Aims: Observational epidemiology suggests that 8% of global dementia cases might be attributable to hearing loss. Only one trial has been reported with negative results. We aimed to determine if the early clinical remediation of hearing impairment reduces the rate of cognitive decline among older adults at risk of dementia.
Methods: The HearCog trial is a 24-month, randomised, controlled clinical trial that investigated whether hearing loss intervention with hearing aids could delay or arrest cognitive decline. We randomised 211 hearing-impaired people over the age of 70 years, with mild cognitive impairment (Montreal Cognitive Assessment for the Hearing Impaired (HI-MOCA) >18 and <26), to an experimental or a delayed-control group to determine whether hearing aid use reduces the rate of cognitive decline over 24 months. Secondary aims were to investigate whether correcting hearing loss had a beneficial impact on memory, executive functions, anxiety and depressive symptoms, quality of life and physical health over 24 months. The difference between intervention and control groups for cognitive and psychosocial measures was estimated using generalised linear mixed modelling (GLMM).
Results: No significant difference was observed between the intervention and control groups for primary cognitive outcome measures. For the primary cognitive outcome HI-MOCA at 12 months, treatment effect was 0.5, 95%CI -0·4 to 1·3; at 24 months the treatment effect 0·2, 95%CI -0·7 to 1·1.
Conclusion: The use of a hearing aid for 24 months did not significantly benefit cognitive outcomes in older adults at risk of dementia.