Does staying socially and physically active protect against dementia?

Physical activity does appear to have a protective effect against cognitive decline and dementia. Older adults who are regularly physically active maintain their cognitive functions better. Scientists believe that exercise protects the brain through multiple pathways: it suppresses inflammation, improves blood flow, and stimulates the production of growth factors for brain cells, known as neurotrophins. A low level of activity is, in turn, identified in population studies as a risk factor for Alzheimer's disease. The evidence is convincing enough to take exercise seriously, but not strong enough to call it a guaranteed remedy.

International guidelines recommend physical activity as primary prevention of dementia, but immediately add that the underlying quality of evidence is low to very low. An important caveat: in people who already have mild cognitive impairment (MCI), meaning an early stage of memory problems, it is unclear whether increased physical activity actually slows the transition to full dementia. International experts speak of 'ongoing uncertainty' on this point.

The greatest benefit appears to come from combined approaches in which exercise, healthy nutrition, cognitive training, and social engagement are deployed together. The Finnish FINGER study, a randomised controlled trial in 60- to 77-year-olds with an elevated risk of dementia, showed that such a two-year combined programme significantly slowed cognitive decline compared with general health advice alone.

The recent American POINTER study (2111 participants, average age 68) confirmed this picture. Participants in an intensively structured programme, incorporating exercise, nutrition, cognitive activity, social engagement, and cardiovascular monitoring, improved significantly more in cognitive scores than people in a self-guided variant. Notably, the self-guided group also showed cognitive improvement, just to a lesser degree. Additional good news: serious adverse events were actually fewer in the structured group. The benefit applied both to people with a particular genetic risk (APOE ε4 carriers) and to those without.

Social engagement is cited in the literature as one of the factors that may help prevent or delay cognitive decline. The problem is that social engagement in the large trials is always combined with other lifestyle changes, making it impossible to say how much of the effect is attributable purely to social contact. Estimates from review studies suggest that lifestyle changes in a broad sense could potentially prevent or delay a third of all dementia cases worldwide, but that remains an estimate based on associative research.