Rajiv Radhakrishnan, MBBS, MD, FAPA
Associate Professor Adjunct in PsychiatryDownloadHi-Res Photo
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Associate Professor, Radiology and Biomedical Imaging
Affiliated Faculty, Yale Institute for Global Health
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Titles
Associate Professor Adjunct in Psychiatry
Associate Professor, Radiology and Biomedical Imaging; Affiliated Faculty, Yale Institute for Global Health
Appointments
Psychiatry
Associate Professor AdjunctPrimaryRadiology & Biomedical Imaging
Associate Professor on TermSecondary
Other Departments & Organizations
- Center for Brain & Mind Health
- Interventional Psychiatry Service
- MR Core
- NeuroPET Imaging Program
- PET Core
- Psychiatry
- Radiology & Biomedical Imaging
- Yale Biomedical Imaging Institute
- Yale Center for the Science of Cannabis and Cannabinoids
- Yale Institute for Global Health
- Yale New Haven Health System
Education & Training
- MHS
- Yale University (2021)
- Fellowship
- Yale School of Medicine (2018)
- Residency
- Yale School of Medicine (2016)
- Internship
- Long Island Jewish Medical Center (2013)
- MD
- St. John's Medical College (2008)
- MBBS
- St John's Medical College, Medicine (2003)
Board Certifications
Addiction Medicine (Preventive Medicine)
- Certification Organization
- AB of Preventive Medicine
- Original Certification Date
- 2020
Research
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Overview
Medical Research Interests
Marijuana Abuse; Psychoses, Substance-Induced; Schizophrenia
Public Health Interests
Mental Health; Substance Use, Addiction
ORCID
0000-0002-8220-655X- View Lab Website
Radhakrishnan Lab
Research at a Glance
Yale Co-Authors
Frequent collaborators of Rajiv Radhakrishnan's published research.
Publications Timeline
A big-picture view of Rajiv Radhakrishnan's research output by year.
Research Interests
Research topics Rajiv Radhakrishnan is interested in exploring.
Deepak Cyril Dsouza, MBBS, MD
David Matuskey, MD
Richard Carson, PhD
Takuya Toyonaga, MD, PhD
Nabeel Nabulsi, PhD
Jean-Dominique Gallezot, PhD
36Publications
859Citations
Schizophrenia
Marijuana Abuse
Publications
2025
Exceptional brain PET images from the NeuroEXPLORER: scans with targeted radiopharmaceuticals and comparison to HRRT
Volpi T, Toyonaga T, Khattar N, Gallezot J, Naganawa M, Vanderlinden G, Honhar P, Zeng T, Fontaine K, Mulnix T, Hu L, Sun X, Henry S, Matuskey D, Radhakrishnan R, Guo L, Hu Y, Zhang J, Zheng X, Nabulsi N, Huang Y, Badawi R, Cherry S, Hillmer A, Jones T, Liu C, Morris E, Qi J, Li H, Carson R. Exceptional brain PET images from the NeuroEXPLORER: scans with targeted radiopharmaceuticals and comparison to HRRT. European Journal Of Nuclear Medicine And Molecular Imaging 2025, 53: 2110-2121. PMID: 41177836, PMCID: PMC12860869, DOI: 10.1007/s00259-025-07605-4.Peer-Reviewed Original ResearchCitationsAltmetricConceptsStandardized uptake valueTargeted radiopharmaceuticalsDopamine systemMultiple cortical areasSerotonin transporterRaphe nucleusMeasurement of tracer uptakeBrain regionsBrain structuresSubcortical nucleiPositron emission tomographyCortical areasSynaptic densityPET researchFocal uptakePaired scansUptake valueTracer uptakePET systemGray matterEarly imagesEmission tomographyHealthy individualsTracer deliveryNeuroExplorerMeasuring Dopamine Transporter Availability and Synaptic Density in Parkinson's Disease: A Dual‐Tracer Positron Emission Tomography Imaging Study
Sadabad F, Volpi T, Honhar P, Tinaz S, Dias M, Toyonaga T, Naganawa M, Gallezot J, Yang Y, Ibrahim W, Pittman B, Cayir S, Radhakrishnan R, Angarita G, Holmes S, Comley R, Carson R, Finnema S, Matuskey D. Measuring Dopamine Transporter Availability and Synaptic Density in Parkinson's Disease: A Dual‐Tracer Positron Emission Tomography Imaging Study. Movement Disorders 2025, 40: 2678-2687. PMID: 41040062, DOI: 10.1002/mds.70041.Peer-Reviewed Original ResearchAltmetricMeSH Keywords and ConceptsConceptsC-UCB-JDopamine transporterHealthy controlsVentral striatumDisease stageSubstantia nigraSynaptic densityParkinson's diseaseDopamine transporter availabilityPositron emission tomography imaging studiesSynaptic vesicle glycoprotein 2AAssessment of synaptic densityDopaminergic denervationBetween-group differencesTransporter availabilityBinding potentialNigrostriatal regionDisease durationDual-tracerImaging studiesPatientsPET imagingPresynaptic degenerationPD patientsDopamineCarotid Artery Image-Derived Blood Time-Activity Curves on the NeuroEXPLORER: Initial Multitracer Validation Against Arterial Sampling.
Volpi T, Gallezot J, Henry S, Dias M, Khattar N, Toyonaga T, Fontaine K, Mulnix T, Zhang J, Guo L, Gravel P, Radhakrishnan R, Hillmer A, Matuskey D, Carson R. Carotid Artery Image-Derived Blood Time-Activity Curves on the NeuroEXPLORER: Initial Multitracer Validation Against Arterial Sampling. Journal Of Nuclear Medicine 2025, 66: 1993-2001. PMID: 41043999, PMCID: PMC12676648, DOI: 10.2967/jnumed.125.270414.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsArea under the curveCommon carotidTime-activity curvesLate area under the curveMethods:Carotid arteryRegions-of-interestResults:Blood samplesPartial volume effectsImage-derived input functionArterial blood samplesArterial input functionAlternative to arterial blood samplingBlood time-activity curvesPET kinetic modelingGold standardInput functionBackground activityArterial samplesCarotidBrain-dedicated PET scannersBrain PETEffects of Age and BMI on Histamine H3 Receptor Availability in Healthy Humans
Yang Y, Ibrahim W, Gravel P, Pittman B, Hoye J, Cool R, Sadabad F, Zheng M, Pittenger C, Gallezot J, Carson R, Huang H, Radhakrishnan R, Matuskey D. Effects of Age and BMI on Histamine H3 Receptor Availability in Healthy Humans. Molecular Imaging And Biology 2025, 27: 832-838. PMID: 40938339, DOI: 10.1007/s11307-025-02047-8.Peer-Reviewed Original ResearchConceptsHigh-resolution research tomographBody mass indexPositron emission tomographyEffects of ageAnterior cingulate cortexPotential confounding effects of ageAge-related declineTwo-tissue compartment modelCingulate cortexReceptor availabilityFrontal cortexParietal cortexOlfactory cortexSubcortical regionsHealthy humansRegional VTCortexConfounding effects of ageCerebellum cortexEmission tomographyTwo-tissueMass indexHealthy individualsInsulaAssessed alterationsGenerating synthetic brain PET images of synaptic density based on MR T1 images using deep learning
Zheng X, Worhunsky P, Liu Q, Guo X, Chen X, Sun H, Zhang J, Toyonaga T, Mecca A, O’Dell R, van Dyck C, Angarita G, Cosgrove K, D’Souza D, Matuskey D, Esterlis I, Carson R, Radhakrishnan R, Liu C. Generating synthetic brain PET images of synaptic density based on MR T1 images using deep learning. EJNMMI Physics 2025, 12: 30. PMID: 40163154, PMCID: PMC11958861, DOI: 10.1186/s40658-025-00744-5.Peer-Reviewed Original ResearchCitationsAltmetricConceptsCannabis use disorderStructural similarity indexPET imagingImages of higher qualityMR-T1 imagesMean square errorUse disorderEncoder-decoderDeep learningCross-validation processData-driven approachDiagnostic categoriesLow-dose scansPredicted imageTemporal regionsBrain disordersGround truthT1-weighted MRISynaptic densityHuman brainSimilarity indexDisordersSevere neurological disordersTranslation accuracyNoise reductionInternational perspectives on physician knowledge, attitudes, and practices related to medical cannabis
Syed S, Singh J, Elkholy H, Palavra I, Tomicevic M, Eric A, da Costa M, Guloksuz S, Radhakrishnan R. International perspectives on physician knowledge, attitudes, and practices related to medical cannabis. Frontiers In Public Health 2025, 13: 1463871. PMID: 40051509, PMCID: PMC11882600, DOI: 10.3389/fpubh.2025.1463871.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsPhysicians' knowledgeStrength of evidenceMedical cannabisCross-sectional survey of physiciansSurvey of physiciansCross-sectional surveyYears of clinical experienceNegative health outcomesCannabis useClinical experienceRefractory chronic neuropathic painClinical decision-makingHealth outcomesPhysicians' attitudesPhysicians' willingnessChronic neuropathic painMedical use of cannabisRisk of psychosisDaily cannabis useMedication useDescriptive statisticsRisk of addictionMedical indicationsUse of cannabisPhysicians
2024
Cognitive functioning and functional ability in women with schizophrenia and homelessness
Menon J, Kantipudi S, Mani A, Radhakrishnan R. Cognitive functioning and functional ability in women with schizophrenia and homelessness. Schizophrenia Research Cognition 2024, 39: 100338. PMID: 39610698, PMCID: PMC11603006, DOI: 10.1016/j.scog.2024.100338.Peer-Reviewed Original ResearchCitationsConceptsWorld Health Organization Disability Assessment ScaleFrontal Assessment BatteryCognitive functionCognitive dysfunctionScale for Assessment of Negative SymptomsAssessment of Negative SymptomsDisability Assessment ScaleStudies of schizophreniaHigher cognitive dysfunctionPremorbid level of functionCognitive function of womenNegative symptomsAssessment BatteryPremorbid levelSchizophreniaCognitive AssessmentCognitive impairmentSemi-structured proformaDementia ScaleLevel of functionAssessment ScalePsychosocial factorsHigher literacy levelsGroup of womenFunctional abilityEffects of Buprenorphine, Methadone, and Substance Use on COVID-19 Morbidity and Mortality
Christian N, Zhou X, Radhakrishnan R. Effects of Buprenorphine, Methadone, and Substance Use on COVID-19 Morbidity and Mortality. Journal Of Addiction Medicine 2024, 19: 223-226. PMID: 39475125, DOI: 10.1097/adm.0000000000001386.Peer-Reviewed Original ResearchCitationsMeSH Keywords and ConceptsConceptsActive substance useSubstance useAssociated with increased morbidityDuration of hospitalizationCOVID-19 outcomesOpioid useSubstance use disordersImpact of substance useCOVID-19 infectionEffects of buprenorphineOpioid use disorderRetrospective cohort studyUse disorderAll-Cause MortalityCOVID-19 positive patientsUrine toxicologyMultivariate logistic regressionAssociated with statistically significant increasesMedical comorbidityStatistically significant differenceMOUD treatmentStatistically significant increaseAssociated with worse COVID-19 outcomesCOVID-19 morbidityUrban hospital system11C-UCB-J PET imaging is consistent with lower synaptic density in autistic adults
Matuskey D, Yang Y, Naganawa M, Koohsari S, Toyonaga T, Gravel P, Pittman B, Torres K, Pisani L, Finn C, Cramer-Benjamin S, Herman N, Rosenthal L, Franke C, Walicki B, Esterlis I, Skosnik P, Radhakrishnan R, Wolf J, Nabulsi N, Ropchan J, Huang Y, Carson R, Naples A, McPartland J. 11C-UCB-J PET imaging is consistent with lower synaptic density in autistic adults. Molecular Psychiatry 2024, 30: 1610-1616. PMID: 39367053, DOI: 10.1038/s41380-024-02776-2.Peer-Reviewed Original ResearchCitationsAltmetricConceptsPositron emission tomographySynaptic densityAutistic adultsBrain regionsAutistic featuresClinical phenotype of autismNon-autistic participantsPhenotype of autismNon-autistic individualsRelationship to clinical characteristicsSynaptic vesicle glycoprotein 2AAssociated with clinical measuresPost-mortem studiesPositron emission tomography scanPrefrontal cortexClinician ratingsAutism groupNeural basisBrain areasNeural processesBetween-group differencesVolumetric differencesBinding potentialDensity of synapsesAutismEfficacy and Safety of Ketamine/Esketamine in Bipolar Depression in a Clinical Setting.
Santucci M, Ansari M, Nikayin S, Radhakrishnan R, Rhee T, Wilkinson S. Efficacy and Safety of Ketamine/Esketamine in Bipolar Depression in a Clinical Setting. The Journal Of Clinical Psychiatry 2024, 85 PMID: 39361411, DOI: 10.4088/jcp.24m15376.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsBipolar depressionAcute seriesRisk of affective switchDiagnosis of bipolar depressionRefractory bipolar depressionAcute phaseMADRS scoreAffective switchIntranasal esketamineManic episodesBipolar disorderCohort of patientsAttending psychiatristsSource of morbidityEsketamineSample of patientsIV ketamineMaintenance treatmentDepressionClinical responseHeightened riskClinical outcomesMania/hypomaniaKetamineKetamine/esketamine
Clinical Trials
Current Trials
Brain Changes and Cannabis Use Study
IRB ID2000032181RoleSub InvestigatorPrimary Completion Date05/31/2027Recruiting ParticipantsGenderBothAge18 years - 75 yearsM1 Schizophrenia PET Study
IRB ID2000031171RolePrincipal InvestigatorPrimary Completion Date04/30/2023Recruiting ParticipantsGenderBothAge18 years - 55 yearsImaging cortisol metabolism in liver, adipose tissue and brain with a novel PET radioligand
IRB ID2000029576RoleSub InvestigatorPrimary Completion Date06/30/2024Recruiting ParticipantsSchizophrenia Spectrum Biomarkers Consortium (SSBC)
IRB ID2000029485RoleSub InvestigatorPrimary Completion Date12/31/2030Recruiting ParticipantsTesting a Computationally-Informed, Personalized Intervention for Hallucinations
IRB ID2000024774RoleSub InvestigatorPrimary Completion Date03/31/2024Recruiting ParticipantsGenderBothAge18 years - 65 years
Academic Achievements & Community Involvement
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Activities
activity American Society of Clinical Psychopharmacology (ASCP)
05/01/2017 - PresentProfessional OrganizationsCommittee Memberactivity Schizophrenia International Research Society (SIRS)
07/31/2019 - PresentProfessional OrganizationsCommittee Memberactivity Journal of Dual Diagnosis
09/11/2019 - PresentJournal ServiceAssociate Editoractivity Yale University Human Investigation Committee (HIC)
09/01/2016 - PresentCommitteesMemberactivity Medical Research Council (MRC), UK
2019 - PresentPeer Review Groups and Grant Study SectionsAd-hoc reviewer
Honors
honor NIH Early Career Reviewer
10/07/2020National AwardNIH CSRDetailsUnited Stateshonor 2020 CPDD Travel Award for Early Career Investigators
05/12/2020International AwardCollege on Problems of Drug Dependence (CPDD)DetailsUnited Stateshonor ISCTM 2020 New Investigator Award
12/20/2019International AwardInternational Society for CNS Clinical Trials Methodology (ISCTM)DetailsUnited Stateshonor Alavi-Mandell Award
04/16/2019International AwardSociety for Nuclear Medicine and Molecular Imaging (SNMMI)DetailsUnited Stateshonor American College of Neuropsychopharmacology Travel Award 2018
06/30/2018International AwardDetailsUnited States
News
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News
- December 13, 2024
Five Faculty Elected to Associate Membership of ACNP
- October 02, 2024
Bipolar Disorder Patients Respond to Ketamine, Esketamine Treatment
- April 02, 2024Source: Molecular Psychiatry
Substance Use and Spine Density: A Systematic Review and Meta-Analysis of Preclinical Studies
- December 18, 2022
Radhakrishnan Named Co-Medical Director of Yale PET Center
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