title: Brain-to-serum lithium ratio and age: an in vivo magnetic resonance spectroscopy study.
abstract: OBJECTIVE
  The authors' goal was to determine if there is an association between brain-to-serum lithium ratios and age.
  
  
  METHODS
  Lithium-7 magnetic resonance spectroscopy was used to measure in vivo brain lithium levels in nine children and adolescents (mean age=13.4 years, SD=3.6) and 18 adults (mean age=37.3, SD=9.1) with bipolar disorder.
  
  
  RESULTS
  Serum and brain lithium concentrations were positively correlated. Younger subjects had lower brain-to-serum concentration ratios than adults: 0.58 (SD=0.24) versus 0.92 (SD=0.36). The brain-to-serum concentration ratio correlated positively with age.
  
  
  CONCLUSIONS
  These observations suggest that children and adolescents may need higher maintenance serum lithium concentrations than adults to ensure that brain lithium concentrations reach therapeutic levels.
authors.affiliation: Brain Imaging Center, Consolidated Department of Psychiatry, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA. const@mclean.harvard.edu
authors.forename: Constance M
authors.initials: CM
authors.lastname: Moore
authors.forename: Christina M
authors.initials: CM
authors.lastname: Demopulos
authors.forename: Michael E
authors.initials: ME
authors.lastname: Henry
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Steingard
authors.forename: Linda
authors.initials: L
authors.lastname: Zamvil
authors.forename: Alain
authors.initials: A
authors.lastname: Katic
authors.forename: Janis L
authors.initials: JL
authors.lastname: Breeze
authors.forename: JoEllyn C
authors.initials: JC
authors.lastname: Moore
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Cohen
authors.forename: Perry F
authors.initials: PF
authors.lastname: Renshaw
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001714:Bipolar Disorder / Q000097:blood* / Q000188:drug therapy / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry; D002648:Child; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008094:Lithium / Q000032:analysis* / Q000097:blood* / Q000627:therapeutic use; D009682:Magnetic Resonance Spectroscopy; D008297:Male
chemical_list: D008094:Lithium