Addition of Vision Impairment to a Life-Course Model of Potentially Modifiable Dementia Risk Factors in the US
Abstract
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.
Study interpretation
As dementia drugs continue to prove ineffective during clinical trials, public health experts and researchers call to switch the approach to tackling dementia to a more preventive one. There are currently 12 modifiable risk factors for preventing dementia. These include:
- High blood pressure
- Lower education levels
- Impaired hearing
- Smoking
- Obesity
- Depression
- Physical inactivity
- Diabetes
- Low levels of social contact
- Excessive alcohol consumption
- Traumatic brain injuries
- Air pollution
The Lancet Commission on Dementia Prevention, Intervention and Care began the modifiable risk factor movement in 2017. A panel of doctors, epidemiologists, and public health experts reviewed hundreds of scientific studies to find the first 9 modifiable risk factors in the above list. The last three were added by the commission in 2020.
The commission calculated that 40% of dementia cases worldwide could theoretically be prevented or delayed if those factors were eliminated.
The above study found that these 12 modifiable risk factors were associated with an estimated 62.4% of dementia cases in the United States. The study further finds that vision impairment can also lead to dementia and suggests adding it as a risk factor to the list.
The Centers for Disease Control have adopted this approach of improving modifiable risk factors to tackle dementia. Some of these risk factors can be quick and easy fixes that would have lasting impacts. While others could be harder to tackle overall the payoffs are massive since treating and caring for dementia is very expensive. So, even pushing back the disease has a high impact on families.
We’re not talking about expensive interventions or fancy surgery or seeing specialists who are hours away,” said Dr. Joshua Ehrlich, an ophthalmologist and population health researcher at the University of Michigan and the study’s lead author, as per The New York Times.
These are things people can do in the communities where they live.”
Dr. Joshua Ehrlich, an ophthalmologist and population health researcher at the University of Michigan
Sources:
JAMA Network: “Addition of Vision Impairment to a Life-Course Model of Potentially Modifiable Dementia Risk Factors in the US“
The New York Times: “New Dementia Prevention Method May Be Behavioral, Not Prescribed“