- The brain changes with age but dementia is not a natural result of ageing.
- Variety in life, in social contacts and in leisure pursuits all seem to be significant protective factors.
- Level of education seems to have some bearing on risk of developing dementia.
- Brain plasticity and cognitive reserve may also influence risk.
This chapter looks at some very basic factors that research indicates may be associated with an increased risk of dementia. The first of these is age. We hear so often that cases of dementia are increasing because we are living longer, but is this really the case?
Age and dementia
Whilst there are some quite striking examples of younger people developing dementia (particularly ‘familial’ dementia, which is examined on page124), the most prominent ‘risk factor’ for developing the condition is indeed age. Dementia is a disease of older people. However, it is not an inevitable result of ageing. Many older people have excellent cognition, even taking into account the natural slowing down of life in general as we get older.
A person’s risk of developing dementia rises from one in 14 over the age of 65, to one in six over the age of 80. That is, one in 14 people over the age of 65 have dementia.1 Also, that five in six people over the age of 80 do not. What makes the difference between those who do have dementia symptoms and those who don’t? Let’s examine some of the factors that seem to play a part alongside age. Strikingly, research shows that personality and social factors are significant in this respect.
Personality, social factors and dementia
The Nun Study
David Snowdon, a US-based neurologist, has studied ageing and dementia in a population of 678 nuns. ‘The Nun study’, as it is known, is a most useful source for researchers because it is a longitudinal study (that’s a study that follows a group over a long period of time) of ageing and Alzheimer’s disease, which began in 1986 as a pilot study on ageing and disability. It started out using data collected from the older School Sisters of Notre Dame living in Mankato, Minnesota, but later expanded to include older Notre Dame Sisters living in the midwestern, eastern and southern regions of the United States. Participants in the Nun Study include women representing a wide range of functioning and health. Some Sisters are in their 90s; others may be in their 70s. Some are highly functional, with full-time jobs; others are severely disabled, unable to communicate, possibly even bed-bound.
Each of the 678 participants in the Nun Study agreed to participate in annual assessments of their cognitive and physical function. The assessments have included medical examinations and giving blood samples, and many of the nuns agreed to donate their brains after death for research. This means that the Nun Study represents the largest brain-donor population in the world. In addition, the Sisters have given investigators full access to their convent and medical records.
The study has found that traits in early, mid an