and more than offset by all the benefits of riding the motorcycle). In contrast, the same person looking at a picture of a nuclear plant might feel nuclear power is highly dangerous and offers very few benefits. In both cases, the person has relied on emotions to make judgments about risk.
Objects and situations that happen to elicit positive emotions are often seen as involving little risk and offering many benefits, while ones that elicit negative emotions are judged as having high risk and few benefits.
Therefore, acetaminophen could increase risk-taking by reducing negative feelings, and as a result, risk perception.
Concluding thoughts on acetaminophen use
As for the population-level implications of these findings, we need to consider this: Almost one in four Americans take acetaminophen on a weekly basis.
What might be the consequences of an increase in risk-taking, as a result of acetaminophen use, when it might potentially affect millions of Americans? While we should not conclude too much about the possible effects based on a few studies, the authors suggest that the implications are worth considering: As they state, for example, “many patients in the hospital have acetaminophen in their systems when presented with risk information and asked to make potentially life-changing risk assessments such as whether or not to do invasive surgery.”