Transcranial Photobiomodulation in Anxiety Disorders

BEHAVIORAL

Attention bias assessment and modification

Attention bias assessment and modification involve two versions of the dot-probe task. These tasks are based on the premise that repeated attention shifts can retrain attentional biases, with the expectation that reducing attentional bias toward threats will alleviate sub-clinical anxiety symptoms.

DEVICE

Transcranial photobiomodulation

Participants will receive near-infrared light at 1064 nanometers to the right side of the forehead for 8 minutes. The investigators have introduced this form of transcranial photobiomodulation (tPBM) as a means of human cognitive enhancement, and as an adjunct for attention bias modification for the reduction of symptoms of depression. In the present study, the investigators wish to extend these findings to the use of attention bias modification for the reduction of sub-clinical anxiety.

Composite cognitive score in the dot-probe task

Time frame: Visit 1 (baseline), Visit 2 (three days after Visit 1), Visit 3 (1 week after Visit 2)

The participant pays attention to a fixation cross in the center of the screen, which is followed by the presentation of two images on the left and right of the screen. One of these new images is a "threat" image, while the other is neutral. Following each trial of stimuli presentation, a probe type ("\<" vs. "\>") will randomly appear in the same location previously occupied by either the threatening or neutral image and remain on the screen until the participant has responded. Participants respond to the probe type by pressing the "←" or the "→" arrow key, respectively, on the keyboard, as quickly but as accurately as possible. The probe randomly replaces the neutral or the negative stimulus with equal frequency (50/50). The single primary outcome is the composite cognitive score which is calculated on the basis of performance in this task.

Change in concentration of oxygenated hemoglobin as measured by functional near-infrared spectroscopy

Time frame: Visit 1 (baseline), Visit 2 (three days after Visit 1), Visit 3 (1 week after Visit 2)

Hemodynamic activity is assessed non-invasively using near-infrared spectroscopy. In this procedure, a participant wears an apparatus on the head which contains an array of light sources and detectors. Light is applied to the surface of the skin, and a small fraction of the light passes through the underlying tissue and reflects back to the surface, where it is detected and the number of photons at specific light wavelengths are counted by a computer. This photon count can be converted to changes in concentration of metabolic indices, such as oxygenated/deoxygenated hemoglobin.

What is a clinical trial?

A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.

Is it safe to participate?

Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.

Will I be compensated?

Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.

Will I receive a placebo instead of treatment?

When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.

Can I leave a trial if I change my mind?

Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.

How long does a clinical trial last?

Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.