title: Testing the cognitive effort hypothesis of cognitive impairment in major depression.
abstract: BACKGROUND
  It is widely accepted that depression is associated with deficits in a range of cognitive domains. However, there is no consensus regarding the neuropsychological profile in depression.
  
  
  OBJECTIVE
  The aim of the present report is to test the cognitive effort hypothesis as a possible framework for understanding the observed cognitive impairment in major depressive disorder (MDD), using the Delis Kaplan Executive Function system (D-KEFS).
  
  
  METHODS
  Twenty-four patients with recurrent MDD, in the acute phase of illness, were compared with a healthy control group. We expected that the patient group would show impairment on tests that measure higher-level effortful cognitive processing, whereas basic cognitive skills would be equal to the control group.
  
  
  RESULTS
  There were no differences between the two groups on measures of basic cognitive skills, except for Colour Naming. Furthermore, MDD patients performed significantly worse than the control group on three out of seven of the cognitively effortful measures; namely Inhibition, Inhibition/Switching and Category Fluency.
  
  
  CONCLUSIONS
  We could not find consistent support for the cognitive effort hypothesis in the present study. However, the results indicate that depressed patients have a specific impairment within the Executive Function domain affecting Inhibition, Inhibition/Switching and Category Fluency.
authors.affiliation: Department of Biological and Medical Psychology, University of Bergen, Norway. Aasa.hammar@psybp.uib.no
authors.forename: Asa
authors.initials: A
authors.lastname: Hammar
authors.forename: Mari
authors.initials: M
authors.lastname: Strand
authors.forename: Guro
authors.initials: G
authors.lastname: Ardal
authors.forename: Marit
authors.initials: M
authors.lastname: Schmid
authors.forename: Anders
authors.initials: A
authors.lastname: Lund
authors.forename: Rebecca
authors.initials: R
authors.lastname: Elliott
mesh_terms: D000328:Adult; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004522:Educational Status; D056344:Executive Function; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008570:Memory, Short-Term; D016743:Mental Competency / Q000523:psychology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales