Cognitive effects of untreated unilateral and bilateral hearing loss in midlife: Preliminary evidence

Hearing loss has been identified as a modifiable risk factor for cognitive decline and dementia, although most of the evidence is derived from studies in older adults. Identifying such cognitive impairment in midlife is crucial, as it serves as a baseline for understanding changes in cognitive abilities that occur later in life. The present study aimed to compare the cognitive performance of age- and socioeconomic status-matched middle-aged adults with normal hearing and those with untreated hearing loss. This study included 48 participants aged 40-65 years, comprising 24 adults with normal hearing and 24 with untreated hearing loss. Among the latter participants, 9 had unilateral loss and 15 had bilateral loss. The cognitive evaluation involved assessing memory (forward and backward digit span and contextual memory test), attention via the Go/No-Go task, and executive function via the letter and category fluency tasks. Results showed that adults with untreated hearing loss performed significantly poorer on all the cognitive tasks compared to their normal-hearing counterparts. Large effect sizes were observed for memory tasks, the category fluency task and Go/No-Go accuracy, and a moderate effect size for the letter fluency tasks. Furthermore, multivariate linear regression analysis demonstrated that better-ear pure-tone thresholds independently predicted cognitive performance, but not age or education. These findings provide preliminary evidence on the association between untreated hearing loss and cognitive performance in middle age. However, considering the modest sample size and cross-sectional study design, longitudinal studies are needed to determine the temporal relationship between hearing loss and cognitive changes.