Dementia is a condition that affects the human brain, consisting of progressive loss of cognitive functioning resulting in difficulties with memory, abstract thinking and at times, changes in personality. Approximately 10% of the population who are 65 years or older have dementia, with a further 20% having a mild cognitive impairment. Dementia, like many other diseases has certain risk factors that can determine the likelihood of being diagnosed with the disease during the lifespan. While some risk factors are uncontrollable, such as genetics, others can be controlled by lifestyle or other interventions- these are also known as modifiable risk factors. Physical inactivity is one of many modifiable risk factors for dementia, other modifiable risk factors include hypertension, smoking, social isolation, diabetes and depression.

There is strong research evidence that supports physically active people with normal cognition being less likely to develop cognitive impairments later in life, but there is also research supporting the role of physical activity in improving cognition in people who are already diagnosed with dementia or a mild cognitive impairment. Physical activity may help reduce the loss of neurons and neural connections within the brain as people age. It can reduce the decline of cognitive functioning and lessen the reduction of hippocampus volume (an important area of the brain associated with memory). Physical activity also improves the health of blood vessels supplying blood to the brain (along with the rest of the body). 

Most of the research supports completing aerobic physical activity (such as walking, swimming, jogging, cycling etc…) for the prevention of dementia. The World Health Organisation (WHO) recommends completing at least 150 minutes per week of moderate-intensity activity or 75 minutes per week of vigorous-intensity activity. It is recommended to include at least 2 sessions per week of muscle strengthening and balance/falls risk-specific exercise. The WHO suggest completing two bursts of activity (around 10 minutes per bout) each day in order to achieve their recommendations.

There are still some unknowns about the role of physical activity in preventing dementia, such as what the optimal amount of weekly physical activity is; if physical activity has different effects for women compared to men; and if the specific type of dementia matters with regard to prevention from physical activity.