Background. Population-based studies suggest substantial
co-morbidity between physical illness
and depression in late-life. However, a causal relationship has not
been established. If a relationship
exists, it is important to establish which aspects of poor health determine
risk for depression, and
which factors confer vulnerability or resilience in the face of poor health.
We investigate the role of disablement, measured as impairment, disability
Methods. A prospective population-based cohort study, comprising
an index assessment and 1 year
follow-up, of all residents aged 65 years or over, of an electoral ward
in London, UK (N=889).
Results. The prevalence of SHORT-CARE pervasive depression
17·7% at index assessment.
The 1 year onset rate for pervasive depression was 12·0%, and the
1 year maintenance rate 63·2%.
There was a high mortality rate among the depressed. Disablement, particularly
handicap was the
most important predictor of the onset of depression (population attributable
fraction, 0·69). Lack
of contact with friends was a direct risk factor but also modified the
association between handicap
and depression. Marriage was protective for men, but a risk factor for
women. Maintenance of
depression was predicted by low levels of social support and social
participation, rather than by disablement.
Conclusions. It seems likely that disablement, specifically
is the chief cause of onsets of
depression in late-life. Genetic predisposition, early adversity and
serious life events may play a less
prominent role than in earlier life. Effective prevention of late-life
depression requires attention at
the structural level to the sources of handicap within communities.