The serum interleukin-18 is a potential marker for development of post-stroke depression

Depression is a common mood disorder affecting stroke patients. It is associated with poorer outcome and increased mortality in stroke patients. The aim of this work was to test whether serum levels of proinflammatory cytokines are correlated with the development of depression after stroke.

One hundred ischemic stroke patients admitted to the hospital within the first 24 hours after stroke onset were consecutively recruited and followed up for 6 months. The 17-item Hamilton Depression Rating Scale (HDRS) and Montgomery-Asberg Depression Rating Scale (MADRS) were used to screen for depressive symptoms on days 3, 7 and 14 after admission and at 6 months after stroke onset. Based on the symptoms elicited from these two scales, diagnoses of depression were made in accordance with DSM-IV criteria for post-stroke depression. Serum levels of proinflammatory cytokines (IL-6, IL-18 and TNF-alpha) of all the patients were determined by ELISA on both days 1 and 7 after admission. Meanwhile, 50 healthy control subjects were also recruited; they underwent measurement of serum levels of proinflammatory cytokines once.

Thirty-seven patients (37.0%) were diagnosed as having major depression at 2 weeks. Serum IL-18 on both days 1 and 7 was significantly higher in both post-stroke depression patients and non-post-stroke depression patients than in normal controls. Serum IL-18 on day 7 was significantly higher in post-stroke depression patients than in non-post-stroke depression patients. Serum IL-18 >377.84 pg/ml on day 7 was independently associated with incident post-stroke depression at the acute stage of stroke (odds ratio: 12.280, 95% confidence interval: 3.848-39.190, p<0.001 after adjustment). At 6 months, 31 patients (33.0%) were diagnosed with major depression. Serum IL-18 >376.67 pg/ml on day 7 was independently associated with post-stroke depression at 6 months (odds ratio: 7.431, 95% confidence interval: 1.741-31.712, p=0.007 after adjustment).

Serum IL-18 on day 7 after admission may predict the risk of post-stroke depression both at the acute stage of stroke and at 6 months post-stroke.