PT - JOURNAL ARTICLE AU - Jaime J. Castrellon AU - Kendra L. Seaman AU - Jennifer L. Crawford AU - Jacob S. Young AU - Christopher T. Smith AU - Linh C. Dang AU - Ming Hsu AU - Ronald L. Cowan AU - David H. Zald AU - Gregory R. Samanez-Larkin TI - Individual differences in dopamine are associated with reward discounting in clinical groups but not in healthy adults AID - 10.1101/383810 DP - 2018 Jan 01 TA - bioRxiv PG - 383810 4099 - http://biorxiv.org/content/early/2018/08/02/383810.short 4100 - http://biorxiv.org/content/early/2018/08/02/383810.full AB - Some people are more willing to make immediate, risky, or costly reward-focused choices than others, which has been hypothesized to be associated with individual differences in dopamine (DA) function. In two studies using PET imaging, one empirical (Study 1: N=144 males and females) and one meta-analytic (Study 2: N=307), we sought to characterize associations between individual differences in DA and time, probability, and physical effort discounting in human adults. Study 1 demonstrated that individual differences in DA D2-like receptors were not significantly associated with time, probability, or physical effort discounting of monetary rewards in healthy humans. Meta-analytic results for temporal discounting corroborated our empirical finding for minimal effect of DA measures on discounting in healthy individuals, but suggested that associations between individual differences in DA and reward discounting depend on clinical features. Addictions were characterized by negative correlations between DA and discounting but other clinical conditions like Parkinson’s Disease, obesity, and ADHD were characterized by positive correlations between DA and discounting. Together the results suggest that trait differences in discounting in healthy adults do not appear to be strongly associated with individual differences in D2-like receptors. The difference in meta-analytic correlation effects between healthy controls and individuals with psychopathology suggests that individual difference findings related to DA and reward discounting in clinical samples may not be reliably generalized to healthy controls, and vice-versa.Significance Statement Decisions to forgo larger rewards for smaller ones due to increasing time delays, uncertainty, or physical effort have been linked to differences in dopamine (DA) function, which is disrupted in some forms of psychopathology. It remains unclear whether alterations in DA function associated with psychopathology also extend to explaining associations between baseline DA function and decision making in healthy individuals. We show that individual differences in dopamine D2 receptor availability are not related to monetary discounting of time, probability, or physical effort in healthy individuals. By contrast, we suggest that psychopathology accounts for observed inconsistencies in the relationship between measures of dopamine function and reward discounting behavior.Author Note Some of the results reported in this manuscript were presented in a poster at the Society for Neuroeconomics (2017). JLC is now in the Department of Psychological and Brain Sciences at Washington University in St. Louis. JSY is now in the Department of Neurological Surgery at University of California, San Francisco.Data Data and code used in the manuscript can be viewed and downloaded from OSF: https://osf.io/htq56/Author ContributionsJJC, MH, DHZ, and GRSL designed the research; JJC, JLC, JSY, and RLC carried out the experiments; JJC, CTS, LCD, JLC processed the PET imaging data; JJC and KLS analyzed the behavioral and neuroimaging data in consultation with GRSL; JJC, KLS, and GRSL wrote the paper which was revised by DHZ and based on comments from all other authors.This research was supported by National Institute on Aging Pathway to Independence Award R00-AG042596, National Institute on Aging grant R01-AG044838, and National Institute on Drug Abuse grant R21-DA033611. We thank Kevin S. LaBar for comments on portions of the manuscript.