title: Hyperactivation to pleasant interoceptive stimuli characterizes the transition to stimulant addiction.
abstract: OBJECTIVE
  Altered interoception, how the brain processes afferents from the body, may contribute to the urge to take drugs, and subsequently, the development of addiction. Although chronic stimulant dependent individuals exhibit attenuated brain responses to pleasant interoceptive stimuli, it is unclear whether this deficit exists early-on in the process of transition to stimulant addiction.
  
  
  METHODS
  To this end, we compared problem stimulant users (PSU; n=18), desisted stimulant users (DSU; n=15), and stimulant naïve comparison subjects (CTL; n=15) during functional magnetic resonance imaging (fMRI) while they anticipated and experienced pleasant soft touch (slow brushstroke to the palm and forearm).
  
  
  RESULTS
  Groups did not differ in behavioral performance or visual analog scale ratings of soft touch stimuli. fMRI results indicated that PSU exhibited greater right anterior insula, left inferior frontal gyrus, and right superior frontal gyrus activation than DSU and CTL during the anticipation and experience of soft touch. Moreover, during the experience of soft touch, PSU demonstrated higher bilateral precentral gyrus/middle insula and right posterior temporal gyrus activation than DSU and CTL.
  
  
  CONCLUSIONS
  In contrast to chronic stimulant dependence, individuals who have recently developed stimulant use disorders show exaggerated neural processing of pleasant interoceptive stimuli. Thus, increased processing of body-relevant information signaling pleasant touch in those individuals who develop problem use may be a predictive interoceptive biomarker. However, future investigations will need to determine whether the combination of probing pleasant interoception using neuroimaging is sufficiently sensitive and specific to help identify individuals at high risk for future problem use.
authors.affiliation: Psychology Department, Queens College, City University of New York, 6530 Kissena Boulevard, Flushing, NY 11367-1597, USA; Psychiatry Department, University of California, San Diego, 8939 Villa La Jolla Drive, Suite 200, La Jolla, CA 92037-0855, USA. Electronic address: jennifer.stewart@qc.cuny.edu.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Stewart
authors.affiliation: Psychiatry Department, University of California, San Diego, 8939 Villa La Jolla Drive, Suite 200, La Jolla, CA 92037-0855, USA. Electronic address: acmay@ucsd.edu.
authors.forename: April C
authors.initials: AC
authors.lastname: May
authors.affiliation: Psychiatry Department, University of California, San Diego, 8939 Villa La Jolla Drive, Suite 200, La Jolla, CA 92037-0855, USA; Psychiatry Service, Veterans Affairs San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA. Electronic address: stapert@ucsd.edu.
authors.forename: Susan F
authors.initials: SF
authors.lastname: Tapert
authors.affiliation: Psychiatry Department, University of California, San Diego, 8939 Villa La Jolla Drive, Suite 200, La Jolla, CA 92037-0855, USA; Psychiatry Service, Veterans Affairs San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA. Electronic address: mpaulus@ucsd.edu.
authors.forename: Martin P
authors.initials: MP
authors.lastname: Paulus
mesh_terms: D000328:Adult; D019969:Amphetamine-Related Disorders / Q000503:physiopathology*; D016739:Behavior, Addictive / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology; D016022:Case-Control Studies; D019970:Cocaine-Related Disorders / Q000503:physiopathology*; D004644:Emotions / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008774:Methylphenidate / Q000009:adverse effects; D055698:Touch Perception / Q000502:physiology*
chemical_list: D008774:Methylphenidate
keywords: Amphetamine; Cocaine; Functional magnetic resonance imaging; Interoception; Reward