Correlation between interleukin-6 levels and methadone maintenance therapy outcomes.

BACKGROUND: The outcome of methadone maintenance therapy (MMT) varies in each patient with opioid use disorder (OUD). Opioid abuse activates proinflammatory processes by increasing cytokine production and impairing neurotrophic factor expression, and possibly leads to a vicious cycle that hinders recovery. Therefore, we investigated whether markers of inflammation and neurotrophic expression correlate with the MMT outcomes in OUD patients. METHOD: We investigated OUD patients undergoing MMT and followed them up for 12 weeks. We measured plasma tumor necrosis factor (TNF)-α, C-reactive protein (CRP), interleukin (IL)-6, IL-1ß, transforming growth factor (TGF)-ß1, brain-derived neurotrophic factor (BDNF), urinary morphine tests, and plasma morphine levels at baseline and on weeks 1, 4, 8, and 12 during MMT. Multiple linear regressions and generalized estimating equations (GEEs) were used to examine the correlation between the cytokine and BDNF levels and MMT outcomes. RESULTS: We initially enrolled 104 patients, but only 78 patients completed end-of-study assessments. Plasma levels of CRP, TGF-ß1, and BDNF fell during MMT. Plasma IL-6 levels were significantly associated with plasma morphine levels (P = 0.005) and urinary morphine-positive (+) results (P = 0.04), and significantly associated with poor compliance (P = 0.009) and early dropout from MMT (P = 0.001). However, other cytokine and BDNF levels were not consistently associated with MMT outcomes. CONCLUSION: Higher IL-6 levels were associated with poor MMT outcomes. Additional studies on regulating IL-6 expression to improve treatment outcomes in OUD patients might be warranted.

No changes in striatal dopamine transporter in antidepressant-treated patients with major depression.

Selective serotonin reuptake inhibitors and serotonin norepinephrine reuptake inhibitors are the mainstay treatment for major depressive disorder, but whether their therapeutic mechanisms involve the dopaminergic system remains inconclusive. Eight participants with major depressive disorder were administered single-photon emission computed tomography with [(99m)Tc] TRODAT-1 both before and after 24 weeks of antidepressant treatment to evaluate the change in striatal dopamine transporter (DAT) availability. All participants were responders (≥50% reduction in Hamilton Depression Rating Scale score). The DAT availability did not change (P=0.58), as the Hamilton Depression Rating Scale score decreased (P=0.02). Striatal DAT availability remains intact during long-term antidepressant treatment in patients with major depressive disorder.