The role of psychosocial risk factors in the development of late onset, severe dementia was examined in a longitudinal prospective study of a representative sample followed from 70 to 79 years of age. Subjects with any signs of dementia at the age of 70 were excluded. Eighteen risk factors occurring before the age of 70 were studied, five from childhood and youth, five from adult age and eight from the age of 65-70. Thirty-eight subjects developed dementia, and they were compared to the other 326 subjects. Death of a parent before the age of 16, previous arduous manual work, physical illness in the spouse after the age of 65 and serious illness in a child after the age of 65 made independent contributions to the prediction of dementia. There was a dose-response relationship: in subjects without exposure 3% developed dementia, in subjects with exposure to one or two risk factors 8% developed dementia, and in subjects with exposure to three of more risk factors 20% developed dementia. The association with psychosocial risk factors was similar in the aetiological subgroups Alzheimer's disease and vascular dementia. There was no association with education or alcohol abuse. We suggest that the associations between psychosocial risk factors and dementia are due to the effects of stress, but other interpretations are also possible. The results should be regarded as preliminary until confirmed by others.
KEY wotlosdementia: Alzheimer's disease: vascular dementia; risk factor; life events; stress; childhood bereavement; epidemiology
The most common dementias in old age are Alzheimer's disease (SDAT) and dementias due to vascular causes, often subsumed under the term multi-infarct dementia (MID).
Well-established risk factors for SDAT are advanced age and Alzheimer's disease (DAT) in a first-degree relative. There is some evidence that higher age of the mother at the birth of the subject (Amaducci and Lippi, 1992) and low education (Katzman, 1993) are both important. Risk factors for MID include advanced age, stroke, hypertension and heart disease (Skoog, 1994).
Psychosocial risk factors may also be worth considering. A causal link might be that such risk factors cause stress reactions, as recent studies in animals have established associations between stress and early mental ageing. In rats, stress