This chapter is the first of two focusing on dementia. Chapter 8 reviews four sets of intersecting material: inequality-related risks relating to dementia that are a product of the life course and later life itself; mental health problems among people living with dementia; what we know about the mental health, well-being and quality of life of people living with dementia; and evidence relating to how we understand and measure quality of life and well-being in this growing population. Information about the prevalence of dementia and the different types is covered in Chapter 1.

Research evidence relating to dementia tends to be of two kinds: it either relates to a specific type(s) of dementia or to the broader category of ‘dementia’. Where I discuss the latter, more specific evidence does not exist.

Dementia: life course and age-related risks and inequalities

Life course-related risks and inequalities

There is growing evidence of links between a number of life course inequalities and increased incidence of dementia. Low socio-economic status (SES) across the whole life course and lower levels of education in early life have been consistently identified as risks for developing dementia, particularly Alzheimer's disease (Fratiglioni and Qiu, 2013; Livingstone et al, 2017). Specific issues arising from low SES that appear relevant include poor nutrition, inadequate housing, higher levels of alcohol and tobacco consumption, lower levels of exercise and chronic stress; evidence relating to smoking is especially strong (Zhong et al, 2015) (see Chapter 3 regarding links between damaging health-related behaviours and low SES). In part this link can be explained by heightened risk of cardiovascular disease (CVD) which plays an obvious causal role in the development of vascular dementia. The risk factors for CVD – obesity, hypertension and high cholesterol – are life course-related and linked, via the factors noted earlier, to low SES and disadvantage. That recent research also suggests that CVD predisposes people to Alzheimer's disease strengthens and amplifies these links (Alzheimer's Society, 2007). Another health-related risk factor for dementia is diabetes, a condition that has substantially increased in recent years (Azad et al, 2007).