Early onset of disease in patients with major depressive disorder may be linked to a specific inflammatory profile, based on data from 234 individuals.
Major depressive disorder (MDD) remains common, and evidence suggests that it is increasing among younger individuals, but data on early-onset MDD in adults are limited, Ana Paula Anzolin, a graduate student at the Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, and colleagues wrote.
Although previous studies have shown abnormal cytokine production in patients with MDD, the impact of inflammation on MDD and disease onset and progression remains unclear, they said.
In a study published in Psychiatry Research, the authors identified outpatients aged 18-85 years with confirmed MDD and scores of at least 8 on the HAM-D scale who were undergoing treatment at a single center. Early onset was defined as a diagnosis of MDD before age 30 years (99 patients) and late onset was defined as a diagnosis at age 30 years and older (135 patients). The researchers measured levels of interleukin-6, IL-1 beta, IL-10, and tumor necrosis factor alpha (TNF-alpha).
Overall, the level of cytokine profiles in early- versus late-onset disease was significantly higher for IL-1B and TNF-alpha (P < .001 for both). The significant difference between early- and late-onset disease remained regardless of comorbidity with autoimmune diseases, the researchers noted.
IL-6 levels were higher in the early-onset group and IL-10 levels were higher in the late-onset group, but these differences were not significant.
the researchers wrote.
The results also support findings from previous studies that suggest a divergence between early- and late adult–onset depression, they said. More research on early-onset MDD in adults is needed, as these patients tend to have more severe symptoms, more medical and psychiatric comorbidities, and an increased risk of depressive episodes and suicide attempts.
The study findings were limited by several factors including the lack of a control group, the retrospective assessment of disease onset, and the limited cytokines studied, which do not reflect changes in the entire immune network response, the researchers noted.
However, the study is the first known to examine the association of serum cytokines and early- and late-onset MDD in adults, and the results support the use of IL-1B and TNF-alpha as potential treatment targets in the development of new therapies for MDD, they concluded.
The study was supported by the Fundo de Incentivo à Pesquisa – Hospital de Clínicas de Porto Alegre, the Conselho Nacional de Desenvolvimento Científico e Tecnológico, and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. The researchers had no financial conflicts to disclose.