Can you prevent dementia with your lifestyle?
Lifestyle does meaningfully influence your risk of dementia: one third of all cases are linked to modifiable factors such as physical activity, blood pressure and smoking. Especially if you already have an elevated risk, tackling several things at once is worthwhile.
About one third of all dementia cases are linked to modifiable risk factors such as physical inactivity, smoking and high blood pressure. That is no guarantee that you can prevent dementia, but it does mean that lifestyle genuinely matters.
The most robustly supported risk factors are high blood pressure in middle age, diabetes, depression and a low level of education. These were identified as the most reliably established associations in a large meta-analysis of hundreds of prospective studies and randomised trials. Smoking also increases the risk, but the evidence for that is somewhat less strong. These are associations, not proven causes: whether something like depression causes dementia or is rather an early symptom has not yet been established.
That lifestyle change actually helps is supported by randomised research. The FINGER trial (1,260 participants, two years) showed that a combination of improved diet, more exercise, cognitive training and control of blood pressure and blood sugar improved cognitive functioning compared with a group that received only general health advice. Two comparable large trials (MAPT and PreDIVA) found no significant effect in the group as a whole, but did find one in subgroups with an elevated risk. This suggests that this approach yields the most benefit when you already have an elevated risk.
In the very oldest individuals (above the age of eighty), observational studies show that a healthy dietary pattern, exercise and social activities protect against cognitive decline, including in people with a genetic risk. However, randomised research is almost entirely absent here, so this has not yet been established with certainty.
Lifestyle interventions are generally safe, but not without risk. In the FINGER trial, 7% of active participants reported side effects, mainly muscle pain and joint complaints, compared with 1% in the control group. That is a point of concern if you are frail or elderly. Oestrogen therapy as a preventive measure against dementia is explicitly advised against on the basis of strong evidence: it does not work. The same applies to individual nutritional supplements: the results are mixed and there is no single supplement for which the evidence is strong enough to support a concrete recommendation.
Claims are based on multiple large prospective studies, a meta-analysis of 243 prospective studies and 153 RCTs, and three large multi-domain trials (FINGER n=1260, MAPT, PreDIVA). For the very oldest individuals, the basis is 27 observational cohort studies. The evidence for individual lifestyle factors is largely observational; randomised evidence is more limited but present for multi-domain interventions.