Takamitsu 2015a.

Study characteristics
Methods	6‐week cross‐over trial of oxytocin versus placebo
Participants	Inclusion criteria: diagnosis of ASD male full‐scale IQ (480) aged 18–55 years Exclusion criteria: any history of allergic responses to oxytocin, seizures, traumatic brain injury with any known cognitive consequences, loss of consciousness for more than 5 min, and substance abuse or addiction. current instability of comorbid psychiatric symptoms and contraindications on MRI scanning Location/setting: outpatient clinic of The University of Tokyo Hospital, Japan Sample size: oxytocin‐placebo (10), placebo‐oxytocin (10) Number of withdrawals/dropouts: oxytocin‐placebo (1), placebo‐oxytocin (1) ‐ both due to self‐termination Gender: all participants were male Mean age: oxytocin‐placebo = 35.1, placebo‐oxytocin = 29.3 IQ: details not provided Baseline ABC‐I or other BoC: oxytocin‐placebo QoL 3.25 (0.65); placebo‐oxytocin 2.68 (0.82) Concomitant medications: details not provided History of previous medications: "moreover, a comparable effect size was also seen in psychotropic‐free participants after excluding one participant with continual medication of serotonin‐norepinephrine reuptake inhibitors for his recurrent major depression (d = 0.74)."
Interventions	Intervention (oxytocin) for 6 weeks: the participants received oxytocin (24 IU, Syntocinon‐Spray; Novartis) in the morning and afternoon over 6 consecutive weeks (i.e. 48 IU/day). Comparator (placebo) for 6 weeks: in the same way (24 IU placebo Syntocinon‐Spray; Novartis) in the morning and afternoon over 6 consecutive weeks (i.e. 48 IU/day).
Outcomes	Primary outcomes: none reported Secondary outcomes: QoL (WHO‐QoL) (WHO 1998)
Notes	Study start date: March 2012 Study end date: April 2013 Funding: "A part of this study is a result of the ‘Development of biomarker candidates for social behaviour’ project under the Strategic Research Program for Brain Sciences by the MEXT (K.K. and H.Y.) and the Centre of Innovation Program from Japan Science and Technology Agency (HY)". Conflicts of interest: "The authors declare no conflict of interests". Trial registry: UMIN000007122
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomised order
Allocation concealment (selection bias)	Unclear risk	Quote: "The manager completely covered the bottle labels to keep drug types unknown to all participants, their families, experimenters, clinicians and assessors including ADOS administrators and assessors"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Details not provided
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Details not provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants were accounted for and included in the analysis.
Selective reporting (reporting bias)	Low risk	Primary outcome measures reported per trial reg ‐ https://rctportal.niph.go.jp/en/detail?trial_id=UMIN000007122
Other bias	Low risk	No other sources of bias identified