AUTHOR=Yang Zhizhong , Ni Jingnian , Teng Yuou , Su Mingwan , Wei Mingqing , Li Ting , Fan Dongsheng , Lu Tao , Xie Hengge , Zhang Wei , Shi Jing , Tian Jinzhou 

TITLE=Effect of hearing aids on cognitive functions in middle-aged and older adults with hearing loss: A systematic review and meta-analysis

JOURNAL=Frontiers in Aging Neuroscience

VOLUME=Volume 14 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2022.1017882

DOI=10.3389/fnagi.2022.1017882

ISSN=1663-4365

ABSTRACT=Objective: The study aimed to examine the effects of hearing aids on cognitive function in middle-aged and older adults with hearing loss.
Data sources and study selection: PubMed, Cochrane Library, and EMBASE before 30 March 2022 were searched. Randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSIs) were included. No restriction was set on types, severity, or the time onset of hearing impairment, nor on cognitive or psychiatric statuses. 
Data extraction and synthesis: Two independent reviewers extracted data and assessed the study quality of RCTs. Cognitive function outcomes were descriptively summarized and converted to standardized mean difference (SMD) in meta-analysis. Meta-analysis was conducted in RCTs. Sub-group analyses were conducted by cognitive statuses, psychiatric disorders, and cognitive domains. 
Results: Fifteen studies met the inclusion criteria, including five RCTs (n = 339) and ten NRSIs (n = 507). Groups were classified into subjects without dementia or with normal global cognition, subjects with AD or dementia, and subjects with depressive symptoms. For subjects without dementia, improvements were found in global cognition, executive function, and episodic memory. For subjects with depressive symptoms, improvements were found in immediate memory, global cognition, and executive function. No improvement was found in AD or dementia subjects. Four RCTs were included in the meta-analysis. No significant effect was found in subjects without dementia (SMD = 0.11, 95% confidence interval [CI]: −0.15–0.37) and AD patients for global cognition (SMD = −0.19, 95% CI: −0.65–0.28). For subjects without dementia, no significant effect was found in language (SMD = 0.14, 95% CI: −0.30–0.59) or general executive function (SMD = −0.04, 95% CI: −0.46–0.38). Further subgroup analysis found no significant effect in executive function (SMD = −0.27, 95% CI: −0.72–0.18) or processing speed (SMD = −0.02, 95% CI: −0.49–0.44).
Conclusion: Hearing aids might improve cognitive performance in domains, such as executive function, in subjects without dementia. The effects in subjects with depressive symptoms remained unclear. No improvement was found in subjects with AD or dementia. Long-term RCTs and well-matched comparison-group studies with large sample sizes are warranted.