title: Light therapy and serotonin transporter binding in the anterior cingulate and prefrontal cortex.
abstract: OBJECTIVE
  To investigate the effects of light therapy on serotonin transporter binding (5-HTT BPND ), an index of 5-HTT levels, in the anterior cingulate and prefrontal cortices (ACC and PFC) of healthy individuals during the fall and winter. Twenty-five per cent of healthy individuals experience seasonal mood changes that affect functioning. 5-HTT BPND has been found to be higher across multiple brain regions in the fall and winter relative to spring and summer, and elevated 5-HTT BPND may lead to extracellular serotonin loss and low mood. We hypothesized that, during the fall and winter, light therapy would reduce 5-HTT BPND in the ACC and PFC, which sample brain regions involved in mood regulation.
  
  
  METHODS
  In a single-blind, placebo-controlled, counterbalanced, crossover design, [(11) C]DASB positron emission tomography was used measure 5-HTT BPND following light therapy and placebo conditions during fall and winter.
  
  
  RESULTS
  In winter, light therapy significantly decreased 5-HTT BPND by 12% in the ACC relative to placebo (F1,9 = 18.04, P = 0.002). In the fall, no significant change in 5-HTT BPND was found in any region across conditions.
  
  
  CONCLUSIONS
  These results identify, for the first time, a central biomarker associated with the intervention of light therapy in humans which may be applied to further develop this treatment for prevention of seasonal depression.
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.|Behavioural Neurobiology Laboratory and Campbell Family Mental Health Research Institute and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: S J
authors.initials: SJ
authors.lastname: Harrison
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: A E
authors.initials: AE
authors.lastname: Tyrer
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: R D
authors.initials: RD
authors.lastname: Levitan
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Houle
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: A A
authors.initials: AA
authors.lastname: Wilson
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.|Behavioural Neurobiology Laboratory and Campbell Family Mental Health Research Institute and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: J N
authors.initials: JN
authors.lastname: Nobrega
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: P M
authors.initials: PM
authors.lastname: Rusjan
authors.affiliation: CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: J H
authors.initials: JH
authors.lastname: Meyer
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D018592:Cross-Over Studies; D005260:Female; D006179:Gyrus Cinguli / Q000378:metabolism*; D006801:Humans; D008297:Male; D010789:Phototherapy / Q000295:instrumentation / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D017397:Prefrontal Cortex / Q000378:metabolism*; D011485:Protein Binding; D012621:Seasons; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D016037:Single-Blind Method; D055815:Young Adult
chemical_list: D015415:Biomarkers; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins
keywords: anterior cingulate cortex; light therapy; seasonal affective disorder; serotonin; serotonin transporter