The investigators have previously shown that non-invasive methods of brain stimulation such as the administration of transcranial infrared light to the prefrontal cortex (PFC) can result in improvements to cognition and emotion as well as brain oxygenation. This method is called transcranial photobiomodulation (tPBM). The investigators hypothesize that tPBM can improve cognition and brain oxygenation in adults with attention deficit hyperactivity disorder (ADHD). The investigators will investigate the effects of repeated tPBM sessions on cognitive functioning in adults with ADHD. Specifically, the investigators hypothesize that participants that receive tPBM will show improvements in response control, sustained attention, and working memory, as well as improvements in prefrontal hemodynamics and a reduction in ADHD symptoms.
This will be a double-blind, sham-controlled study to evaluate the neurobehavioral and PFC neurometabolic effects of repeated tPBM sessions in adults with ADHD. Adults with a history of medically-diagnosed ADHD will be recruited. Participants will be randomized to two arms: (1) active tPBM or (2) sham tPBM. All participants will complete three in-person sessions and one remote follow-up visit conducted online. Participant will receive three weekly sessions of tPBM targeting the PFC using a 1064 nm laser. Cognitive performance will be assessed using the continuous performance task and 2-back task at baseline and after the final tPBM session. The investigators predict that participants receiving active tPBM will show improvements in sustained attention, impulse control, and working memory. Functional near-infrared spectroscopy recordings, collected at baseline and post-treatment, will be used to evaluate changes in PFC hemodynamic response and network interactions (functional connectivity). The investigators predict that active tPBM will enhance the PFC hemodynamic response and strengthen network interactions across prefrontal subregions. Lastly, ADHD symptomatology will be assessed using the Adult ADHD Self-Report Scale at baseline, post-treatment, and at a four-week follow-up after tPBM. The investigators predict that participants receiving active tPBM will report progressive reductions in ADHD symptoms across time points.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
140
Active transcranial photobiomodulation to the forehead targeting prefrontal cortex involves administration of 1064-nm light delivered via laser with a 4 centimeter beam diameter and 250 mW/cm2 power density for 8 minutes per treatment.
Identical procedure as active group, but without 1064-nm light emitted by the device.
The University of Texas at Austin
Austin, Texas, United States
Performance on the Continuous Performance Task
The Continuous Performance Task is a widely-used cognitive measure to evaluate sustained attention, vigilance, and response control. Participants respond to letters presented on a computer screen and inhibit their responses to the letter X. There is no score on a scale. An increase in Correct Rejections on CPT = better inhibition = better outcome of treatment.
Time frame: 1. Pre-Treatment: Baseline (Visit 1). 2. Post-treatment: Two weeks later (Visit 3).
Prefrontal oxygenation (functional near-infrared spectroscopy)
Participants will wear a head-mounted functional near-infrared spectroscopy device that records changes in the concentrations of oxygenated hemoglobin potentially resulting from the treatment.
Time frame: 1. Pre-Treatment: Baseline (Visit 1). 2. Post-treatment: Two weeks later (Visit 3).
Scores on the Adult ADHD Self-Report Scale (ASRS) questionnaire
The ASRS is an 18-question self-assessment tool created by the World Health Organization (WHO) which evaluates symptom severity of ADHD. Minimum score=18; maximum score=90; high score = more ADHD symptoms; lower score after treatment = better outcome.
Time frame: 1. Pre-Treatment: Baseline (Visit 1). 2. Post-treatment: Two weeks later (Visit 3). 3. Follow-up: Four weeks later (Online).
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