Zachary Walsh

Zachary Walsh is a psychologist whose research focuses on the clinical and epidemiological study of psychedelics and related psychoactive substances. He has led and co‑authored multiple observational studies of psilocybin microdosing and classic psychedelic use, characterising motivations for use and associations with anxiety, depression and well‑being. His work interrogates psychological mechanisms such as spirituality and emotion processing that may mediate relationships between psychedelic use and mental‑health outcomes. In community and prospective samples he has examined broader population effects of hallucinogen use, including research suggesting potentially protective associations with intimate partner violence among men with histories of problematic substance use.

In addition to observational research, Walsh has contributed to clinical research efforts, including authorship on work that synthesises phase 2 randomized controlled trials of MDMA‑assisted psychotherapy to inform the design and rationale for phase 3 PTSD trials. His scholarship spans microdosing, psychedelic epidemiology, mechanism‑focused analyses, and translational clinical trial methodology, with a consistent emphasis on rigorous measurement, public‑health implications and harm‑reduction perspectives.