Circulating cerebral S100B protein is associated with depressive symptoms following myocardial infarction

Prevalence of depressive symptoms in the post-myocardial infarction (MI) period varies from 8 to 30%. Cerebral damage after MI, caused by transient ischemia, an inflammatory response or both, may contribute to development of post-MI depression. S100B is an established protein marker of cerebral damage. In a pilot study, the authors assessed whether S100B serum levels are: (1) increased during the week after MI, and (2) related to depressive symptoms during index hospital admission and the year following MI.

This pilot study is a substudy of the Myocardial Infarction and Depression Intervention Trial (MIND-IT). In 48 patients, serum levels of S100B were available at 1, 2, 3, 4 and 8 days following MI. Subsequently, in 27 patients, depressive symptoms were measured at 0, 3, 6, 9 and 12 months following MI with the Beck Depression Inventory (BDI). In 21 of the initial 48 patients, BDI data were lacking due to refusals to fill out BDI forms or missing data.

Significant and transient increases in serum S100B were observed in 81.3% of the 48 patients: 37.5% reached S100B serum levels comparable to serum levels found in acute brain injury (>0.20 microg/l) and 43.8% reached mildly elevated S100B serum levels comparable to serum levels found in depressive disorder (0.10-0.20 microg/l). In 18.7%, no S100B was detected in serum. Using non-parametric Spearman rank correlation tests, a trend towards an association was found between serum S100B and depressive symptoms during the post-MI year (rho values between 0.16 and 0.53) in 27 patients who completed both the S100B serum study and the BDI study.

Transiently elevated levels of S100B are suggestive of minor acute cerebral damage in the first days following MI and associated with depressive symptoms in the year following MI. Cerebral damage could be an important mechanism in the pathogenesis in a subtype of post-MI depression.