Abnormal C-reactive protein blood levels as a specific biomarker of major depression and non-remission under antidepressants in schizophrenia.

BACKGROUND

C-reactive protein (CRP) is a general marker of peripheral inflammation and has been shown to be a good marker of neuroinflammation. CRP has been found to be elevated in patients with mood disorders (especially unipolar disorders (UD) and in schizophrenia (SZ)) but also to be lowered by antidepressants.

OBJECTIVE

The objectives were (i) to determine the prevalence of major depression, antidepressant prescription and remission under antidepressant in a stabilized population of SZ and UD patients consulting in a daily hospital, and (ii) to determine if CRP was a marker of major depression and remission under antidepressant in these SZ and UD populations.

METHODS

Abnormal CRP was defined by a CRP blood level ≥ 3 mg/L. Depressive symptoms were assessed by the Calgary Depression Rating Scale score. The clinicians were blinded of the CRP status of the patient.

RESULTS

411 patients were included (272 SZ and 139 UD). 171 (41.6%) were diagnosed with current major depression (74 (27.2%) for SZ and 97 (69.8%) for UD). 86 SZ (31.6%) and 119 UD (85.6%) were treated by antidepressant. Only 28/74 (37.8%) of the SZ subjects with major depression were administered antidepressants vs. 87/97 (89.7%) for UD. The non-remission rate under antidepressant was 28/86(32.6%) for SZ and 87/119 (73.1%) for UD. Overall, 105 (40.1%) of SZ and 39 (28.1%) of UD patients were found to have abnormal CRP blood levels. Abnormal CRP levels were significantly associated with increased MDD and more strongly with increased rates of non-remission under antidepressants in SZ patients, independently of age, gender, psychotic symptomatology, functioning, tobacco smoking and metabolic syndrome. This result was not replicated in UD patients, which suggests that CRP may be a specific marker of major depression and remission under antidepressant in SZ patients.

CONCLUSION

The development of biomarkers in psychiatry may orientate specific etiologic therapies in patients with mental disorders. The present findings suggest that major depression is frequent in SZ patients and that increased CRP levels are associated with non-remission under antidepressants in this population. Anti-inflammatory strategies may be particularly useful in this specific population.