Characteristics of inflammation-related depression

Background: Whether depressed patients with evidence of inflammation are more appropriate candidates for immunotherapies is being tested in clinical trials. However, studies of the clinical and phenotypic profile of depressed patients with evidence of inflammation are scarce. Methods: We investigated clinical characteristics of 84 depressed patients, grouped as those with and without evidence of inflammation. Results: After adjusting for potential confounders, regression analyses showed that inflammation (C-reactive protein greater than or equal to 3mg/L) was associated with higher depression severity (p<0.01), somatic symptoms (p<0.01), state anxiety (p less than 0.01), perceived stress (p<0.01), fatigue (p<0.01), and poorer quality of life (p<0.01). Logistic regression revealed that, at symptom level, the inflamed group had nearly four-to-seven fold increase in guilty feelings (p<0.01), pessimism (p=0.01), concentration difficulties (p=0.02), and indecisiveness (p=0.04). Conclusion: We highlight clinical features associated with inflammation-related depression. These results could aid patient selection in future clinical trials testing immunotherapies in depression. Replication of these findings in larger samples is required.