The interrelationship of neuroticism, sex, and stressful life events in the prediction of episodes of major depression.
OBJECTIVE
Three potent risk factors for major depression are female sex, the personality trait of neuroticism, and adversity resulting from exposure to stressful life events. Little is known about how they interrelate in the etiology of depressive illness.


METHODS
In over 7,500 individual twins from a population-based sample, the authors used a Cox proportional hazard model to predict onsets of episodes of DSM-III-R major depression in the year before the latest interviews on the basis of previously assessed neuroticism, sex, and adversity during the past year; adversity was operationalized as the long-term contextual threat scored from 15 life event categories.


RESULTS
In the best-fit Cox model for prediction of depressive onsets, neuroticism, female sex, and greater adversity all strongly increased risk for major depression. An interaction was seen between neuroticism and adversity such that individuals with high neuroticism were at greater overall risk for major depression and were more sensitive to the depressogenic effects of adversity. An interaction was also seen between adversity and sex, as the excess risk for major depression in women was confined to individuals with low stress exposure.


CONCLUSIONS
Psychosocial adversity interacts both with neuroticism and with sex in the etiology of major depression. The impact of neuroticism on illness risk is greater at high than at low levels of adversity, while the effect of sex on probability of onset is the opposite--greater at low than at high levels of stress. Complete etiologic models for major depression should incorporate interactions between risk factor classes.
Kendler
Kenneth S
KS
Virginia Institute for Psychiatry and Behavioral Genetics and Department of Psychiatry, Medical College of Virginia, Virginia Commonwealth University, Richmond, 23298-0126, USA. kendler@hsc.vcu.edu
Kuhn
Jonathan
J
Prescott
Carol A
CA
D000328:Adult; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000453:epidemiology* / Q000523:psychology*; D005260:Female; D006801:Humans; D008016:Life Change Events; D008297:Male; D009497:Neurotic Disorders / Q000453:epidemiology* / Q000523:psychology*; D011159:Population Surveillance; D011446:Prospective Studies; D014427:Twins / Q000235:genetics