Author(s): Merten N, Fischer ME, Tweed TS, Breteler MMB, Cruickshanks KJ. Associations of Hearing Sensitivity, Higher-order Auditory Processing, and Cognition over Time in Middle-aged Adults. J Gerontol A Biol Sci Med Sci. 2019 Aug 16. pii: glz189. doi: 10.1093/gerona/glz189. [Epub ahead of print]
Journal: The Journals Of Gerontology. Series A, Biological Sciences And Medical Sciences, Aug 2019
BACKGROUND Age-related hearing loss (impairment in hearing sensitivity and/or higher-order auditory processing) and cognitive decline are common co-occurring impairments in the elderly. Their relation in the process of aging remains insufficiently understood. We aim to assess the temporal relations of decline in hearing sensitivity, higher-order auditory processing, and cognition in middle-aged adults.
METHODS This study included 1274 Beaver Dam Offspring Study participants who participated in three examinations (baseline, 5-year, and 10-year follow-up). We assessed hearing sensitivity through pure-tone audiometry (PTA, averaged thresholds of 0.5,1,2,4 kHz of the better ear), higher-order auditory processing as word recognition in competing message (WRCM) using the Northwestern University 6 word list in the better ear, and cognition through trail-making test performance (TMT). Linear mixed-effects models and linear regression models were used to determine associations over time and to what extent these measures influence each other over time.
RESULTS The longitudinal decline between all functions was associated with the strongest relations between PTA and WRCM. The effect of baseline PTA on WRCM ten years later (standardized ß=-.30) was almost twice as big as the effect of baseline WRCM on PTA ten years later (standardized ß=-.18). The effect of baseline WRCM on TMT ten years later and vice versa were small (standardized ß=-.05). No directional relationship between PTA and TMT was identified (standardized ß≤.02).
CONCLUSIONS While hearing sensitivity might affect higher-order auditory processing, associations between hearing and cognition appear bidirectional and weak in midlife. We need to be cautious before inferring causal effects of hearing on cognition.