Background. Neuroticism and somatic complaints are linked, and the aim of this study is to disentangle which mechanisms may be responsible for this association.

Method. In a stratified sample of 7076 adults (18–65 years), neuroticism, 22 self-reported chronic somatic conditions and five broad CIDI-diagnosed psychiatric syndromes were assessed at baseline and, in 3625 (51%) subjects, 3 years later. Using path analysis we examined whether neuroticism has direct links with future somatic morbidity and, conversely, whether morbidity at baseline is linked with higher neuroticism later on.

Results. Neuroticism at baseline is associated with psychiatric and somatic morbidity at follow-up after 3 years (31% and 24%, respectively, are direct associations, i.e. unmediated by each other or neuroticism at follow-up and independent of morbidity at baseline). Conversely, somatic and psychiatric morbidity at baseline are associated with increased neuroticism at follow-up (27% and 15%, respectively, are direct associations).

Conclusions. Neuroticism raises risk for psychiatric and somatic morbidity but also results from them. It represents a central nexus in the process of morbidity accumulation.