Arthritis and heart disease as risk factors for major depression: the role of functional limitation.
BACKGROUND
Major depression in later life is highest among people with chronic illness. Identifying amenable factors that mediate the relationship between known risk factors such as arthritis and heart disease with major depression is important to the design of clinical and public health strategies to reduce depression and its consequences.


OBJECTIVE
This study investigates factors amenable to clinical and public health intervention that could mediate the relationship between chronic illness and major depression.


METHODS
Population-based national sample.


METHODS
United States preretirement age (54-65) adults.


METHODS
A total of 7825 participants from the 1996 Health and Retirement Survey.


METHODS
The outcome is major depression based on standardized assessment. Independent variables include sociodemographics chronic illness profile, functional limitation, health and medical access.


RESULTS
A substantial burden of major depression is related to chronic illness, particularly arthritis (attributable risk [AR], 18.1%; 95% confidence interval [CI], 9.9-25.6) and heart disease (AR, 17.6%; 95% CI, 13.4-21.7). Functional limitation is the strongest investigated factor associated with depression (AR, 34.4%; 95% CI, 24.8-42.7) and attenuates the associations of arthritis and heart disease with depression.


CONCLUSIONS
Functional limitation mediates the association of arthritis and heart disease with major depression. This relationship offers potential clinical and public health strategies to reduce major depression in older adults through intervention and management of functional limitation. Alternatively, it might be possible to reduce functional loss through screening for depression, particularly among people with functional limitation, and effective mental health treatment. The importance for clinical management of depression, comorbidity, and functional limitation spectrum supports the value of systems-based medicine.
Dunlop
Dorothy D
DD
Institute for Health Services Research and Policy Studies, The Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA. ddunlop@northwestern.edu
Lyons
John S
JS
Manheim
Larry M
LM
Song
Jing
J
Chang
Rowland W
RW
D000203:Activities of Daily Living / Q000523:psychology*; D000368:Aged; D001168:Arthritis / Q000150:complications / Q000453:epidemiology / Q000523:psychology*; D015992:Body Mass Index; D002908:Chronic Disease / Q000453:epidemiology / Q000523:psychology; D015331:Cohort Studies; D015897:Comorbidity; D003866:Depressive Disorder / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D005260:Female; D015438:Health Behavior; D006297:Health Services Accessibility; D006331:Heart Diseases / Q000150:complications / Q000453:epidemiology / Q000523:psychology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014481:United States / Q000453:epidemiology