Lifelong learning and mentally stimulating activities may build “cognitive reserve,” which helps the brain compensate for age-related or pathological changes. Higher educational attainment, complex occupations, reading, puzzles, and learning new skills have all been associated with delayed cognitive decline (Stern, 2012). The idea is not simply staying busy, but consistently challenging the brain in novel ways. (Stern, 2012; Livingston et al., 2020)

Regular physical activity - particularly aerobic exercise - improves cerebral blood flow, reduces inflammation, and supports hippocampal health (a region critical for memory). Observational and interventional studies show that physically active individuals have lower dementia risk compared to sedentary peers (Barnes & Yaffe, 2011).

Exercise also improves vascular and metabolic health, both of which strongly influence cognitive outcomes. (Barnes & Yaffe, 2011; Livingston et al., 2020)

Dietary patterns such as the Mediterranean diet and the MIND diet (a Mediterranean-DASH hybrid) are associated with slower cognitive decline and lower Alzheimer’s incidence (Scarmeas et al., 2006).

These diets emphasize:

Olive oil

Fish

Nuts

Leafy greens

Whole grains

Limited ultra-processed foods

Metabolic conditions like obesity, insulin resistance, and type 2 diabetes are linked to increased dementia risk, particularly when present in midlife (Norton et al., 2014).

(Scarmeas et al., 2006; Norton et al., 2014; Livingston et al., 2020)

What benefits the heart also benefits the brain. Midlife hypertension, high cholesterol, smoking, and diabetes are major modifiable risk factors for dementia (Livingston et al., 2020).

Chronic vascular damage reduces blood flow to the brain and contributes to both vascular dementia and Alzheimer’s pathology. Managing blood pressure in midlife is one of the strongest protective strategies identified.

(Livingston et al., 2020; Norton et al., 2014)

Sleep plays a critical biological role in clearing beta-amyloid and tau proteins through the brain’s glymphatic system (Xie et al., 2013). Chronic sleep deprivation and untreated sleep disorders (such as sleep apnea) are associated with increased Alzheimer’s pathology.

Prioritising 7–9 hours of quality sleep may be protective over time.

(Xie et al., 2013; Livingston et al., 2020)

Social isolation and loneliness are linked to increased cognitive decline. Regular social interaction may reduce stress pathways, stimulate cognition, and support emotional resilience (Livingston et al., 2020).

Community involvement, maintaining friendships, and meaningful relationships are all associated with lower dementia risk.

(Livingston et al., 2020)

Chronic stress elevates cortisol, which can negatively impact the hippocampus over time. Depression is both a potential risk factor and an early marker of dementia (Livingston et al., 2020).

Managing mental health through therapy, stress reduction techniques, and lifestyle interventions may therefore play a role in long-term cognitive health.

(Livingston et al., 2020)

The APOE ?4 gene variant increases Alzheimer’s risk, but it does not determine outcome. Many individuals with genetic risk never develop dementia.

Research increasingly supports a gene–environment interaction model, meaning lifestyle factors such as diet, exercise, and vascular health may moderate genetic susceptibility (Jack et al., 2018).

(Jack et al., 2018; Livingston et al., 2020)

Smoking increases oxidative stress and vascular damage, both linked to dementia. Heavy alcohol consumption is also associated with higher risk, particularly when sustained over time (Livingston et al., 2020).

Avoiding smoking and limiting alcohol intake are important modifiable protective factors.

(Livingston et al., 2020)

Untreated hearing loss in midlife is one of the strongest modifiable dementia risk factors identified (Livingston et al., 2020). Proposed mechanisms include increased cognitive load, social isolation, and structural brain changes.

Hearing assessment and early use of hearing aids may help reduce this risk.

(Livingston et al., 2020; Yaffe et al., 2011)