Age differences in the prevalence and co-morbidity of DSM-IV major depressive episodes: results from the WHO World Mental Health Survey Initiative.
BACKGROUND
Although depression appears to decrease in late life, this could be due to misattribution of depressive symptoms to physical disorders that increase in late life.


METHODS
We investigated this issue by studying age differences in co-morbidity of DSM-IV major depressive episodes (MDE) with chronic physical conditions in the WHO World Mental Health (WMH) surveys, a series of community epidemiological surveys of respondents in 10 developed countries (n=52,485) and 8 developing countries (n=37,265). MDE and other mental disorders were assessed with the Composite International Diagnostic Interview (CIDI). Organic exclusion rules were not used to avoid inappropriate exclusion of cases with physical co-morbidity. Physical conditions were assessed with a standard chronic conditions checklist.


RESULTS
Twelve-month DSM-IV/CIDI MDE was significantly less prevalent among respondents ages 65+ than younger respondents in developed but not developing countries. Prevalence of co-morbid mental disorders generally either decreased or remained stable with age, while co-morbidity of MDE with mental disorders generally increased with age. Prevalence of physical conditions, in comparison, generally increased with age, while co-morbidity of MDE with physical conditions generally decreased with age. Depression treatment was lowest among the elderly in developed and developing countries.


CONCLUSIONS
The weakening associations between MDE and physical conditions with increasing age argue against the suggestion that the low estimated prevalence of MDE among the elderly is due to increased confounding with physical disorders. Future study is needed to investigate processes that might lead to a decreasing impact of physical illness on depression among the elderly.
Kessler
Ronald C
RC
Department of Health Care Policy, Harvard Medical School, Boston, Massachusetts, USA.
Birnbaum
Howard G
HG
Shahly
Victoria
V
Bromet
Evelyn
E
Hwang
Irving
I
McLaughlin
Katie A
KA
Sampson
Nancy
N
Andrade
Laura Helena
LH
de Girolamo
Giovanni
G
Demyttenaere
Koen
K
Haro
Josep Maria
JM
Karam
Aimee N
AN
Kostyuchenko
Stanislav
S
Kovess
Viviane
V
Lara
Carmen
C
Levinson
Daphna
D
Matschinger
Herbert
H
Nakane
Yoshibumi
Y
Browne
Mark Oakley
MO
Ormel
Johan
J
Posada-Villa
Jose
J
Sagar
Rajesh
R
Stein
Dan J
DJ
D000328:Adult; D000367:Age Factors; D000368:Aged; D015897:Comorbidity; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D003906:Developing Countries; D003937:Diagnosis, Differential; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D008875:Middle Aged; D013001:Somatoform Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D014944:World Health Organization; D055815:Young Adult