Depression, medical illness, and interleukin-1β in older cardiac patients

Objective: A model has been proposed in which atherosclerosis contributes to depression in later life by the effects of cytokines on central monoamine systems. We collected pilot data to test the hypothesis that interleukin-1β (IL-1β) is associated with depression in a cardiac patient group. Method: Thirty-seven subjects completed research evaluations that included depression diagnosis (Structured Clinical Interview for DSM-III-R), depressive symptom severity (Hamilton Rating Scale for Depression), medical illness burden (Cumulative Illness Rating Scale), and serum IL-1β level measured by enzyme linked immunosorbent assay. Results: Serum IL-1β level was not significantly associated with depressive symptom severity or depression diagnosis, whether or not controlled for medical illness burden, age, and gender. IL-1β level was significantly correlated with medical illness burden. Conclusions: We did not confirm our study hypothesis. The correlation of IL-1β level with medical illness burden likely reflects its release as part of the "sickness response" in a wide variety of disease states. Further research using a larger sample size and a non-cardiac comparison group is warranted.