Low-grade inflammation differentiates between symptoms of apathy and depression in community-dwelling older individuals.
BACKGROUND
Systemic low-grade inflammation has repeatedly been associated with depression in old age, but the relationship with apathy is less clear. The present study assessed whether C-reactive protein (CRP) is differentially associated with symptoms of apathy and depression.


METHODS
A population-based cohort study was carried-out. At baseline and after two and four years of follow-up, CRP levels were assessed and symptoms of apathy and depression were measured using the 15-item Geriatric Depression Scale. Logistic regression analysis was used to investigate the cross-sectional and longitudinal associations of CRP with symptoms of apathy and depression.


RESULTS
Two thousand forty-seven community-dwelling participants (70-78 years) without a history of cardiovascular disease or stroke were studied. A cross-sectional association was found between CRP and apathy symptoms at three time points (odds ratio (OR) per natural log unit increase in CRP: baseline visit = 1.40, 95% CI = 1.12-1.75; two-year follow-up visit = 1.62, 95% CI = 1.17-2.25; four-year follow-up visit = 1.51, 95% CI = 1.03-2.21). This did not change after adjustment for demographics and depressive symptoms, and was slightly attenuated after adjustment for cardiovascular risk factors. No cross-sectional association was found with depressive symptoms. Baseline CRP did not predict incident apathy or depressive symptoms during four years of follow-up.


CONCLUSIONS
Increased CRP levels are associated with apathy symptoms but not with depressive symptoms. This suggests a differential effect of inflammation on apathy and depression. In older persons, symptoms of apathy may be a behavioral manifestation of concurrent low-grade inflammation.
Department of Neurology,Academic Medical Center,University of Amsterdam,Meibergdreef 9,1105 AZ,Amsterdam,the Netherlands.
Lisa S M
LS
Eurelings
Department of Neurology,Radboud University Medical Center,Geert Grooteplein-Zuid 10,6525 GA,Nijmegen,the Netherlands.
Edo
E
Richard
Department of Neurology,Academic Medical Center,University of Amsterdam,Meibergdreef 9,1105 AZ,Amsterdam,the Netherlands.
Piet
P
Eikelenboom
Department of Neurology,Academic Medical Center,University of Amsterdam,Meibergdreef 9,1105 AZ,Amsterdam,the Netherlands.
Willem A
WA
van Gool
Department of General Practice,Academic Medical Center,University of Amsterdam,Meibergdreef 15,1105 AZ,Amsterdam,the Netherlands.
Eric P
EP
Moll van Charante
D000368:Aged / Q000523:psychology; D057565:Apathy / Q000502:physiology; D002097:C-Reactive Protein / Q000032:analysis; D003430:Cross-Sectional Studies; D003863:Depression / Q000503:physiopathology*; D005260:Female; D006801:Humans; D057187:Independent Living / Q000523:psychology* / Q000706:statistics & numerical data; D007249:Inflammation / Q000523:psychology*; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D011569:Psychiatric Status Rating Scales
D002097:C-Reactive Protein
cardiovascular disease