Nehal P. Vadhan, Ph.D.
Dr. Nehal Vadhan is an Assistant Professor of Clinical Psychology in the Department of Psychiatry at the College of Physicians and Surgeons of Columbia University, and Director of the Neuropsychology Research Laboratory in the Substance Use Research Center at the New York State Psychiatric Institute. Dr. Vadhan received his Ph.D. in 2003 from Hofstra University in Hempstead, NY, where he studied neuropsychological and social cognitive function in individuals with schizophrenia, with and without substance abuse, in the laboratory of Dr. Mark Serper. He completed his postdoctoral fellowship at Columbia University in substance abuse research in 2005, where he received training in human preclinical research under Dr. Richard Foltin, and in cognitive-behavioral treatment of substance use disorders under Dr. Kenneth Carpenter. Since coming to Columbia, Dr. Vadhan has focused on studying the long-term and acute neuropsychological sequelae of cocaine and marijuana use, and he has received a Career Development Award (K01) from the National Institute on Drug Abuse (NIDA), and a Young Investigator Award from the National Alliance on Research in Schizophrenia and Depression (NARSAD) to support this work. He also works as a clinician in the Division's Substance Use Treatment and Research Service, and as a clinical neuropsychologist in private practice.

E-Mail: npv2101@columbia.edu

Current Research Activities:
Neuropsychological sequelae of cocaine and marijuana use.
The potential effects of drugs of abuse on cognitive functioning are of significant clinical and public concern. However, research findings in this area remain inconclusive. One reason for this may be the lack of convergence between two major paradigms used to assess the effects of drugs of abuse on neurobehavioral functioning: neuropsychology and behavior pharmacology. Thus, Dr. Vadhan and colleagues are developing a translational laboratory model that integrates these approaches. Research projects in this area include studies of the acute effects of marijuana on decision-making, studies of stimulus-response learning in cocaine-abusing individuals (ongoing collaboration with Drs. Mark Gluck and Catherine Myers, from Rutgers University), and studies of neuropsychological differences in long-term and short-term cocaine abusers.

Differences in substance-abusing individuals seeking and not seeking treatment.
While substance abuse remains prevalent in American society, only a minority of abusers are seeking professional treatment for their abuse at any given time. Preliminary data suggest that treatment seekers and nontreatment seekers differ in substantial ways, including severity of substance dependence, subjective distress at substance use, and psychiatric comorbidity. Further exploration of neuropsychiatric differences between these subgroups may aid in understanding the seeking of, engagement in, and clinical response to substance abuse treatment. Research projects in this area include comparisons of decision-making, attentional bias towards cocaine-related stimuli, and expectancy of cocaine's effects, between cocaine-dependent treatment seekers and nontreatment seekers.

Marijuana use and Psychosis

Although associations have been reported between marijuana use and the onset of psychotic disorder in individuals at risk to develop a psychotic disorder, the direct role of marijuana in producing such effects is unknown. Controlled laboratory data examining this issue are needed to help inform this debate. Research projects in this area include an examination of the acute subjective and neurocognitive effects of smoked marijuana on individuals considered at-risk to develop a psychotic disorder.

Selected Peer-Reviewed Publications:

Vadhan, N.P., Myers, C.E., Rubin, E.R., Shohamy, D., Foltin, R.W., & Gluck, M. (2008). Stimulus-response learning in long-term cocaine users: Acquired equivalence and probabilistic category learning. Drug and Alcohol Dependence, 93, 155-162.

Vadhan, N.P., Hart, C.L., van Gorp, W.G., Gunderson, E.W., Haney, M., & Foltin, R.W. (2007). Acute effects of smoked marijuana on decision-making, as assessed by a modified Gambling task, in experienced marijuana users. Journal of Clinical and Experimental Neuropsychology, 29, 357-364.

Vadhan, N.P., Carpenter, K.M., Copersino, M.L., Hart, C.L., Foltin, R.W., & Nunes, E.V. (2007). Attentional bias towards cocaine-related stimuli: relationship to treatment-seeking for cocaine dependence. American Journal of Drug and Alcohol Abuse, 33, 727-736.

Recent publications