The combined effects of visual impairment, hearing loss, and olfactory dysfunction on cognitive impairment: An individually matched case–control study

The combined effects of visual impairment, hearing loss, and olfactory dysfunction on cognitive impairment remain unclear. We conducted a case-control study with 25,432 adults aged 60 years or older. We used multiple logistic regression to analyze the effects of combined visual impairment, hearing loss, and olfactory dysfunction on cognitive impairment, while controlling for confounding factors. Single or combined visual impairment, hearing loss, and olfactory dysfunction negatively influenced cognitive impairment. Olfactory dysfunction had the greatest impact on dementia (odds ratio [OR] 2.37, 95% confidence interval 95% [CI] 2.01-2.79). For patients with combined sensory dysfunction, visual and olfactory dysfunction combined had the greatest impact on dementia (OR 6.50, 95% CI 3.78-11.20). Visual impairment, hearing loss, and olfactory dysfunction, as noninvasive functional biomarkers, provide a viable approach for the early detection and prevention of cognitive impairment, and can be utilized as effective means of early diagnosis and pre-intervention of dementia. Olfactory dysfunction has a greater impact on cognition than visual impairment and hearing loss. The interaction of two sensory dysfunctions has a greater effect on cognition than one sensory dysfunction alone. Sensory dysfunction provides a viable approach for the early detection and prevention of cognitive impairment.