title: When less is more: a functional magnetic resonance imaging study of verbal working memory in remitted depressed patients.
abstract: BACKGROUND
  Patients with depression show abnormalities in the neural circuitry supporting working memory. However, it is unclear if these abnormalities are present in unmedicated remitted depressed patients. To address this question, the current study employed functional magnetic resonance imaging (fMRI), in combination with a simple verbal n-back task, in a cohort of unmedicated remitted depressed patients.
  
  
  METHODS
  We studied 15 healthy control subjects (HC) and 15 unmedicated remitted depressed patients (rMDD). Participants performed a verbal working memory task of varying cognitive load (n-back) while undergoing fMRI. We used multiple regression analyses to assess overall capacity (1-, 2-, 3-back versus 0-back) as well as quadratic modulation of cognitive demand.
  
  
  RESULTS
  Performance accuracy and response latency did not differ between groups, and overall capacity was similar. However, rMDD showed a positive quadratic load response in the bilateral hippocampus; the converse was true for HC.
  
  
  CONCLUSIONS
  Our data suggest that remitted depression was associated with a perturbed pattern of activation in the bilateral hippocampus during a verbal working memory task. We propose that a reduced ability to dampen task-irrelevant activity may reflect a neurobiological risk factor for recurrent depression.
authors.affiliation: Department of Psychology, Whitelands College, University of Roehampton, Holybourne Avenue, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Norbury
authors.affiliation: University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK.
authors.forename: B
authors.initials: B
authors.lastname: Godlewska
authors.affiliation: University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Cowen
mesh_terms: D000328:Adult; D003865:Major Depressive Disorder / Q000503:physiopathology* / Q000628:therapy; D005260:Female; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology*; D012074:Remission Induction; D012307:Risk Factors; D055815:Young Adult