title: Olfactory dysfunction, gambling task performance and intracranial lesions after traumatic brain injury.
abstract: OBJECTIVE
  To estimate the incidence of olfactory dysfunction across traumatic brain injury (TBI) severity and decision-making deficits with regard to intracranial lesions' location and laterality.
  
  
  METHODS
  A 1-year prospective study including 115 participants (16-55 years) with mild, moderate, and severe TBI. The Brief Smell Identification Test was used 3 months postinjury with a follow-up testing of olfactory dysfunction at 1 year. The Iowa Gambling Task (IGT) and 3 tasks of the Delis-Kaplan Executive Function System were administered 3-months postinjury. MRI was performed 1-year postinjury and TBI severity groups were then divided with respect to frontal, fronto-temporal, diffuse, and no lesions.
  
  
  RESULTS
  The incidence of olfactory dysfunction was estimated to be 22.3% at 3 months and 13.5% at 1 year. No significant differences were found on olfactory dysfunction across TBI severity at either check. Anosmia was identified in 10% with severe TBI and 3% with mild TBI. Olfactory dysfunction was associated with verbal fluency tasks. Repeated-measures analysis of variance revealed no significant effect over blocks on IGT, and no main group or interaction effects regarding TBI severity, lesions' location, or laterality. IGT performance at 3-months postinjury was deficient in 83% of persons with intracranial lesions and 71% of those without lesions.
  
  
  CONCLUSIONS
  Olfactory dysfunction is independent of TBI severity, showing improvements in one third of cases from 3- to 12-months postinjury. However, anosmia was related to TBI severity. There is evidence for marked decision-making deficits after TBI, all subgroups performed similarly and failed to develop an advantageous strategy over time.
authors.affiliation: Sunnaas Rehabilitation Hospital, Sunnaas Rehabilitation Hospital, 1450 Nesoddtangen, Norway. solrun.sigurdardottir@sunnaas.no
authors.forename: Solrun
authors.initials: S
authors.lastname: Sigurdardottir
authors.forename: Tone
authors.initials: T
authors.lastname: Jerstad
authors.forename: Nada
authors.initials: N
authors.lastname: Andelic
authors.forename: Cecilie
authors.initials: C
authors.lastname: Roe
authors.forename: Anne-Kristine
authors.initials: AK
authors.lastname: Schanke
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000150:complications / Q000473:pathology / Q000523:psychology; D003072:Cognition Disorders / Q000209:etiology*; D056344:Executive Function / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D005715:Gambling / Q000523:psychology*; D005717:Games, Experimental; D015600:Glasgow Coma Scale; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D000857:Olfaction Disorders / Q000209:etiology*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D055815:Young Adult