Propranolol, a nonselective beta blocker, produces noradrenergic blockade with central and peripheral nervous system effects. While propranolol is often prescribed for hypertension, it is also commonly prescribed for situational anxiety (stage fright, test anxiety, etc) due to its central activity. Previous work in this lab has examined the effect of propranolol on cognitive flexibility tasks. In a previous study in this lab, performance on simple cognitive flexibility tasks was shown to be increased in autistic individuals who take propranolol, whereas controls only exhibited improvement in difficult tasks. Our aim was to examine other possible benefits of propranolol on cognition. To do this, we compared performance on verbal fluency tasks, which require cognitive flexibility, between autistic and control individuals, under propranolol and placebo conditions.
Furthermore, it is characteristic of individuals with autism to exhibit poor eye contact with others from an early age. Recent physiological evidence suggests that direct eye contact may be stressful to those affected by autism. Stress is well known to activate the noradrenergic system. Therefore, an agent that could reliably decrease the stress related to eye contact by acting to block noradrenergic activation may be beneficial to those affected with autism. Thus, since decreased eye contact in autistic individuals may be linked to stress and propranolol is known to decrease social stress, we proposed to determine whether autism-affected individuals would increase their eye contact when given propranolol. We hypothesized that propranolol administration, through its action of decreasing the stress response, would lead patients with autism to spend more proportionate time making eye contact, compared to placebo administration. Eye contact was measured using an ASL eyetracker and dynamic video stimuli of 16 novel faces at each of two drug condition visits. Eyetracker data was analyzed using the EyeNal and FixPlot programs by ASL.
Fourteen autism subjects with age/IQ/gender matched controls were tested in the verbal fluency study and the same fourteen autism subjects participated in the eyetracking study. Results indicate significant improvements in semantic fluency in autism subjects given propranolol, relative to the placebo condition. 2x2 ANOVA in the semantic fluency task revealed a trend for an interaction effect of drug and group as well as a significant main effect of drug, driven by the ASD group. In the eyetracking study, individuals with ASD and controls had similar amounts of eye-to-eye gaze under the placebo condition, which was unexpected. However, both groups improved significantly in the propranolol condition. 2x2 ANOVA in the eyetracker task revealed a trend for an interaction effect of drug and group as well as a main effect of drug.