Caffeine is widely consumed for its stimulant properties and has been
proposed as a potential cognitive enhancer in both healthy populations and
individuals with attention-deficit/hyperactivity disorder (ADHD). However, research
on caffeine's effects in adults with ADHD remains limited. The present study
investigated whether caffeine reduces distractibility in adults with varying ADHD-like
traits using a modified Eriksen Flanker Task. Twenty-two participants, stratified into
low- and high-ADHD-like trait groups, were randomly assigned to placebo, low-dose,
or high-dose caffeine in a single-blind design. Results revealed no main effects of caffeine or dosage, and no interaction
with ADHD-like traits. Instead, a significant group effect emerged: participants with
low ADHD-like traits demonstrated greater improvements in reaction time compared
to those with high traits. These findings suggest that baseline attentional control
accounted for performance differences. Overall, caffeine may not uniformly enhance
attentional control, underscoring the importance of individual differences when
evaluating stimulants as cognitive enhancers.