a1 Centre for Brain and Mental Health Research, Faculty of Health, University of Newcastle, New South Wales, Australia
a2 Immunology, Hunter Area Pathology Service, John Hunter Hospital, New South Wales, Australia
a3 Centre for Clinical Epidemiology and Biostatistics, Faculty of Health, University of Newcastle, New South Wales, Australia
a4 Hunter Medical Research Institute, John Hunter Hospital, New South Wales, Australia
Background Cross-sectional studies support an association between depression and inflammatory markers. However, little is known of their relationship in the context of antidepressant treatment. Our aim was to explore via meta-analysis whether antidepressant treatment is associated with a reduction in three inflammatory markers associated with depression.
Method A computerized search of EMBASE, Medline, PsycINFO and Cochrane Library databases was completed using subject headings for depression and either interleukin-6, C-reactive protein or interleukin-10, selecting studies which reported circulating levels of inflammatory markers before and after antidepressant treatment for people with depression. Outcome and moderator variables were coded for analysis, including inflammatory marker change, depression severity change, age, gender ratio, assay brand, treatment response and weight change.
Results Pooled effect sizes showed a significant decrease in interleukin-6 (n=14, d=−0.42, p=0.02), marginally significant decrease in C-reactive protein (n=8, d=−0.57, p=0.05) and a non-significant decrease in interleukin-10 (n=3, d=−0.45, p=0.14) after treatment. High levels of heterogeneity were observed, which may be associated with clinical variations between the studies such as weight gain, anxiety, incomplete remission and other individual differences and co-morbidities.
Conclusions The findings of this meta-analysis indicate that there may be a normalization of overactive inflammatory processes following antidepressant treatment.
(Received August 25 2011)
(Revised January 09 2012)
(Accepted January 17 2012)
(Online publication February 16 2012)
c1 Address for correspondence: Ms. S. A. Hiles, Centre for Brain and Mental Health Research, University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia. (Email: email@example.com)