Relationship between hearing loss, cognitive impairment, and dementia; meta-analysis of cohort studies in which the exposure factor is hearing loss measured by audiometry

INTRODUCTION-OBJECTIVES: There is a probable relationship between hearing loss and cognitive decline and dementia: patients with hearing loss appear to develop cognitive difficulties earlier and more frequently. However, the relationship is not completely clear. A meta-analysis of high-quality studies is needed to clarify the nature of this relationship. MATERIALS AND METHODS: Meta-analysis of cohort studies in which the exposure factor is hearing loss, necessarily measured with pure-tone audiometry, and the outcome is the progression of cognitive decline measured with validated scales or the onset of dementia. The inclusion period for the studies was 2019-2023. RESULTS: Of the 5349 articles identified, 11 cohort studies were included in the systematic review; and 8 in the meta-analysis. In those where the outcome was dementia (expressed as Hazard Ratio [HR]), a statistically significant relationship was found, with an HR of 1.32 (1.30-1.34), with low heterogeneity and a low risk of publication bias. In those where the outcome was expressed as linear regression (beta), no statistically significant results were found. CONCLUSIONS: There appears to be a relationship between hearing loss and cognitive impairment/dementia. Other forms of hearing loss (such as central hearing loss) need to be evaluated to fully assess the effect and implications of this relationship.