title: Hippocampal volumes in bipolar disorders: opposing effects of illness burden and lithium treatment.
abstract: OBJECTIVE
  Hippocampal volume decrease associated with illness burden is among the most replicated findings in unipolar depression. The absence of hippocampal volume changes in most studies of individuals with bipolar disorder (BD) may reflect neuroprotective effects of lithium (Li).
  
  
  METHODS
  We recruited 17 BD patients from specialized Li clinics, with at least two years of regularly monitored Li treatment (Li group), and compared them to 12 BD participants with < 3 months of lifetime Li exposure and no Li treatment within two years prior to the scanning (non-Li group) and 11 healthy controls. All BD patients had at least 10 years of illness and five episodes. We also recruited 13 Li-naïve, young BD participants (15-30 years of age) and 18 sex- and age-matched healthy controls. We compared hippocampal volumes obtained from 1.5-T magnetic resonance imaging (MRI) scans using optimized voxel-based morphometry with small volume correction.
  
  
  RESULTS
  The non-Li group had smaller left hippocampal volumes than controls (corrected p < 0.05), with a trend for lower volumes than the Li group (corrected p < 0.1), which did not differ from controls. Young, Li-naïve BD patients close to the typical age of onset had comparable hippocampal volumes to controls.
  
  
  CONCLUSIONS
  Whereas patients with limited lifetime Li exposure had significantly lower hippocampal volumes than controls, patients with comparable illness burden, but with over two years of Li treatment, or young Li-naïve BD patients, showed hippocampal volumes comparable to controls. These results provide indirect support for neuroprotective effects of Li and negative effects of illness burden on hippocampal volumes in bipolar disorders.
authors.affiliation: Department of Psychiatry, Dalhousie University, Halifax, NS, Canada. tomas.hajek@dal.ca
authors.forename: Tomas
authors.initials: T
authors.lastname: Hajek
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Cullis
authors.forename: Tomas
authors.initials: T
authors.lastname: Novak
authors.forename: Miloslav
authors.initials: M
authors.lastname: Kopecek
authors.forename: Cyril
authors.initials: C
authors.lastname: Höschl
authors.forename: Ryan
authors.initials: R
authors.lastname: Blagdon
authors.forename: Claire
authors.initials: C
authors.lastname: O'Donovan
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.forename: L Trevor
authors.initials: LT
authors.lastname: Young
authors.forename: Glenda
authors.initials: G
authors.lastname: Macqueen
authors.forename: Martin
authors.initials: M
authors.lastname: Alda
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D018692:Antimanic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001714:Bipolar Disorder / Q000188:drug therapy / Q000473:pathology / Q000523:psychology; D002170:Canada; D017281:Cost of Illness; D018153:Czech Republic; D005260:Female; D006624:Hippocampus / Q000187:drug effects* / Q000473:pathology*; D006801:Humans; D018021:Lithium Chloride / Q000494:pharmacology / Q000627:therapeutic use*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D055815:Young Adult
chemical_list: D018692:Antimanic Agents; D018021:Lithium Chloride