NCT01337687.

Study characteristics
Methods	6‐week parallel trial of oxytocin versus placebo
Participants	Inclusion criteria: male or female 18‐55 years meet DSM‐4, ADOS, and ADI‐R standards for ASD or Asperger's Syndrome have a high, normal or near normal IQ speak and understand English fluently Exclusion criteria: born prior to 35 weeks' gestational age any psychiatric diagnosis apart from autism any neurological disorders known MRI/structural lesion of the brain pregnant taking psychoactive medication evidence or history of a significant haematological, endocrine, cardiovascular, respiratory, renal, hepatic or gastrointestinal disease planning to initiate or change medications during the trial unable to tolerate blood sampling Location/setting: Montefiore Medical Center, USA Mean IQ: not reported Mean age: 33.2 years Gender: 16 male, 3 female Sample size: 19 in total Reasons for dropouts/withdrawals: none reported Baseline ABC‐I or other BoC scale: not reported Concomitant medications: details not provided Previous medications: details not provided
Interventions	Intervention (oxytocin) for 6 weeks: administered intranasally twice a day via 1 x 12 unit puff to each nostril, totalling 48 IU a day Comparator (saline) for 6 weeks: administered intranasally twice a day via 1 puff per nostril, totalling 48 IU a day
Outcomes	Primary outcomes: AEs Secondary outcomes: none reported Timing of outcome assessments: baseline and 6 weeks (endpoint)
Notes	Study start date: April 2011 Study end date: February 2020 Funding: details not provided Conflicts of interest: details not provided
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Details not provided
Allocation concealment (selection bias)	Unclear risk	Details not provided
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Only details provided were on the trial registry, "Masking: quadruple (participant, care provider, investigator, outcomes assessor)"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Only details provided were on the trial registry, "Masking: quadruple (participant, care provider, investigator, outcomes assessor)"
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropout reported
Selective reporting (reporting bias)	Unclear risk	No peer‐reviewed paper
Other bias	Low risk	No other sources of bias identified