Transcranial Pulse Near-Infrared Light in Generalized Anxiety Disorder: a Placebo-Controlled Study

The purpose of this study is to see if using Transcranial Light Therapy (TLT), also called near- infrared light, helps improve symptoms of generalized anxiety disorder (GAD). Subjects will be randomized at a 1:2 ratio into 2 groups: pulse light (TLT) and sham. The sham group will be randomized after 8 weeks at a 1:1 ratio in to TLT and sham. The study involves 1 screening visit which may last up to 3 hours, 16 weekly study visits, and one follow-up visit. There are 2 in-office treatment visits, during which a clinician applies transcranial light therapy to the participant's head for about 30 minutes. The other study visits involve assessments with a study clinician. The participants will administer the treatment once daily at home during the 16-week treatment period. If a participant qualifies for the study, the study team assigns the participant by chance to receive either active transcranial light therapy or sham transcranial light therapy treatment. During sham transcranial light therapy visits, the transcranial light therapy device will not produce near infrared waves (e.g., light energy that cannot penetrate the skin and cranium). Participants have more than an equal chance of being assigned to the active transcranial light therapy or the sham transcranial light therapy over the course of the study. Neither the participant, nor the clinician, nor any research staff other than the study statistician will know which study group the participant belongs. Participants are randomized a second time after 8-weeks in the study. If the participant were in the sham group the first 8-weeks, that participant may receive the active transcranial light therapy treatment after re-randomization. If the participant were already in the active transcranial light therapy group during the first 8-weeks the participant continues receiving the active treatment. All in all, participants have a 2 in 3 chance of receiving the active transcranial light therapy treatment at some point during the study.