Psilocybin Microdosing on Cognition, Mood and Quality of Life

Effects of Psilocybin Microdosing on Cognition, Mood and Quality of Life: A Pilot Study

This study is being conducted to evaluate how of 30 days of intermittently microdosed psilocybin affects mood, cognition, subjective well-being and structural/functional MRI results compared to a placebo. Investigators hypothesize that compared to placebo, 30 days of intermittently microdosed psilocybin will produce observable changes in mood, cognition, subjective well-being and MRI, in the absence of psychedelic experiences.

Study Overview

• Status: Not yet recruiting
• Conditions: Psychedelic Microdosing Effects on Mood, Cognition, Subjective Well-being and MRI
• Intervention / Treatment: Drug: Psliocybin; Drug: Placebo

Detailed Description

This study is being conducted to evaluate the effects of 30 days of intermittently microdosed psilocybin in a parallel arm double-blind manner on mood, cognition, subjective well-being and structural/functional MRI compared to placebo, using validated psychological assessments and cognitive tests. Investigators hypothesize that compared to placebo, 30 days of intermittently microdosed psilocybin will produce observable changes in mood, cognition, subjective well-being and MRI, in the absence of psychedelic experiences.

Demonstrating significant results in a population of healthy psychedelic non-users will establish a strong precedent for studying the effects of microdosing psychedelics in patient populations, such as those with treatment-resistant depression. Showing that microdosing minimizes risk of adverse outcomes with psychedelic treatment while maintaining beneficial effects would provide useful information relevant to clinical research in psychedelic-assisted psychotherapy. In addition to investigating claims that microdosing psychedelics may improve cognition and mood, this study also aims to test the hypothesis that these effects including those measurable at a brain level may persist beyond the course of the 30 days of the study. There are few to no studies that assessed the longevity of psychedelic effects on the majority of the above measures, so the proposed study may further establish the longer-term benefits of microdosing. The use of structural and functional magnetic resonance imaging (fMRI) will elucidate the mechanisms by which microdosing may be exerting its effects on mood and cognition. Because this is a relatively understudied area, information gleaned from this study will provide service in informing the field in general.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Early Phase 1

Contacts and Locations

• Study Contact: Name: Godfrey Pearlson, MD; Phone Number: 860-545-7757; Email: godfrey.pearlson@hhchealth.org

Study Locations

• United States
  • Connecticut
    • Hartford, Connecticut, United States, 06106
      • Olin Neuropsychiatry Research Center
      • Contact: Diana King; Phone Number: 860-545-7563; Email: diana.king@hhchealth.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• No history of psychedelic use
• Able to read, speak, and understand English
• Able and willing to provide written informed consent, and willing to commit to study protocol
• Women of childbearing potential must be on a highly effective birth control method

Exclusion Criteria:

• Positive screen for recreational drugs or alcohol on test day will result in rescheduling the appointment
• Current mood, developmental, or psychotic disorders (e.g., schizophrenia, affective disorders) per DSM-V
• Current or past alcohol or substance use disorder per DSM-V
• IQ <70 on the Weschler Abbreviated Scale of Intelligence
• Serious medical, neuro-ophthalmological, or neurological illness (e.g., cancer, seizure disorders, encephalopathy)
• Current pregnancy, breastfeeding, or ineffective birth control methods
• History of head trauma with loss of consciousness lasting >30 minutes or concussion in last 30 days
• Any medical/neurological condition that could compromise neurocognitive performance (e.g., epilepsy, multiple sclerosis, fetal alcohol syndrome)
• Anyone deemed unsafe to study personnel for any reason; e.g., suicidal ideation
• Focal brain lesion seen on structural MRI
• MRI contraindications (e.g., implanted metallic object, severe claustrophobia)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Psychedelic group; An imperceptible dose of psilocybin in capsules will be administered to subjects three times weekly for four weeks. Assessments will be conducted once weekly. After 30 days of a steady dose of psilocybin, subjects will be re-assessed with baseline measures.	Drug: Psliocybin; 2.0mg powdered psilocybin derived from Psilocybe cubensis mushrooms, in capsules, provided three times weekly for four weeks
Placebo Comparator: Placebo group; An dose of placebo in capsules, identical to the active, will be administered to subjects three times weekly for four weeks. Assessments will be conducted once weekly. After 30 days of a steady dose of psilocybin, subjects will be re-assessed with baseline measures.	Drug: Placebo; 0mg matching capsules, provided three times weekly for four weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The Complex Working Memory Span (CWMS) Task- fMRI measure	CWMS Task assesses immediate plus delayed recall and working memory by assessing working memory capacity by presenting a list of stimuli to be recalled while simultaneously performing a secondary task. This task uses a fully crossed design which includes both same-domain CWMS conditions (e.g. verbal storage combined with verbal processing) as well as cross-domain CWMS conditions (e.g., verbal storage combined with spatial processing). BOLD signal Infrontal lobe.	From enrollment to end of treatment at 8 weeks.
NEO-Five-Factor-Inventory (NEO-FFI)	The NEO-FFI is a self-description questionnaire with 60 items for the measurement of the "big five": neuroticism, extraversion, openness, agreeableness, and consciousness. It uses a 5-point Likert scale ranging from "completely disagree" to "fully agree.	From enrollment to end of treatment at 8 weeks.
Beck Depression Inventory	This scale has a total of 21 items. Each item is scored from 0-3 points, and the total score ranges from 0-63 points. The higher the score, the higher the degree of depression.	From enrollment to end of treatment at 8 weeks.
Beck Anxiety Inventory	Beck Anxiety Inventory is a 21-item self-reported questionnaire which measures the existenceand severity of symptoms of anxiety. Each of the 21 items on BAI tool represents an anxiety symptom. A total score of 0 - 7 is interpreted as a "Minimal" level of anxiety; 8 - 15 as "Mild"; 16 - 25 as "Moderate", and 26 - 63 as "Severe".	From enrollment to end of treatment at 8 weeks.
Harvard Flourishing Measure	12 questions, rating from 0 to 10 per question, sum score to calculate the 'flourish measure' will be used.	From enrollment to end of treatment at 8 weeks.
NIH Toolbox Cognitive Battery	Cognitive function will be assessed using the NIH Toolbox Cognition Battery, administered on an iPad.	From enrollment to end of treatment at 8 weeks.
Switching Stroop Test	Stroop task measures response inhibition or response interference control. Participants will be shown a series of word colors that are either congruent or incongruent with the color of the word itself. The participant will be asked to respond to the color of the word and not the word itself. Responses are made with the keyboard. The incongruent condition is the more difficult condition of the two. Reaction time is recorded and a cost score is calculated, with shorter cost scores indicating better performance.	From enrollment to end of treatment at 8 weeks.
Flanker Inhibitory Control and Attention Test	This test is designed to evaluate an individual's ability to concentrate their attention while inhibiting automatic response tendencies that could potentially hinder goal achievement. This is the percent correct outcome from this assessment.	From enrollment to end of treatment at 8 weeks.
Face Name Associated Memory Exam	The score ranges from 0 to 130, with a higher score indicating better speed of processing.	From enrollment to end of treatment at 8 weeks.
9-hole pegboard dexterity test	The Nine-Hole Peg Test (9HPT) is used to measure finger dexterity in patients with various neurological diagnoses. Time to complete the test as quickly as possible	From enrollment to end of treatment at 8 weeks.
NIH Toolbox Cognitive Battery	The Nine-Hole Peg Test (9HPT) is used to measure finger dexterity in patients with various neurological diagnoses. Time to complete the test as quickly as possible	From enrollment to end of treatment at 8 weeks.
Neurite Orientation Dispersion and Density Imaging (NODDI)	Assessing synaptic plasticity in MRI	From enrollment to end of treatment at 8 weeks.
Ecological Momentary Assessments (EMAs) w/ MindLamp	Once-daily questions (EMAs) about mood and sleep will be sent via the MindLamp smartphone app.	From enrollment to end of treatment at 8 weeks.
Penn Conditional Exclusion Test	Neurocognition measure of reasoning & problem solving in PennCNB. Scores will be transformed into z-scores. The key score will assess perseverative errors. Lowest score = 0, no max score. A higher score is correlated with worse performance, i.e. more perseverative errors.	From enrollment to end of treatment at 8 weeks.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Complex Working Memory Span task	Measures ability to juggle holding information (storage) and doing something with it (processing) at the same time. Percent accuracy will be reported.	From enrollment to end of treatment at 8 weeks.
fMRI	Mean BOLD signal	From enrollment to end of treatment at 8 weeks.

Collaborators and Investigators

• Sponsor: Yale University
• Collaborators: Hartford HealthCare
• Investigators: Principal Investigator: Godfrey Pearlson, MD, Yale University

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): April 1, 2028
• Study Completion (Estimated): April 1, 2028

Study Registration Dates

• First Submitted: February 26, 2026
• First Submitted That Met QC Criteria: February 26, 2026
• First Posted (Actual): March 4, 2026

Study Record Updates

• Last Update Posted (Actual): March 31, 2026
• Last Update Submitted That Met QC Criteria: March 25, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: MRI; fMRI; Psilocybin; Psychedelics; Microdosing
• Other Study ID Numbers: HHC-2025-0200

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No