More than 200 species of fungi have been reported with hallucinogenic properties belonging to more than 10 genera, both Basidiomycota (the majority) and Ascomycota. Psilocybe, Amanita muscaria and Claviceps purpurea are true hallucinogens. Of these, the more important are the psilocybes for their great global distribution, traditional ceremonial uses, and numerous potential clinical applications.
Psilocybe has more than 150 hallucinogenic species throughout the world which have long been used in ceremonial and traditional medicinal ways.
Amanita muscaria seems to be the oldest hallucinogenic mushroom used by humans, although the first hallucinogenic substance, LSD, was isolated from ergot, Claviceps purpurea.
Scientific interest in serotonergic psychedelics (e.g., psilocybin and LSD; 5-HT2A receptor agonists) has dramatically increased within the last decade. Clinical studies administering psychedelics with psychotherapy have shown preliminary evidence of profound efficacy in treating anxiety and depression, as well as addiction to tobacco and alcohol. Moreover, recent research has suggested that these compounds have potential efficacy against inflammatory diseases through novel mechanisms, with potential advantages over existing anti-inflammatory agents.
Psilocybin, the most clinically researched classic psychedelic has recently been tested for its safety and efficacy in a clinical population of treatment resistant depression. Psilocybin is the prodrug of psilocin (4-OH-dimethyltryptamine), a non-selective serotonin 2A receptor (5-HT2AR) agonist and classic ‘psychedelic’ drug. Both compounds occur naturally in the psilocybe genus of mushrooms and are structurally related to the endogenous neurotransmitter serotonin (5-OH-tryptamine, 5-HT). Psilocybin has an ancient and more recent history of medicinal use. Efficacy of psilocybin in the treatment of clinical depression has been demonstrated in the electrophysiologic and neuroimaging findings and in neuropsychological assessments.
Additionally, in recent years, there has been a growing awareness that the psychological, spiritual, and existential crises often encountered by patients with advanced cancer and their families need to be addressed more vigorously. From the late 1950s to the present, research has been conducted exploring the use of psilocybes to treat the existential anxiety, despair, and isolation often associated with advanced-stage cancer. Those studies have described critically ill individuals undergoing psychospiritual epiphanies, often with powerful and sustained improvement in mood and anxiety as well as diminished need for narcotic pain medication.
Hallucinogenic mushrooms constitute part of humanity’s ethnobotanical knowledge of substances of great medicinal and therapeutic importance cross-culturally and throughout history. Where used, these substances generally have been viewed as central sources of spiritual experience and religious participation, providing inspiration for the institutionalization of religious sentiments and activity.