Heresco‐Levy 2006.

Study characteristics
Methods	Double‐blind randomised controlled cross‐over trial
Participants	Diagnosis: DSM‐IV major depressive disorder; ≥ 4 weeks of treatment with an antidepressant drug; score ≥ 18 on HRSD‐21 N: 22 Age: M = 56.9 (SD = 12.4) Sex: 45% female Baseline depression severity: HRSD = 27.2 (SD = 5.2)
Interventions	6 weeks of treatment D‐cycloserine (N = 9) 250 mg orally per day Placebo (N= 13) in identical capsules to D‐cycloserine Concomitant treatment: y es, patients continued on existing psychotropic medications
Outcomes	HRSD HAMA Zung Self Rating Depression Scale PANSS UKU Side Effects Rating Scale
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: ''subjects were randomly allocated, without blocking, stratification or other restrictions'' no further details given
Allocation concealment (selection bias)	Unclear risk	No details given on allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: ''Clinical and research staff, patients and their families were unaware of and could not determine the study drug assignment by appearance or otherwise''
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: ''double blind'' no further details given
Incomplete outcome data (attrition bias) All outcomes	Low risk	Study reports dropouts
Selective reporting (reporting bias)	Unclear risk	Protocol not available, unclear if all prespecified outcomes reported in published report
Other bias	Low risk	No other potential sources of bias identified