Exercise and socialising can make a "big difference to an older person's health and quality of life".
This is the opinion of Michelle Mitchell, charity director at Age UK.
Ms Mitchell's comment follows a study published earlier this year which revealed that dementia affects 820,000 people in the UK.
To help these people, the campaigner for older people suggested that activities were needed to "help to alleviate feelings of isolation and loneliness which are common causes of depression in later life".
The earlier study, conducted by Alzheimer's Research Trust, also suggested that the illness was severely underfund compared to other conditions.
It claimed that dementia funding is 12 times lower than that for cancer research in the UK.
Ms Mitchell explained the additional difficulties faced by older people: "Disability, illness, problems with finances and access to transport can also lead to older people being socially excluded and feeling cut off from their family, friends and local community."