Sensory impairment and dementia risk among older adults in rural South Africa

Abstract

Introduction: South Africa faces growing dementia challenges, worsened by limited medical resources and low education. Modifiable risk factors like hearing and vision impairments remain understudied despite their high prevalence.

Methods: We analyzed data from 567 participants in a rural South African cohort to examine the associations between vision and hearing impairment, and dementia outcomes. Multinomial logistic regression assessed associations between sensory impairments (distance vision, near vision, hearing) and mild cognitive impairment (MCI) or dementia. Linear regression examined sensory impairment and predicted dementia probability score 2 years later.

Results: Half of the participants were over 70, with no formal education. Sensory impairments were common, especially in dementia cases. Distance vision impairment was linked to both MCI and dementia, while near vision and hearing impairments were associated with dementia. Hearing impairment also predicted higher dementia probability after 2 years.

Discussion: Addressing sensory impairments is key to dementia prevention in rural South Africa.

Highlights: Among rural older South Africans, 65% had near vision impairment and 47% had hearing impairment. Distance or near vision and hearing impairments are linked to an increased risk of dementia. Distance vision impairment is also associated with a higher risk of mild cognitive impairment (MCI). Dementia risk was seven times higher with distance vision, near vision and hearing impairment. Hearing impairment increased the probability of dementia 2 years later in initially non-demented individuals.

Keywords: dementia; distance vision; hearing; near vision; rural South Africa; sensory impairment.

FIGURE 1

Study sample flow chart.

FIGURE 2

Average predicted probability of dementia by different types of sensory impairment. Note: Error bars represent 95% confidence intervals. Results were derived from Model 3 in Table 2 that compared relative risks of dementia against normal cognitive function. In addition to vision and hearing measurement, the model adjusted sex, age category, presence of cataracts, glasses use, education level, household wealth, smoking status, diabetes, hypertension, heart disease, stroke, and depressive symptoms.