Longitudinal Decline on the Dichotic Digits Test

PurposeThe dichotic digits test (DDT) is commonly administered in clinical and research settings, but it is not well understood how performance changes in aging. The purpose of this study is to determine the 5-year change on the free recall task and right ear advantage (REA) in a population-based cohort and factors associated with change.MethodParticipants in the population-based Epidemiology of Hearing Loss Study, who completed the DDT during the fourth (2009–2010) and fifth (2013–2016) examination periods were included (n= 865,Mage= 72.8 years at baseline). Free recall DDT was administered using 25 sets of triple-digit pairs presented at 70 dB HL. The REA was calculated by subtracting the score in the left ear from the score in the right ear.ResultsIn 5 years, most participants (62.4%) declined on free recall performance (mean decline = 3.0% [4.5 digits],p< .01). In age-sex–adjusted models, higher baseline scores, hearing impairment, and lower education were significantly associated with increased risk of decline. An REA at baseline (76.8%) and follow-up (77.9%) was common. Half of participants (50.6%) had a 5-year REA widening (M= 1.9% [1.4 digits],p= .01). Older age, but not hearing impairment, was associated with increased risk of REA widening.ConclusionsThe 5-year decline on free recall recognition performance was not associated with age but was associated with hearing impairment, whereas the 5-year widening of REA was associated with age but not hearing impairment. These results indicate that the REA may be a more sensitive measure of aging of the central auditory system than free recall performance.