Deepak Cyril Dsouza, MBBS, MD
Vikram Sodhi ’92 Professor of PsychiatryCards
Appointments
Additional Titles
Director Schizophrenia Neuropharmacology Research Group at Yale (SNRGY)
Director, Neurobiological Studies Unit, VACHS
Director, VA-CMHC Schizophrenia Research Clinic
Director, Yale Center for the Science of Cannabis and Cannabinoids
Chair, Research and Development Committee, VA Connecticut Healthcare System
Contact Info
Psychiatry
950 Campbell Avenue
West Haven, CT 06516
United States
Appointments
Additional Titles
Director Schizophrenia Neuropharmacology Research Group at Yale (SNRGY)
Director, Neurobiological Studies Unit, VACHS
Director, VA-CMHC Schizophrenia Research Clinic
Director, Yale Center for the Science of Cannabis and Cannabinoids
Chair, Research and Development Committee, VA Connecticut Healthcare System
Contact Info
Psychiatry
950 Campbell Avenue
West Haven, CT 06516
United States
Appointments
Additional Titles
Director Schizophrenia Neuropharmacology Research Group at Yale (SNRGY)
Director, Neurobiological Studies Unit, VACHS
Director, VA-CMHC Schizophrenia Research Clinic
Director, Yale Center for the Science of Cannabis and Cannabinoids
Chair, Research and Development Committee, VA Connecticut Healthcare System
Contact Info
Psychiatry
950 Campbell Avenue
West Haven, CT 06516
United States
About
Copy Link
Titles
Vikram Sodhi ’92 Professor of Psychiatry
Director Schizophrenia Neuropharmacology Research Group at Yale (SNRGY); Director, Neurobiological Studies Unit, VACHS; Director, VA-CMHC Schizophrenia Research Clinic; Director, Yale Center for the Science of Cannabis and Cannabinoids
Positions outside Yale
Chair, Research and Development Committee, VA Connecticut Healthcare System
Biography
Deepak Cyril D’Souza, MD is a Professor of Psychiatry, Yale University School of Medicine and a staff psychiatrist at VA Connecticut Healthcare System (VACHS). He received his medical degree from John’s National Academy of Health Sciences, Bangalore, India in 1986 and completed his psychiatric residency at State University of New York Downstate in 1992 followed by a postdoctoral fellowship in Psychopharmacology and Neurosciences at Yale University School of Medicine. He then joined the faculty in the Dept. of Psychiatry at Yale and VA Connecticut Healthcare System. He is an active clinician, teacher and researcher, 30 years of experience.
Clinical Administration: He directs the Neuropsychiatry Program at VA Connecticut Healthcare System, the clinical service that cares for veterans with serious mental illnesses including psychotic disorders, mood disorders and personality disorders. He also chairs the Research and Development Committee at VA Connecticut Healthcare System.
Research Administration: He directs the Neurobiological Studies Unit where experimental psychopharmacological studies are conducted. He serves as the Chair of the Research and Development Committee of VA Connecticut Healthcare System.
Education: He is actively involved in teaching residents. In recognition of his contributions as a teacher, he received the Yale Psychiatry resident’s teaching award in 2008. He also directs the VA Schizophrenia Research Fellowship program the training ground for a number of current researchers. He is a mentor for a number of junior faculty who have career awards.
Pathophysiological Research: He directs the Schizophrenia Neuropharmacology Research Group at Yale (SNRGY). Over the last 3 decades, he has employed three approaches to his research. He has conducted experimental psychopharmacological studies with ketamine, amphetamine, THC, nicotine, salvinorin A in healthy human volunteers and patients to evaluate the contributions of various neurotransmitter systems to the pathophysiology of psychosis, cognitive deficits, and reward dysfunction. He also uses in vivo neuroreceptor imaging to study schizophrenia and cannabis use disorder with ligands that bind to synaptic vesicles, muscarinic receptors, CB1 receptors, etc. He is also involved in a consortium to collect fluid biomarkers in schizophrenia.
Treatment Research: In parallel to these studies of pathophysiology, he has conducted phase 1 - 4 clinical trials to develop new treatments schizophrenia, mood disorders and cannabis use disorder. More recently he has been investigating the therapeutic potential of psychedelic compounds (psilocybin, dimethyltryptamine) in the treatment of neuropsychiatric conditions including depression and migraine. His research is funded by the U.S. National Institute of Drug Abuse (NIDA), the National Institute of Mental Health (NIMH), the National Institute of Alcoholism and Alcohol Abuse (NIAAA), VA R&D and several foundations.
His work has been published in the highest impact Psychiatry journals including Molecular Psychiatry, Lancet Psychiatry, Biological Psychiatry, American Journal of Psychiatry and Neuropsychopharmacology (https://scholar.google.com/citations?user=qDmD8DsAAAAJ&hl=en). He is a principal editor of the journal Psychopharmacology.
He is involved in public outreach – he serves on the Physicians Advisory Board for Connecticut’s Medical Marijuana Program. He is recognized as a leading expert on the relationship between cannabinoids and psychosis, and has been involved educating the general public about the relationship between cannabis and psychosis.
Appointments
Psychiatry
ProfessorPrimary
Other Departments & Organizations
- Abraham Ribicoff Research Facilities
- All Institutions
- Center for Brain & Mind Health
- MR Core
- Neuroscience Research Training Program (NRTP)
- Psychiatry
- Schizophrenia Research Clinic
- Yale Center for the Science of Cannabis and Cannabinoids
- Yale Global Mental Health Program
- Yale Ventures
Education & Training
- MD
- SUNY at Brooklyn (1992)
- MBBS
- St. John's Medical College (1986)
Research
Copy Link
Overview
Medical Research Interests
ORCID
0000-0003-3141-1462
Research at a Glance
Yale Co-Authors
Publications Timeline
Research Interests
John Krystal, MD
Edward Belk Perry Jr, MD, MHS
Ralitza Gueorguieva, PhD
Ashley Schnakenberg Martin, PhD
Ismene Petrakis, MD
Nabeel Nabulsi, PhD
Mental Disorders
Publications
2026
Cannabis and Mental Health
Kansagara D, Terry G, Ayers C, D’Souza D. Cannabis and Mental Health. JAMA Internal Medicine 2026, 186 PMID: 41801216, DOI: 10.1001/jamainternmed.2025.8215.Peer-Reviewed Original ResearchAltmetricConceptsCannabis use disorderMental health conditionsCannabis useMental health symptomsBenefits of cannabisUse disorderHealth symptomsSymptoms of posttraumatic stress disorderRisk of cannabis use disorderPsychotic spectrum disordersPast-year cannabis usePosttraumatic stress disorderCannabis constituent cannabidiolAttention-deficit/hyperactivity disorderRisk of psychosisSubstance use disordersTreatment of mental health conditionsYoung adultsAdverse mental health effectsMental health effectsMania symptomsAnxiety disordersPsychotic symptomsPsychotic disordersStress disorderChanges in cannabis use following legalization: Effects in first-episode psychosis
Purushothaman D, Tayfur S, Song Z, Li F, Corbera S, Sykes L, Riley S, Terashima J, D'Souza D, Tek C, Srihari V. Changes in cannabis use following legalization: Effects in first-episode psychosis. Schizophrenia Research 2026, 290: 86-87. PMID: 41671766, DOI: 10.1016/j.schres.2026.02.001.Peer-Reviewed Original Research
2025
Cannabis Use in Older Individuals May Be an Important and Under-Recognized Risk Factor for Motor Vehicle Crashes
Pearlson G, D’Souza D, Marottoli R, Stevens M. Cannabis Use in Older Individuals May Be an Important and Under-Recognized Risk Factor for Motor Vehicle Crashes. Cannabis And Cannabinoid Research 2025, 11: 5-10. PMID: 41467908, DOI: 10.1177/25785125251410814.Peer-Reviewed Original ResearchMeSH Keywords and ConceptsConceptsBrain endocannabinoid systemMotor vehicle crashesDriving abilityAbilities of older adultsMild cognitive impairmentCannabis effectsNeurocognitive abilitiesTHC metabolismCannabis useEndocannabinoid systemAge-related changesNeurocognitive functionVehicle crashesCannabisCognitive impairmentAcute useRate of motor vehicle crashesOlder adultsEarly dementiaPublic health messagesUnder-recognized risk factorPopulation of individualsRisk of involvementAge-related factorsOlder DriversComparing single‐ and repeat‐dose psilocybin with active placebo for migraine prevention in an exploratory randomized controlled clinical trial
Schindler E, Gottschalk C, Pittman B, D'Souza D. Comparing single‐ and repeat‐dose psilocybin with active placebo for migraine prevention in an exploratory randomized controlled clinical trial. Headache The Journal Of Head And Face Pain 2025 PMID: 41459830, DOI: 10.1111/head.70024.Peer-Reviewed Original ResearchAltmetricConceptsDose of psilocybinDrug administration sessionsEffects of psilocybinAcute subjective effectsAdministration sessionsSubjective effects of psilocybinMigraine frequencyAcute psychedelic effectsSafety of psilocybinBlind integrationAcute effectsWeekly migraine daysDrug sessionsPsilocybin treatmentPsychedelic effectsTherapeutic effectActive placeboConfidence ratingsParallel-group studyPsilocybinPrevention of migraineRandomized controlled clinical trialPulse dose regimenPlacebo effectDrug effectsAge-Related Acute Subjective, Behavioral, Cognitive and Cardiovascular Effects of Tetrahydrocannabinol
D’Souza D. Age-Related Acute Subjective, Behavioral, Cognitive and Cardiovascular Effects of Tetrahydrocannabinol. Innovation In Aging 2025, 9: igaf122.1970. PMCID: PMC12761418, DOI: 10.1093/geroni/igaf122.1970.Peer-Reviewed Original ResearchConceptsAcute effects of cannabinoidsCannabis-related problemsEffects of THCEffects of tetrahydrocannabinolPharmacokinetics of THCEffects of cannabinoidsYoung adultsAcute effectsRisks of cannabisOlder adultsLegalization of cannabisAge-related differencesPlacebo-controlled crossover studyMedical cannabis useOlder individualsAnxiogenic effectsCannabis effectsCannabis useEndocannabinoid systemImmediate recallAge-related changesPsychomotor functionCardiovascular effectsCognitive functionControlled double-blindCannabis, Aging and Cognition: An Urgent Need for Research
D’Souza D, Gupta P, Martin A, Stevens M, Pearlson G. Cannabis, Aging and Cognition: An Urgent Need for Research. Cannabis And Cannabinoid Research 2025, 11: 1-4. PMID: 41204734, DOI: 10.1177/25785125251394916.Peer-Reviewed Original ResearchAltmetricCannabinoid 1 receptor availability in posttraumatic stress disorder: A positron emission tomography study
Korem N, Bassir Nia A, Hillmer A, D’Souza D, Nabulsi N, Ropchan J, Huang Y, Cosgrove K, Levy I, Pietrzak R, Harpaz-Rotem I. Cannabinoid 1 receptor availability in posttraumatic stress disorder: A positron emission tomography study. Translational Psychiatry 2025, 15: 310. PMID: 40846835, PMCID: PMC12373994, DOI: 10.1038/s41398-025-03519-9.Peer-Reviewed Original ResearchCitationsAltmetricConceptsPathophysiology of posttraumatic stress disorderEmotional numbing symptomsCB1R availabilityPosttraumatic stress disorderEndocannabinoid systemStress disorderPositron emission tomographyTrauma-exposed participantsEndocannabinoid system's rolePositron emission tomography studiesCannabinoid receptor 1Emission tomography studiesMulti-faceted disorderFear learningCB1RSymptom expressionHealthy controlsCannabinoidDisordersTomography studiesEmission tomographyPreclinical studiesSymptomsHigher levelsReceptor 1Interactions of alcohol and the benzodiazepine inverse agonist in healthy male volunteers
Singh N, Petrakis I, Pittman B, Luddy C, Krystal J, DSouza D. Interactions of alcohol and the benzodiazepine inverse agonist in healthy male volunteers. Journal Of Psychopharmacology 2025, 39: 715-725. PMID: 40673436, DOI: 10.1177/02698811251330746.Peer-Reviewed Original ResearchMeSH Keywords and ConceptsConceptsBenzodiazepine partial inverse agonistPartial inverse agonistGABA-A receptorsEthanol intoxicationInverse agonistsGABA-ASedative effectsSedative effects of alcoholAlcohol intoxicationEffects of alcohol intoxicationBenzodiazepine inverse agonistGABA-A receptor subtypesHealthy male volunteersExtrasynaptic GABA-A receptorsWithin-subject designEffects of alcoholStandard alcoholic drinksInteraction of alcoholAffect ScaleAlcohol effectsGABAergic modulationMale volunteersIntravenous alcoholBenzodiazepinesAlcohol drinkingPsilocybin’s Effects on Headache Frequency are Not Related to Acute Psychedelic Effects or Measures of Mental Health: Secondary Analysis of Clinical Trials in Migraine and Cluster Headache (P7-12.001)
Schindler E, Gottschalk C, D'Souza D. Psilocybin’s Effects on Headache Frequency are Not Related to Acute Psychedelic Effects or Measures of Mental Health: Secondary Analysis of Clinical Trials in Migraine and Cluster Headache (P7-12.001). Neurology 2025, 104 DOI: 10.1212/wnl.0000000000210945.Peer-Reviewed Original ResearchAltmetricAddressing blinding in classic psychedelic studies with innovative active placebos
Aday J, Simonsson O, Schindler E, D’Souza D. Addressing blinding in classic psychedelic studies with innovative active placebos. The International Journal Of Neuropsychopharmacology 2025, 28: pyaf023. PMID: 40183712, PMCID: PMC12038243, DOI: 10.1093/ijnp/pyaf023.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsActive placeboClassic psychedelicsPsychedelic studiesAcute psychoactive effectsModerate-to-high dosesPlacebo conditionNeuropsychiatric disordersPsychoactive effectsAcute physiological effectsTherapeutic effectPsychedelicsLow-dose administrationBlind integrationLack of therapeutic effectAcute effectsReview interventionsPlaceboShort-actingClinical trialsPharmacological agentsImproved blindingAncillary strategiesTrialsPhysiological effectsDisorders
Clinical Trials
Current Trials
Brain Changes and Cannabis Use Study
IRB ID2000032181RolePrincipal InvestigatorPrimary Completion Date05/31/2027Recruiting ParticipantsGenderBothAge18 years - 75 yearsM1 Schizophrenia PET Study
IRB ID2000031171RoleSub InvestigatorPrimary Completion Date04/30/2023Recruiting ParticipantsGenderBothAge18 years - 55 yearsSchizophrenia Spectrum Biomarkers Consortium (SSBC)
IRB ID2000029485RoleSub InvestigatorPrimary Completion Date12/31/2030Recruiting ParticipantsImaging Cannabinoid Receptors Using Positron Emission Tomography (PET) Scanning
IRB ID1005006735RolePrincipal InvestigatorPrimary Completion Date12/31/2016Recruiting ParticipantsGenderMaleAge18 years - 55 yearsA longitudinal study of the effects of cannabis exposure on neuro-development in adolescents and young adults
IRB ID2000024543RolePrincipal InvestigatorPrimary Completion Date01/31/2021Recruiting ParticipantsGenderBothAge13 years - 25 years
Academic Achievements & Community Involvement
Copy Link
Activities
activity Cognitive Rehabilitation in Schizophrenia - D-serine Facilitation
01/01/2008 - PresentResearchDetailsIndiaAbstract/SynopsisClinical trial of the combination of D-serine (Gly site agonist) and computerized cognitive retraining to improve cognition in individuals with schizophrenia
Honors
honor Board Member Elect
03/24/2022International AwardSchizophrenia International Research SocietyDetailsUnited States
News
Copy Link
News
- March 17, 2026Source: CNN (with Dr. Deepak D'Souza)
Scientists Say Marijuana Doesn’t Ease Anxiety or Other Mental Health Conditions
- March 11, 2026
Yale and McGill Collaborate to Expand Cannabis Research
- March 10, 2026Source: JAMA Internal Medicine
Cannabis and Mental Health: A Review
- February 16, 2026Source: Yale News
Legal Weed, Lingering Concerns
Get In Touch
Copy Link
Contacts
Psychiatry
950 Campbell Avenue
West Haven, CT 06516
United States