The association between dual sensory impairment and dementia: A systematic review and meta-analysis

BACKGROUND: Sensory impairments have been linked to dementia. However, the impact of dual sensory impairment (DSI), combining both vision impairment and hearing impairment, on dementia has shown inconsistent results. OBJECTIVE: To systematically review the evidence on the association DSI and dementia. METHODS: A systematic literature search was conducted using MEDLINE, EMBASE, and the Cochrane Library databases. Included studies were prospective or retrospective cohort studies and a case-control study. The primary outcome was the onset of dementia or its various subtypes, including Alzheimer's disease (AD) and vascular dementia (VaD). Effect sizes, including hazard ratios (HRs), were pooled through a random-effects model. RESULTS: A total of 11 observational studies with 346,659 participants were included. DSI was significantly associated with the incidence of dementia compared to no sensory impairment (9 studies; HR: 1.46; 95% confidence interval [CI]: 1.29-1.65). Among subtypes of dementia, DSI was associated with AD onset (4 studies; HR: 2.07; 95% CI: 1.45-2.94); however, this association was not found in VaD (2 studies; HR: 1.65; 95% CI: 0.96-2.85). CONCLUSIONS: These findings suggest that DSI is significantly associated with an increased risk of dementia. Further research is required to identify preventive strategies to decrease the incidence of dementia in individuals with sensory impairment.