Increased Interleukin-6 Levels in Responders with Treatment-Resistant Depression After Bright Light Therapy

Area of Science:

• Neuroscience
• Psychiatry
• Immunology

Background:

• Treatment-resistant depression (TRD) presents a significant clinical challenge.
• Peripheral interleukin-6 (IL-6) is implicated in TRD presence and treatment response.
• The impact of bright light therapy (BLT) on IL-6 in TRD is unknown.

Purpose of the Study:

• To investigate the effect of BLT on serum IL-6 levels in patients with TRD.
• To correlate changes in IL-6 with depression severity and treatment response to BLT.

Main Methods:

• Serum IL-6 levels were measured at baseline and after 4 weeks of BLT in 54 female TRD patients.
• Depression severity was assessed using the Hamilton Rating Scale for Depression (HAMD)-17 and Montgomery-Åsberg Depression Rating Scale (MADRS).
• A cohort of 50 healthy females served as controls.

Main Results:

• TRD patients exhibited higher baseline IL-6 levels compared to healthy controls.
• BLT significantly reduced HAMD-17 and MADRS scores, indicating improved depressive symptoms.
• Serum IL-6 levels were not significantly altered by BLT overall, but increased in patients who responded to treatment.

Conclusions:

• BLT is an effective intervention for reducing depressive symptoms in TRD.
• Neuroinflammation, potentially involving IL-6, may play a role in TRD pathogenesis and treatment.
• Elevated IL-6 levels in BLT responders may serve as a biomarker for treatment response.