Structure of internalising symptoms in early adulthood.
BACKGROUND
Debate surrounds the underlying structure of internalising disorders including major depression, generalised anxiety disorder, phobias and panic disorders.


OBJECTIVE
To model the within-time and across-time relationships of internalising symptoms, incorporating effects from generalised internalising and disorder-specific components of continuity.


METHODS
Data were gathered from a 25-year longitudinal study of a birth cohort of 953 New Zealand children. Outcome measures included DSM-IV symptom scores for major depression, generalised anxiety disorder, phobia and panic disorder at the ages of 18, 21 and 25 years.


RESULTS
Structural equation modelling showed that, within-times, a common underlying measure of generalised internalising explained symptom score comorbidities. Across-time correlation of symptom scores was primarily accounted for by continuity over time in generalised internalising. However, for major depression and phobia there was also evidence of across-time continuity in the disorder-specific components of symptoms.


CONCLUSIONS
Internalising symptoms can be partitioned into components reflecting both a generalised tendency to internalising and disorder-specific components.
Fergusson
David M
DM
Christchurch Health and Development Study, Christchurch School of Medicine and Health Sciences, PO Box 4345, Christchurch, New Zealand. david.fergusson@chmeds.ac.nz
Horwood
L John
LJ
Boden
Joseph M
JM
D000293:Adolescent; D000328:Adult; D001008:Anxiety Disorders / Q000175:diagnosis / Q000523:psychology*; D002648:Child; D002675:Child, Preschool; D003866:Depressive Disorder / Q000175:diagnosis / Q000523:psychology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007389:Internal-External Control; D008137:Longitudinal Studies; D008297:Male; D008960:Models, Psychological; D009520:New Zealand