Light Therapy Alleviates Addiction-Related Symptoms and Reshapes Habenula and Midbrain Pathways

The treatment of internet gaming disorder (IGD) poses a significant challenge. Light therapy has demonstrated efficacy in preventing cocaine-driven reinstatement in a rodent model. The potential of light therapy, along with its underlying neural mechanisms, in treating IGD remains largely uninvestigated. A total of 104 participants are included in the RCT and 69 in the fMRI analysis. The intervention involves 14 daily sessions of light therapy, light placebo, or cognitive training. At post-intervention, light therapy group shows treatment effects comparable to those of cognitive training group, with greater reductions in addiction severity, weekly gaming duration, craving, and withdrawal symptoms than the placebo group. Longitudinal fMRI shows reduced activation in right inferior orbitofrontal cortex (iOFC), left inferior frontal gyrus, and right insula. Using habenula, ventral tegmental area (VTA), and dorsal raphe nuclei (DRN) as seeds, light therapy increases functional connectivity between habenula and medial OFC (mOFC), and VTA and mOFC. These increases are significantly correlated with reductions in withdrawal/craving symptoms. Importantly, changes in withdrawal symptoms mediate the association between habenula-mOFC functional connectivity and addiction severity. Our findings suggest light therapy is effective in alleviating withdrawal symptoms and ultimately reducing addiction severity by reshaping the habenula-mOFC functional connectivity in IGD.