Table 2.

Clinical studies investigating cellular and molecular effects of serotonergic psychedelics.

References	Aim	Sample size (n)	Comparison	Psychedelic	Timing of measurement	Methods and measurements	Findings
Hutten et al. (50)	Effect of single, low dose LSD on circulating BDNF in healthy volunteers	8–10	Placebo	Once, 5, 10 or 20 μg LSD, p.o.	2, 4, 6 h	Serum BDNF	Serum BDNF + (5 μg, 20 μg): BDNF + (4 h, 5 μg). BDNF + (6 h, 20 μg). BDNF highest at 4 h (5 μg) and 6 h (10 μg, 20 μg)
Holze et al. (49)	Investigate subjective and autonomic effects and different doses of LSD in humans in a cross-over study.	16	Placebo, ketanserin	25, 50, 100, 200 μg LSD, 40 mg ketanserin, p.o. in 6 sessions, 10 days between	6, 12, 24 h	Questionnaires, serum BDNF	BDNF + at 6 h, anxiety and ego dissolution (200 μg dose). Non-significant stimulation BDNF (by low dose LSD, ketanserin)
Galvao-Coelho et al. (48)	Effects of ayahuasca on serum cortisol, BDNF and inflammatory markers and depressive symptoms.	28 TRD, 45 CG	Healthy volunteers, placebo	Once, 1 mL/kg aya*, p.o.	48 h	MADRS, serum BDNF	MADRS—(TRD), BDNF = (both groups)
de Almeida et al. (47)	Effect of a single ayahuasca treatment on BDNF in patients with TRD and healthy controls	28 TRD, 45 CG	Healthy volunteers, placebo	Once, 1 mL/kg aya (specific composition not reported), p.o.	48 h	MADRS, serum BDNF,	Serum BDNF + (control, TRD); MADRS—(TRD). Negative correlation serum BDNF levels and depressive symptoms

All studies were performed in adult male and females, timing of measurement is post-administration.

^*Ayahuasca composition: 0.36 mg/mL DMT, 1.86 mg/mL harmine, 0.24 mg/mL harmaline, 1.20 mg/mL tetrahydroharmine.

aya, ayahuasca; BDNF, Brain-derived neurotrophic factor; CG, control group; LSD, Lysergic acid diethylamide; MADRS, Montgomery-Åsberg Depression Rating Scale; p.o., Oral administration; TRD, treatment-resistant depression.