Life events and early onset depression: cause or consequence?
BACKGROUND
Adverse life events prior to episodes of depression are assumed to play a causal role. Earlier studies have, however, not adequately controlled for the potential confounding effects of previous depression.


METHODS
A two-phase study was nested within a six-wave population based cohort study of 1947 adolescents. Interviews at two assessment phases with the CIS-R and CIDI were used to generate ICD-10 diagnoses of depressive disorder. Life events with longer-term contextual threat were reported for the 6 months before first diagnosis and categorized on the basis of participant appraisal as negative and neutral/positive in effects. Previous depressive and anxiety symptoms were measured 6 months earlier.


RESULTS
Pre-existing depressive and anxiety symptoms predicted later events, increasing three-fold the risks for both neutral/positive and negative events in females and increased seven-fold the risk of negative events in males. Life events in turn predicted the onset of depressive disorder independently of previous symptoms. Single negative events held an over five-fold elevated risk and multiple events an almost eight-fold higher risk. Personal threat and loss were associated with disorder in females but not males.


CONCLUSIONS
The findings are consistent with a causal role for life events in early episodes of depression. The association also reflects a reciprocal relationship in which earlier symptoms predict later events, perhaps as a result of an individual's attempts to change unfavourable social circumstances.
Murdoch Children's Research Institute, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.
G C
GC
Patton
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Coffey
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M
Posterino
J B
JB
Carlin
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Bowes
D000223:Adaptation, Psychological; D000293:Adolescent; D001008:Anxiety Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D015984:Causality; D015331:Cohort Studies; D015897:Comorbidity; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D005260:Female; D006801:Humans; D007206:Individuality; D008016:Life Change Events; D008297:Male; D010552:Personality Assessment; D011594:Psychometrics; D012307:Risk Factors; D014739:Victoria