Rajiv Radhakrishnan, MBBS, MD, FAPA
Associate Professor Adjunct in PsychiatryDownloadHi-Res Photo
Cards
Additional Titles
Associate Professor, Radiology and Biomedical Imaging
Affiliated Faculty, Yale Institute for Global Health
Contact Info
About
Copy Link
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
Education & Training
- MHS
- Yale University (2021)
- 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
Copy Link
Overview
Medical Research Interests
Marijuana Abuse; Psychoses, Substance-Induced; Schizophrenia
Public Health Interests
Substance Use, Addiction; Mental Health
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
Richard Carson, PhD
David Matuskey, MD
Nabeel Nabulsi, PhD
Takuya Toyonaga, MD, PhD
Mika Naganawa, PhD
40Publications
895Citations
Schizophrenia
Marijuana Abuse
Publications
2026
Widespread synaptic density loss in schizophrenia follows molecular and network architecture
Chopra S, Worhunsky P, Naganawa M, Zhang X, Segal A, Labache L, Orchard E, Cropley V, Wood S, Angarita G, Cosgrove K, Matuskey D, Nabulsi N, Huang Y, Carson R, Esterlis I, Skosnik P, D’Souza D, Holmes A, Radhakrishnan R. Widespread synaptic density loss in schizophrenia follows molecular and network architecture. Molecular Psychiatry 2026, 1-12. PMID: 42350786, DOI: 10.1038/s41380-026-03717-x.Peer-Reviewed Original ResearchAltmetricConceptsGray matter volume alterationsLeft hemisphereVolume alterationsInferior frontal areasSynaptic pathologySynaptic density lossAnatomical magnetic resonance imagingConverging neuroimagingLeft-lateralisedNeurochemical systemsSchizophrenia pathogenesisSchizophreniaPost-mortem evidenceHippocampal areaFrontal areasNetwork diffusion modelSynaptic densityHealthy controlsMagnetic resonance imagingIn vivo evidenceDensity alterationsResonance imagingSource of pathologyHemisphereDensity lossLower Muscarinic M1 Receptor Availability in Schizophrenia: In Vivo PET Evidence
Volpi T, Radhakrishnan R, Hird R, Naganawa M, Nabulsi N, Najafzadeh S, Jacutin-Porte S, Labaree D, Carson R, Huang Y, D'Souza D. Lower Muscarinic M1 Receptor Availability in Schizophrenia: In Vivo PET Evidence. Biological Psychiatry 2026 PMID: 42285196, DOI: 10.1016/j.biopsych.2026.06.002.Peer-Reviewed Original ResearchAltmetricConceptsSZ patientsHealthy controlsNeurobiology of schizophreniaIn vivo quantificationDistribution volume ratioMuscarinic M1 receptorsHigh-resolution research tomographAgonist xanomelineReceptor availabilityNon-dopaminergic medicationsSchizophreniaSubcortical regionsWhole-brainEffect sizeRelationship to clinical featuresM1 receptorsPostmortem evidenceSubgroup of patientsExploratory analysisGray matter fractionDeficitsPostmortem dataIn vivo findingsClinical measuresClinical featuresEffects of Age and BMI on Histamine H3 Receptor Availability in Healthy Humans (P3-12.005)
Yang Y, Ibrahim W, Gravel P, pittman B, Hoye J, Sadabad F, Cool R, 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 (P3-12.005). Neurology 2026, 106 DOI: 10.1212/wnl.0000000000212778.Peer-Reviewed Original ResearchNeuroimaging evidence for a dopamine-independent association between motor cortex microstructure and Parkinson’s disease severity
Honhar P, Tinaz S, Ebrahimian Sadabad F, Dias M, Yang Y, Henry S, Hillmer A, Zakiniaeiz Y, Radhakrishnan R, Comley R, Zhang X, Hooker B, Zhang Y, Finnema S, Carson R, Scheinost D, Matuskey D. Neuroimaging evidence for a dopamine-independent association between motor cortex microstructure and Parkinson’s disease severity. Npj Parkinson's Disease 2026 PMID: 42248873, DOI: 10.1038/s41531-026-01411-x.Peer-Reviewed Original ResearchConceptsPD motor severityMotor severityDopamine transporterPrecentral gyrusParkinson's diseaseMotor cortexBrain microstructural alterationsDAT availabilityEarly-stage Parkinson's diseaseNeuroimaging evidenceDiffusion tensor imagingWhite matter regionsParietal lobeSub-corticalDopaminergic lossTensor imagingMatter regionsMean diffusivityMid-brainGyrusCortexMicrostructural alterationsMRI measurementsParkinson's disease severityNeurite orientation dispersionGeneration of brain PET synaptic density imaging from MRI and FDG-PET using a 3D Multi-stage Residual U-Net
Zheng X, Worhunsky P, Toyonaga T, Liu Q, Guo X, Zhou Y, Chen X, Zhou B, Mecca A, Chen M, O'Dell R, Van Dyck C, Carson R, Radhakrishnan R, Liu C. Generation of brain PET synaptic density imaging from MRI and FDG-PET using a 3D Multi-stage Residual U-Net. IEEE Transactions On Radiation And Plasma Medical Sciences 2026, PP: 1-1. DOI: 10.1109/trpms.2026.3690934.Peer-Reviewed Original Research
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 reduction
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 yearsSchizophrenia 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 yearsA longitudinal study of the effects of cannabis exposure on neuro-development in adolescents and young adults
IRB ID2000024543RoleSub InvestigatorPrimary Completion Date01/31/2021Recruiting ParticipantsGenderBothAge13 years - 25 years
Academic Achievements & Community Involvement
Copy Link
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
Copy Link
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
Get In Touch
Copy Link