Electrocortical Effects of Acetaminophen during Emotional Picture Viewing, Cognitive Control, and Negative Feedback.

Acetaminophen, the active ingredient in Tylenol, may have psychological effects, such as reducing social and emotional pain. The current study (N = 173) used electroencephalography (EEG) to extend past research on acetaminophen. Healthy undergraduate students (64.7% women, age M = 18.15, SD = 3.33) were randomly assigned to ingest 1,000 mg of acetaminophen or placebo before completing emotional picture viewing (n = 143), a flanker task (n = 69), and a probabilistic learning task (n = 143) while EEG was recorded. (Sample sizes used for the analyses of each task differ from the total N due to data loss.) We observed standard event-related potentials (ERPs), including emotion-modulated late positive potentials during picture viewing and feedback-related negativity during feedback on the probabilistic learning task. We also observed standard error-related and conflict-related ERPs in the flanker task but could not adequately assess acetaminophen's effect on flanker ERPs due to excessive data loss. Acetaminophen did not alter any of the ERPs, in contrast to predictions based on prior research. Exploratory analyses revealed that acetaminophen reduced the relationship between trait behavioral inhibition system sensitivity and emotion-modulated late positive potentials. Together these findings suggest that a standard dose of acetaminophen did not reliably alter neural indicators of emotional or feedback processing. Instead, preliminary findings from our study suggested that a more nuanced relationship may exist between acetaminophen and individual differences in emotional processing, although this latter finding calls for further replication.