Oxytocin and Cognitive Control in Adult ADHD

This is a randomized, double-blind, placebo-controlled crossover study of single-dose intranasal oxytocin (24 IU) in 18-55 year-old men with attention deficit/hyperactivity disorder (ADHD). Following a screening visit to determine eligibility, participants will return for two main study visits. During the main study visits, study participants will receive either oxytocin (Syntocinon® nasal spray, Victoria Pharmacy, Zürich, Switzerland) or placebo (inactive ingredients of Syntocinon® nasal spray, Victoria Pharmacy), followed by assessments of cognitive control over attention and behavior. Twenty-four participants will be randomized 1:1 to one of two drug orders, i.e., oxytocin - placebo or placebo - oxytocin. In an additional neuroimaging substudy, a subset of participants will undergo task-based and resting-state functional magnetic resonance imaging (fMRI) following oxytocin/placebo administration to investigate the effects of oxytocin on fMRI activation and functional connectivity within the cognitive control network.

Attention, Attention deficit/hyperactivity disorder, Cognitive control, Executive control, Executive functions, Impulse control, Impulsivity, Oxytocin

Single-dose intranasal oxytocin (24 IU; Syntocinon® nasal spray, Victoria Pharmacy, Zürich, Switzerland)

Single-dose intranasal placebo (inactive ingredients of Syntocinon® nasal spray, Victoria Pharmacy, Zürich, Switzerland)

Mean difference in performance on the stop-signal task between the oxytocin and placebo visits (e.g., stop-signal reaction time)

Mean difference in performance on the AX-CPT between the oxytocin and placebo visits (AY and BX responses)

Mean difference in performance on the category switch task between the oxytocin and placebo visits (switch costs and target congruency effect)

Mean difference in performance on the global/local task between the oxytocin and placebo visits (global precedence effect)

Mean difference in performance on the Simon task between the oxytocin and placebo visits (Simon effect and Garner effect)

Inclusion criteria: Male 18-55 years Diagnosis of attention deficit/hyperactivity disorder Exclusion criteria: History of cardiovascular disease (e.g., hypertrophic cardiomyopathy, valvular heart disease, coronary heart disease, or coronary artery spasms) History of diabetes mellitus Untreated thyroid disease Hematocrit below the normal range Tobacco use Any other significant illness or condition that the investigator determines could interfere with study participation or safety or put the subject at any unnecessary risk Excluded at the investigator's clinical judgement of ADHD symptom severity