title: Adolescent smokers show decreased brain responses to pleasurable food images compared with nonsmokers.
abstract: BACKGROUND
  Nicotine acts on the mesocorticolimbic circuits of the brain leading to the release of dopamine. Repeated elevations of dopamine in the brain may cause smokers to become less sensitive to "natural reinforcers." To test the theory that adolescents with low nicotine exposure may already have decreased activation when exposed to a natural reinforcer, we looked at the effect of visual cues representing "pleasurable" food on light adolescent smokers compared with nonsmokers.
  
  
  METHODS
  Twelve adolescent light smokers (aged 13-17 years, smoked 1-5 cigarettes/day) and 12 nonsmokers (aged 13-17 years, never smoked a cigarette) from the San Francisco Bay Area underwent functional magnetic resonance imaging scanning. During scanning, they viewed blocks of photographic images representing pleasurable foods (sweet, high fat, and salty foods) and control cues.
  
  
  RESULTS
  Smokers reported smoking a mean of 3.6 cigarettes/day. There was no difference in body mass index between groups (24.1 vs. 24.0, respectively, p = .99). Food images elicited greater activations in nonsmokers in multiple areas including the insula (T = 4.38, p < .001), inferior frontal region (T = 5.12, p < .001), and rolandic operculum (T = 6.18, p < .001). There were no regions where smokers demonstrated greater blood oxygenation level-dependent activations compared with nonsmokers when viewing food versus neutral images.
  
  
  CONCLUSIONS
  The finding of decreased activation to pleasurable food among adolescent light smokers supports the theory that these adolescents are displaying decreased sensitivity to at least one natural reinforcer. This also supports the theory that nicotine may affect the brain early in the trajectory of smoking, thus underscoring the need for early intervention among adolescent smokers.
authors: Division of Adolescent Medicine, University of California-San Francisco, 3333 California Street, San Francisco, CA 94118, USA. rubinsteinm@peds.ucsf.edu
authors: Mark L
authors: ML
authors: Rubinstein
authors: Tracy L
authors: TL
authors: Luks
authors: Wendy Y
authors: WY
authors: Dryden
authors: Michelle A
authors: MA
authors: Rait
authors: Gregory V
authors: GV
authors: Simpson
mesh_terms: D000293:Adolescent; D001921:Brain / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D016022:Case-Control Studies; D003463:Cues; D004298:Dopamine / Q000378:metabolism; D004435:Eating / Q000523:psychology; D005260:Female; D005502:Food; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009538:Nicotine / Q000008:administration & dosage / Q000009:adverse effects*; D010465:Perception / Q000187:drug effects / Q000502:physiology*; D012907:Smoking / Q000009:adverse effects / Q000523:psychology*
chemical_list: D009538:Nicotine; D004298:Dopamine