PLEs in response to d-amphetamine and caffeine
The present study showed that d-amphetamine (0.45 mg/kg, PO), but not caffeine (200 mg), increased PLE scores. Previous reports showed that the level of dopamine released after dexamphetamine administration correlates with PLE scores [In the present study, caffeine did not significantly affect PLE measures. However, we predicted that caffeine might slightly increase schizotypy scores as dopamine mediates some of the behavioural effects of adenosine antagonists [There are several double-blind placebo-controlled studies in healthy participants that showed caffeine consumption increases subjective effects (such as arousal) [The present results also showed that caffeine increased physiological (blood pressure) measurements without having effects on WM, indicating that the drug was active during cognitive tasks. Previous studies reported that low to moderate doses of caffeine increase systolic and diastolic blood pressure ([