The Lancet Commission Identifies Additional Dementia Risk Factors

In a report published July 30, 2020, the Lancet Commission added 3 new risk factors for dementia based on newer, convincing evidence.¹ Combined with 9 lifestyle risk factors outlined in its 2017 Lancet Commission on dementia prevention, intervention, and care life-course model, the Commission reports that modifying these 12 risk factors might prevent or delay up to 40% of dementias worldwide.

Approximately 50 million people worldwide currently live with dementia, and this number is projected to triple within the next 30 years. “The potential for prevention is high and might be higher in low-income and middle-income countries (LMIC) where more dementias occur,” the report states.

The new dementia risk factors include excessive alcohol consumption, traumatic brain injury (TBI), and air pollution. Previously identified risk factors include less education, hypertension, hearing impairment, smoking, obesity, depression, physical inactivity, diabetes, and limited social contact.

To support TBI as a risk factor for dementia, the Commission cited a Danish cohort study that followed approximately 3 million people age ≥50 years for a mean of 10 years. The investigators reported that TBI was associated with increased risk for dementia (hazard ratio [HR], 1.24; 95% CI, 1.21-1.27) and Alzheimer disease (HR, 1.16; 95% CI, 1.12-1.22).²

Increased alcohol consumption is associated with brain changes, cognitive impairment, and dementia. However, the Commission recognizes that sociocultural and other health-related factors associated with alcohol use make it “particularly challenging to understand the evidence base” supporting the relationship between alcohol and cognition/dementia.

Findings from studies in animal models suggest that airborne particulate pollutants accelerate the onset of dementia. Pollution caused by traffic exhaust and wood burning was cited as contributing to an increased risk for dementia. A US study found that the burden of dementia from pollution was especially high in Black and African American individuals and socioeconomically disadvantaged communities.³

Dementia Risk by Life Stage

The Commission updated its life course model, which outlines interventions that may reduce the risk of dementia in early (aged <45 years; education), mid (aged 45-65 years; hearing loss, TBI, hypertension, increased alcohol use, obesity), and later life (aged ≥65 years; smoking, depression, social isolation, physical inactivity, diabetes, air pollution). Regardless of age, communities can reduce individuals’ dementia risk by tackling inequality, particularly in Black, Asian, and minority ethnic groups and vulnerable populations.

Suggestions from the Commission to modify risk factors for dementia include making exercise the norm rather than the exception; promoting better nutrition; and reducing noise and air pollution. For individuals with dementia, the Committee recommends the provision of care that addresses both physical and mental health, social care, and support. Interventions for caregivers are also advised to improve quality of life and symptoms of anxiety and depression.

References

1. Livingston G, Huntley J, Sommerlad A, et al. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet. Published online July 30, 2020. doi:10.1016/S0140-6736(20)30367-6

2. Fann JR, Ribe AR, Pedersen HS, et al. Long-term risk of dementia among people with traumatic brain injury in Denmark: a population-based observational cohort study. Lancet Psychiatry. 2018;5(5):424-231. doi:10.1016/S2215-0366(18)30065-8

3. Bowe B, Xie Y, Yan Y, Al-Aly Z. Burden of cause-specific mortality associated with PM_2.5 air pollution in the United States. JAMA Netw Open. 2019;2(11): e1915834. doi:10.1001/jamanetworkopen.2019.15834