UCSF

Background

Few studies have examined impairment in multiple senses (multisensory impairment) and risk of dementia in comparison to having a single or no sensory impairment.

Methods

We studied 1,810 black and white nondemented participants from Health, Aging, and Body Composition (Health ABC) Study aged 70-79 years at enrollment. Sensory impairment was determined at our study baseline (Year 3-5 of Health ABC) using established cut points for vision (Bailey-Lovie visual acuity and Pelli-Robson contrast sensitivity test), hearing (audiometric testing), smell (12-item Cross-Cultural Smell Identification Test), and touch (peripheral nerve function tests). Incident dementia over 10 years of follow-up was based on hospitalization records, dementia medications, or at least 1.5 SD decline in Modified Mini-Mental State Examination score (race-specific). Cox proportional hazard models with adjustment for demographics, health behaviors, and health conditions evaluated the relationship between risk of dementia and increasing number of sensory impairments.

Results

Sensory impairments were common: 28% had visual impairment, 35% had hearing loss, 22% had poor smell, 12% had touch insensitivity; 26% had more than two impairments, and 5.6% had more than three sensory impairments. Number of impairments was associated with risk of dementia in a graded fashion (p < .001). Compared to no sensory impairments, the adjusted hazard ratio was 1.49 (95% CI: 1.12, 1.98) for one sensory impairment, 1.91 (95% CI: 1.39, 2.63) for two sensory impairments, and 2.85 (95% CI: 1.88, 4.30) for more than three sensory impairments.

Conclusions

Multisensory impairment was strongly associated with increased risk of dementia. Although, the nature of this relationship needs further investigation, sensory function assessment in multiple domains may help identify patients at high risk of dementia.