Models of stress, vulnerability and affective disorder.

The concept of vulnerability indicates predisposition to affective disorder; characterised by greater sensitivity to stress but with no added risk in its absence. Mastery, self-esteem and attributional style may be involved but exogenous factors can also act as markers of vulnerability. A follow-up study of a national cohort of 36-year-olds was used to identify endogenous and exogenous vulnerability factors. Financial hardship and childhood risk were implicated for women, and financial hardship and unemployment for men. However, low rates of symptoms for 'stress-free' vulnerable individuals were only observed when chronic cases were excluded from analysis. Two alternative models are suggested: (i) a conditional vulnerability effect with an additional component to account for inception of long-term disorders; (ii) an additive burden model with vulnerability represented as a continuum from 'resilience' to 'susceptibility'. Their differentiation will require greater attention to the measurement of vulnerability and a fuller consideration of the significance of chronic disorders.