Greatest Risk Factors for Dementia
The greatest risk factors for dementia include age, hearing loss, hypertension, obesity, smoking, depression, physical inactivity, social isolation, and diabetes, with age being the strongest and most well-established risk factor. 1, 2
Age-Related Risk
- Dementia prevalence increases dramatically with age:
- 5% in persons aged 71-79 years
- 24% in persons aged 80-89 years
- 37% in persons older than 90 years
- Risk approximately doubles every 5 years after age 65 2
Mid-Life Risk Factors
According to the Alzheimer's Association guidelines, three key mid-life risk factors have been identified 1:
- Hearing loss
- Hypertension
- Obesity
These factors are particularly impactful when present during middle age (45-65 years) and have stronger associations with later dementia development than when they develop in later life 1, 3.
Later-Life Risk Factors
Five additional modifiable risk factors in later life include 1:
- Smoking
- Depression
- Physical inactivity (most prevalent at 60.3% in some populations 4)
- Social isolation
- Diabetes
Genetic and Non-Modifiable Risk Factors
- Family history of Alzheimer's disease
- Apolipoprotein ε4 genotype
- Down syndrome 1
- Traumatic brain injury 2
Demographic Risk Factors
- Gender: Women have higher prevalence (16% vs. 11% in men over age 71), primarily due to longer life expectancy 2
- Race/ethnicity: Higher prevalence in Black Americans (21.3%) compared to White Americans (11.2%), and Hispanic Americans have approximately 1.5 times higher prevalence of Alzheimer's disease compared to White Americans 2
- Socioeconomic status: Low SES is strongly associated with increased dementia risk factors (β = 0.80) 5
Cardiovascular Risk Factors
Vascular risk factors significantly contribute to dementia risk 3:
- Hypertension (particularly in midlife)
- Diabetes
- Hypercholesterolemia
- Heart disease
- Obesity
Lifestyle Factors
- Low educational level 1, 6
- Physical inactivity 1, 4
- Poor diet (irregular consumption of fruits and vegetables) 4
- Smoking 1
- Excessive alcohol consumption 6
- Cognitive inactivity 1
Risk Reduction Potential
Estimates suggest that addressing modifiable risk factors could reduce dementia risk by approximately 20% 1. The LIBRA (LIfestyle for BRAin health) index has been validated as a tool to identify individuals for primary prevention interventions, particularly effective in midlife (55-69 years) and late life (70-79 years), but not in the oldest-old (80+ years) 7.
Clinical Implications
- Primary care clinicians should perform personalized assessment of dementia risk factors in middle-aged and older adults 1
- Counseling on "brain-healthy behaviors" should focus on the American Heart Association's Life's Simple 7 1:
- Non-smoking status
- Physical activity at goal levels
- BMI < 25 kg/m²
- Healthy diet
- Blood pressure < 120/80 mm Hg
- Total cholesterol < 200 mg/dL
- Fasting blood glucose < 100 mg/dL
Pitfalls and Caveats
- Current prevalence figures likely underestimate the true burden of dementia due to high rates of undiagnosed cases 2
- The effect of risk factors may vary by age of exposure, with midlife exposure to hypertension, obesity, and dyslipidemia having stronger associations with dementia than late-life exposure 3
- In patients with existing cognitive impairment, diabetes treatment plans should be simplified to minimize hypoglycemia risk, as severe hypoglycemia is associated with reduced cognitive function 1