Table 1 Risk and protective factors for dementia and Alzheimer's disease

Genetic

Psychosocial factors

Increased

   ApoE ε4

   High education and socioeconomic status

1. Genetic and environmental factors in mid-life

   Familial aggregation

   ApoE ε4 magnifies the effect of high alcohol intake, smoking, physical inactivity, and high intake of saturated fat.

   High work complexity

Vascular

   Rich social network and social engagement

2. Vascular factors in mid-life

   Cerebrovascular lesions

   Hypertension, obesity, hypercholesterolemia, and physical inactivity have an additive effect when they co-occur.

   Mentally stimulating activity

   Cardiovascular diseases

3. Vascular factors/diseases in late life

   Diabetes mellitus and prediabetes

Lifestyle

   Higher risk in individuals with brain hypoperfusion profile: chronic heart failure, low pulse pressure, and low diastolic pressure

Physical activity

   Higher risk in individuals with atherosclerosis profile: high systolic pressure, diabetes mellitus or prediabetes, and stroke

Positive association in mid-life but negative association in late life

Diet

Decreased

   Hypertension

   Mediterranean diet

1. Genetic and environmental factors in mid-life

   High BMI (excessive weight and obesity)

   Polyunsaturated and fish-related fats

   High education reduces the negative effect of ApoE ε4.

   Physical activity counteracts the risk due to ApoE ε4.

   High serum cholesterol

   Vitamins B₆ and B₁₂ and folate Antioxidant vitamins (C and E)

2. Environmental factors in mid-life

   High work complexity modulates the increased dementia risk due to low education.

Lifestyle

   Smoking

   High alcohol intake

Diet

   Saturated fats

   Homocysteine

Others

   Depression