Case Report: Repeated low doses of psilocybin reduce perceived symptom severity but fail to restore cognitive flexibility in a case of severe obsessive-compulsive disorder: an observational case study of identical twins.
Sivert Drange, Jacob Cohen, Sys Stybe Johansen, Ben Dunkley, Mikael Palner
Frontiers in Psychiatry 2026 DOI: 10.3389/fpsyt.2026.1819962 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Case study Longitudinal Case report Peer reviewed |
|---|---|
| Sample size | 2 |
| Population | Identical twins discordant for obsessive-compulsive disorder |
| Intervention | Psilocybin-containing mushrooms |
| Dose | 1-5 mg of psilocybin every 3rd day |
| Topics | Psilocybin |
| Keywords | Case report Case study Cognitive flexibility Low doses Obsessive-compulsive disorder Twins |
| Citations | 1 |
| Key findings | Low-dose psilocybin reduced OCD symptoms and improved well-being in the affected twin, but cognitive flexibility deficits persisted compared to the unaffected twin. |
Abstract
Obsessive-Compulsive Disorder (OCD) can present significant challenges to individuals mental health, characterized by intrusive thoughts and repetitive maladaptive behaviors. Recent research into alternative treatments has highlighted psychedelics, notably psilocybin, for their potential therapeutic benefits in various psychiatric disorders, including OCD. This case study evaluated the impact of self-administered, low-doses of psilocybin, commonly referred to as microdosing, on symptom reduction and cognitive flexibility in OCD, with a focus on identical twins discordant for the condition. The study documents the experiences of one twin diagnosed with OCD who began a regimen of low-doses of psilocybin containing mushrooms, while the other twin, unaffected by OCD, served as a comparison. Case X was diagnosed with OCD by a general practitioner in the Danish healthcare system. Following years of severe OCD, case X began a self-medicated regimen consisting of psilocybin containing mushrooms, corresponding to 1-5 mg of psilocybin, every 3rd day. The other twin, case Y, who remained unaffected by OCD, and did not take psilocybin containing mushrooms. Cognitive flexibility was evaluated in both cases using a set-shift task. The affected twin reported a notable reduction in OCD symptoms, along with improvements in emotional regulation and overall well-being. However, despite these symptomatic improvements, deficits in cognitive flexibility remained present compared to the unaffected twin. This case study underscores the potential of low-doses of psilocybin as a promising avenue for mitigating symptoms of OCD. Nevertheless, the observed disparity in cognitive flexibility highlights the nuanced nature of OCD pathology, suggesting that while low-doses of psilocybin may alleviate certain symptoms, it may not fully address underlying cognitive impairments. Further research employing larger sample sizes and rigorous longitudinal designs is imperative to elucidate the mechanisms underlying the therapeutic effects of psilocybin low-doses in OCD, offering insights into its broader applicability as a treatment modality.
Comparable studies
Other case reports and case series on psilocybin, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Psilocybin Mushroom (Psilocybe semilanceata) Intoxication with Myocardial Infarction 18-year-old man | 1998 | Case study | n = 1 |
| Relief from intractable phantom pain by combining psilocybin and mirror visual-feedback (MVF) Person with leg amputation and phantom-limb pain | 2018 | Case study | n = 1 |
| Hallucinogen persisting perception disorder after psilocybin consumption: a case study 18-year-old man with HPPD after mixed psilocybin and cannabis intoxication | 2005 | Case study | n = 1 |
| Microdosing psilocybin for chronic pain: a case series Individuals with chronic neuropathic pain | 2022 | Case series | n = 3 |
| Psilocybin and Obsessive Compulsive Disorder Individual with Obsessive Compulsive Disorder | 2014 | Case study | n = 1 |
Citations in the library
Cited by 2
Cites 29
- Safety, Tolerability, and Efficacy of Psilocybin in 9 Patients With Obsessive-Compulsive Disorder The Journal of Clinical Psychiatry November 15, 2006
- Psilocybin therapy increases cognitive and neural flexibility in patients with major depressive disorder. Translational Psychiatry November 8, 2021
- Motives and Side-Effects of Microdosing With Psychedelics Among Users The International Journal of Neuropsychopharmacology May 30, 2019
- Microdosing with psilocybin mushrooms: a double-blind placebo-controlled study Translational Psychiatry August 2, 2022
- The therapeutic potential of microdosing psychedelics in depression Therapeutic Advances in Psychopharmacology 2020
and 24 more in the library