Postpartum depression: A role for psychedelics?

Jairaj and colleagues frame postpartum depression (PPD) as a common and consequential disorder that overlaps with major depressive disorder (MDD) but also shows distinct features, notably a disruption of the mother–infant relationship and a core experience of maternal 'disconnection'. They note that conventional treatments for PPD have limited evidence of efficacy and emerging treatment resistance; brexanolone is the only medication developed specifically for PPD but is costly, requires prolonged inpatient administration, and is not widely generalisable. Given these gaps, the authors argue for exploring treatments with novel mechanisms. This narrative review sets out to outline the therapeutic rationale for serotonergic psychedelics, principally psilocybin, in the treatment of PPD and to discuss safety and pragmatic considerations for use in the postpartum period. The review emphasises potential benefits for maternal mood and maternal sensitivity towards the infant, and calls for examination of safety and feasibility in breastfeeding women as a precursor to pilot clinical trials.

This paper is a narrative review rather than a systematic review or meta-analysis. Jairaj and colleagues examined the available clinical and preclinical literature on PPD, the clinical trial evidence for classic serotonergic psychedelics (mainly psilocybin) in depression and related conditions, and the limited pharmacokinetic and safety data relevant to postpartum and breastfeeding contexts. The extracted text does not report a structured search strategy, databases searched, inclusion criteria, or risk-of-bias assessment, so the review should be understood as a targeted narrative synthesis of existing evidence rather than a comprehensive systematic appraisal. Where trial data are discussed, the authors summarise key study designs and outcomes from early-phase open-label studies, waiting-list controlled trials, and Phase II randomised controlled trials in MDD, and they integrate pharmacokinetic considerations (for example, timing of peak plasma concentration and elimination half-life of psilocin) insofar as these relate to potential breastmilk transfer and infant exposure. Safety and ethical guidance on inclusion of breastfeeding women in clinical research is also considered to inform proposed pragmatic approaches for future trials in PPD.

Overview of psychedelic research: Early mid-20th-century research into classic psychedelics was extensive but methodologically limited, and regulatory restrictions halted clinical use for decades. Contemporary trials resumed after 2000. A pooled analysis of eight double-blind placebo-controlled experimental studies (1999–2008) in 110 healthy volunteers who received oral psilocybin (45–315 µg/kg) reported acute dysphoric or anxious episodes in a small proportion of participants which were managed with interpersonal support; follow-up suggested no subsequent substance misuse, prolonged psychosis or long-term functional impairment. A 2019 large randomised double-blind study of cognitive safety in healthy volunteers reported no negative impact on cognitive scales and no serious adverse events up to 12 weeks after dosing. Psilocybin trials in depression: Early open-label and single-centre studies have reported rapid and sometimes large reductions in depressive symptoms. An open-label pilot of psilocybin-assisted psychotherapy in 12 patients with treatment-resistant depression used preparatory sessions followed by 10 mg and 25 mg doses given 7 days apart; one week after dosing 67% of participants had achieved complete remission, with depression scores dropping from 21.4 to 7.4 and a Hedges' g effect size of 3.1. At 3 months, 58% maintained response and 42% remained in remission; effects persisted to 6 months with a smaller effect size. A randomised waiting-list controlled trial in 27 participants reported rapid symptom reduction (mean score 16.7 to 6.3 on day 1 after the first dose) and an overall clinically significant response in 67% at week 1 rising to 71% at week 4, with a Cohen's d of 2.2 at four weeks. More rigorous comparative evidence is limited. A Phase II double-blind RCT compared two 25 mg doses of psilocybin to escitalopram in 59 participants with moderate-to-severe MDD; both arms received psychological support. Change in QIDS-SR-16 from baseline to week 6 was -8.0 ± 1.0 for psilocybin and -6.0 ± 1.0 for escitalopram, giving a between-group difference of 2 points (95% CI: -5.0 to 0.9), which did not reach statistical significance for the primary outcome. Secondary outcome measures tended to favour psilocybin but were not corrected for multiple comparisons. COMPASS Pathways reported (pre-peer review) results from a Phase IIb multi-centre trial in 233 participants with treatment-resistant depression, where a single 25 mg dose produced rapid reductions in symptom severity and nearly 25% sustained response at 12 weeks; most treatment-emergent adverse events occurred and resolved on the day of administration, and reports of suicidal ideation/behaviour occurred in non-responders. Psychedelics and postpartum-specific data: There are no animal or human studies specifically examining psychedelic safety in the postpartum period or in breastfeeding. Pharmacokinetic data relevant to breastmilk exposure are limited but informative: oral psilocybin is metabolised to psilocin, which peaks at about 105 ± 37 minutes and has an elimination half-life of approximately 3 hours; one study found psilocin undetectable in urine after 24 hours, and the authors note that almost all psilocin would be eliminated by 48 hours after dosing. Psilocybin and psilocin bind to human serum albumin, which may reduce passive diffusion into milk, and psilocin is acidic (pH ~5.2), a property that tends to reduce transfer into breastmilk; conversely, its low molecular weight and lipid solubility could favour transfer. Infant risk from breastmilk exposure is age-dependent in general pharmacology data cited: about 78% of reported drug-related adverse effects in breastfed infants occur when infants are under 2 months old, while only 4% occur in infants older than 6 months. Therapeutic rationale and mechanism-related findings: The authors collate qualitative and mechanistic observations from psychedelic trials that are pertinent to PPD. Psychedelic experiences commonly include mystical-type phenomena and increased feelings of connectedness, self-awareness, self-compassion and acceptance; such changes have been associated with enduring improvements in mood in psilocybin trials. Preclinical and human data indicate serotonergic receptor activity (notably 5-HT2A agonism) and changes in neural network connectivity (for example, modulation of default mode network and amygdala activity), and LSD has been associated with transient increases in oxytocin in healthy participants. Given evidence linking maternal oxytocin to sensitivity in mother–infant interactions, the authors suggest a plausible pathway by which psychedelics might improve maternal sensitivity and the mother–infant relationship when combined with psychological support and integration.

Jairaj and colleagues interpret the assembled evidence as indicating that psilocybin-assisted therapy could be a promising avenue to address core features of PPD, particularly the maternal experience of 'disconnection' from self and infant, while also improving mood. They emphasise that psilocybin in therapeutic contexts appears to promote openness, acceptance and connectedness, and that psychedelic-assisted therapy provides a model of preparation, supervised dosing and integration that may both maximise benefit and manage acute adverse experiences. The authors stress the paucity of postpartum-specific safety data: classic psychedelics have been excluded from trials in pregnant or breastfeeding women, and no studies directly address breastmilk transfer or infant effects. Nevertheless, they note pharmacokinetic indicators (rapid elimination of psilocin, albumin binding, acidity) that could be used to devise pragmatic safeguards such as advising abstention from breastfeeding for 48 hours post-dose and limiting initial trials to women beyond 6 months postpartum to reduce infant exposure risk. Jairaj and colleagues also point to evolving ethical guidance supporting inclusion of breastfeeding women in research where infant safety is appropriately considered and monitored, and they argue this supports designing carefully controlled pilot studies rather than blanket exclusion. Key limitations acknowledged by the authors include reliance on small, single-centre phase 2 trials for much of the psilocybin efficacy signal, lack of replication in large multi-centre RCTs, and absence of empirical data on psychedelic safety in the postpartum and breastfeeding context. They therefore propose a cautious next step: a pilot study to evaluate safety and preliminary efficacy of psilocybin-assisted therapy in PPD with appropriate precautionary and monitoring measures, which could inform subsequent larger trials and decisions about inclusion criteria and breastfeeding management.

The authors conclude that psychedelic-assisted therapy, particularly with psilocybin, has the potential to address a central feature of PPD — maternal loss of connection with self and infant — and to promote enduring improvements in acceptance and maternal role gratification that could benefit the mother–infant dyad. Given demonstrated safety of psilocybin in adult and MDD populations when administered in therapeutic settings, they argue it is reasonable to examine psilocybin safety in the postpartum period via a pilot study that would inform future research in PPD.