Interleukin-1 receptor antagonist and incident depressive symptoms over 6 years in older persons: the InCHIANTI study.
BACKGROUND
We test the hypothesis that in older persons higher plasma levels of inflammatory markers predict the development of depressive symptoms during a 6-year follow-up.


METHODS
This study is part of the InCHIANTI (Invecchiare in Chianti, aging in the Chianti area) study, a prospective population-based study of older persons. The sample consisted of 991 participants, ages 65 years and older. Serum levels of C-reactive protein, interleukin (IL)-1beta, IL-1 receptor antagonist (ra), tumor necrosis factor-alpha, IL-6, IL-6 receptor, and IL-18 were measured. Depressive symptoms were assessed at baseline and at the 3- and 6-year follow-ups with the Center for Epidemiological Studies-Depression Scale (CES-D). Depressed mood was defined as CES-D > 20. Potential confounders were baseline variables related to sociodemographic, somatic health, and functional status.


RESULTS
At baseline, IL-1ra levels were significantly higher (p = .004) in depressed compared with nondepressed participants. After adjustment for confounders, among subjects free of depression at baseline, those in the third and fourth IL-1ra quartiles compared with those in the lowest quartile had, respectively, a 2.32-fold (95% confidence interval: 1.21-4.42, p = .01) and 2.78-fold (95% confidence interval: 1.47-5.26, p = .002) higher risk of developing depressed mood during a 6-year follow-up.


CONCLUSIONS
In old age, persons with high plasma levels of IL1-ra had a higher risk of developing depressive symptoms over time. These findings suggest a potential causal role for inflammation in the development of depressive symptoms in older persons.
Milaneschi
Yuri
Y
Tuscany Health Regional Agency, ASF, Florence, Italy.
Corsi
Anna Maria
AM
Penninx
Brenda W
BW
Bandinelli
Stefania
S
Guralnik
Jack M
JM
Ferrucci
Luigi
L
D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000378:metabolism; D016009:Chi-Square Distribution; D018672:Community Health Planning; D003863:Depression / Q000097:blood* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D053590:Interleukin 1 Receptor Antagonist Protein / Q000097:blood*; D053583:Interleukin-1beta / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D016209:Interleukin-8 / Q000097:blood; D007558:Italy; D008137:Longitudinal Studies; D008297:Male; D011569:Psychiatric Status Rating Scales; D019947:Receptors, Interleukin-6 / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D053590:Interleukin 1 Receptor Antagonist Protein; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D019947:Receptors, Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein