Table 2 Recent depletion studies comparing acute tryptophan depletion drink with amino acid balance drink (sham drink) - characteristics and results.
From: The serotonin theory of depression: a systematic umbrella review of the evidence
Study | Randomised controlled trial design | Participants: Healthy volunteers (HV) or people with depression* | Medication status | Summary effect (95% CI), p |
|---|---|---|---|---|
Frey & McCabe, 2020 | Parallel group, double blind | 46 HV | No psychotropic medication for at least 3 months | No effect |
Bar et al., 2020 | Crossover trial, double blind | 30 HV | Not specified | No effect |
Deza-Araujo et al., 2018 | Crossover trial, double blind | 85 HV | Not specified | No effect |
Martin et al., 2017 | Crossover trial, double blind | 15 HV | No history of neurological or psychiatric disorders | No effect |
Eisner et al., 2016 | Crossover trial, double blind | 64 HV | No history of neurological or psychiatric disorders | No effect |
Trotter et al., 2016 | Parallel group, double blind | 30 HV | Not specified | No effect |
Hogenelst 2016 | Crossover trial, double blind | 40 HV with or without a family history of MDD | ‘No use of psychotropics’ | No effect |
Weinstein et al., 2015 | Crossover trial, double blind | 15 people with depression | Treated with sertraline for 12 weeks prior to study | No effect |
Moreno et al., 2015 | Crossover trial, double blind | 64 people with personal and family history of MDD; in remission | No ‘psychotropic medication’ for at least 3 months prior to test | A significant main effect of test condition (χ 2 = 5.14, d.f. = 1, p = 0.023) mainly due to improvement of HDRS scores following sham drink |
Hembold et al., 2013 | Crossover trial, double blind | 18 HV | Not specified | No effect |
