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

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 model of dementia risk factors, developed by the Lancet Commission, 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 (11 of those included in the Lancet Commission's life-course model) 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, such as the Lancet Commission's, 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.

Automated summary

Dementia prevention is important due to its significant impact on individuals and society. Vision impairment has been identified as a risk factor for cognitive decline and dementia. However, it has not been included in the dominant dementia risk factor model, potentially leading to bias in public health policy and research priorities.