title: Central auditory processing in aging: the dichotic listening paradigm.
abstract: OBJECTIVE
  Aging is associated with cognitive changing. Central auditory processing dysfunction may explain some understanding difficulties in elderly. It may be evaluated with the dichotic listening (DL) test, a widely-used experimental paradigm for studying inter-hemispheric interactions and attentional processes. This study examines central auditory language processing with a dichotic listening task in right-handed old subjects according to their age.
  
  
  METHODS
  Cross sectional-study.
  
  
  METHODS
  memory clinic and geriatric unit.
  
  
  METHODS
  Adult group (Ad) consisted in 26 subjects (21 women and 5 men) aged 50-69 years and an old adults group (Old-Ad) consisted in 20 subjects (19 women and 1 man) aged 70 to 89 years.
  
  
  METHODS
  DL consisted in a free-recall word task and a digit forced-attention task (forced-right: FR and forced-left: FL) in order to study central auditory language processing. In addition, we used neuropsychological tests to study executive functions and cognitive control, sustained by the prefrontal cortex.
  
  
  RESULTS
  In the free recall condition, we confirmed the classic right ear advantage (REA) in both groups, particularly in older subjects. In the forced condition, we observed an ear advantage with a change in ear asymmetry as a consequence of instruction: REA in FR and a left-ear advantage (LEA) in FL. We compared contaminations by the contra-lateral inattentive ear: reports of the left ear (LE) in the FR condition and reports of the right ear (RE) in the FL condition. Contaminations by the RE in the FL condition were more pronounced in Old-Ad suggesting difficulties in competition between the natural tendency for the RE and the instruction. In the Old-Ad group, the correlation between the RE score in FL and TMT B-A/A suggests an impairment in mental flexibility.
  
  
  CONCLUSIONS
  DL may be helpful to study central auditory dysfunction in aging. Our results suggest difficulties in attentional control and executive functions. Central auditory dysfunction should be evaluated in elderly because it potentially contributes to difficulty of hearing in noisy environment with consequences in the rehabilitation of presbyacousic subjects. More studies are needed to investigate the predictive value of DL as a marker of cognitive decline, particularly executive functions.
authors.affiliation: CMRR région Centre et Médecine Interne Gériatrique, CHRU de Tours, Tours, France. hommet@med.univ-tours.fr
authors.forename: C
authors.initials: C
authors.lastname: Hommet
authors.forename: K
authors.initials: K
authors.lastname: Mondon
authors.forename: G
authors.initials: G
authors.lastname: Berrut
authors.forename: Y
authors.initials: Y
authors.lastname: Gouyer
authors.forename: M
authors.initials: M
authors.lastname: Isingrini
authors.forename: T
authors.initials: T
authors.lastname: Constans
authors.forename: C
authors.initials: C
authors.lastname: Belzung
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001288:Attention; D001307:Auditory Perception; D003072:Cognition Disorders / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D004007:Dichotic Listening Tests / Q000379:methods; D004423:Ear; D056344:Executive Function; D005260:Female; D007839:Functional Laterality; D015577:Geriatric Assessment / Q000379:methods*; D006311:Hearing Disorders / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex; D000091402:Prohibitins