Addition of Vision Impairment to a Life-Course Model of Potentially Modifiable Dementia Risk Factors in the US

Question  Should vision impairment be included in a life-course model of potentially modifiable dementia risk factors?

Findings  In this cross-sectional study of 2018 data from the Health and Retirement Study on 16 690 US adults aged 50 years and older, an estimated 1.8% of dementia cases in the US (more than 100 000 prevalent cases) were associated with vision impairment.

Meaning  These results suggest that vision impairment should be included life-course models of potentially modifiable dementia risk factors.

Importance  Dementia prevention is a high priority, given the large impact of dementia on the well-being of individuals and society. The number of older adults with dementia in the US and globally is projected to increase as a result of population aging and growth. Thus, it is vital to identify potentially modifiable dementia risk factors. Vision impairment has been identified as a risk factor for accelerated cognitive decline and incident dementia. An estimated 90% of vision impairment is preventable or has yet to be treated. Nevertheless, vision impairment has not been included in the dominant life-course models of dementia risk factors used to shape public health policy and research priorities.

Objective  To strengthen an existing model of potentially modifiable dementia risk factors through the inclusion of vision impairment and to estimate the contributions of those risk factors in the US population.

Design, Setting, and Participants  Population-based, cross-sectional study using data from the 2018 round of the Health and Retirement Study. Analyses were conducted from March 11 through September 24, 2021. The study population was a probability sample of US adults aged 50 years and older.

Exposures  Potentially modifiable dementia risk factors, including vision impairment.

Main Outcomes and Measures  The estimated population attributable fractions (PAFs) of dementia associated with vision impairment and other dementia risk factors were calculated. The PAF represents the number of cases of dementia that would potentially be prevented if a risk factor were eliminated.

Results  The probability sample from the Health and Retirement Study included 16 690 participants (weighted demographic characteristics: 54.0% female, 52.0% age ≥65, 10.6% Black, 80% White, and 9.2% identified as other [including American Indian or Alaska Native, Asian, and Hawiian Native or Pacific Islander, although specific data were not available]). The 12 dementia risk factors in the PAF model were associated with an estimated 62.4% of dementia cases in the US. The risk factor with the highest weighted PAF for dementia was hypertension (12.4%). The PAF of vision impairment was 1.8%, suggesting that more than 100 000 prevalent dementia cases in the US could potentially have been prevented through healthy vision.

Conclusions and Relevance  Existing life-course models of potentially modifiable dementia risk factors may consider including vision impairment. Since a large majority of vision impairment can be treated with cost-effective but underused interventions, this may represent a viable target for future interventional research that aims to slow cognitive decline and prevent incident dementia.