Purpose: Investigating the effects of non-invasive transcranial alternating current stimulation (tACS) on healthy participants and participants with mood disorders. Participants: 40 males and females, ages 18-65, with depressed mood; 40 healthy males and females, ages 18-65, free of neurological or psychiatric conditions. Procedures: This is a single visit study with two stimulation conditions (tACS and sham tACS). The session will begin with clinical assessments (including confirmation of diagnosis), followed by an interactive EEG task, then a 7 minute resting state EEG (2 minutes eyes closed, 5 minutes eyes open), followed by the stimulation session (40 minutes of tACS or sham tACS), followed by an additional 5 minute resting state EEG. The stimulation will involved 40 minutes of transcranial alternating current stimulation, 2 mA in amplitude and at individualized alpha frequency (determined by the 2 minutes eyes closed EEG recording; between 8 and 12Hz).
Participants will report for a study visit and will review and sign a consent form. Participants will complete several clinical assessments and also take a urine drug test and urine pregnancy test (if applicable). Eligibility will be re-assessed by the investigators before the participant moves on to the next phase. If the participant still qualifies, the participant will first be fitted with two 5x5cm electrodes placed over F3/F4 (10-20 measurement system) and one 5x7cm electrode placed over Cz. In addition, the participant will have a 128-channel EEG net placed on their head. Participants will provide a saliva sample to assess for brain-derived neurotrophic factor (BDNF), which may affect how the participant's brain responds to stimulation. Once the participant is fitted with this equipment, the participant will complete two interactive EEG tasks, then 2-minute resting state EEG with the participant's eyes closed, then a 5-minute resting state EEG with the participant's eyes open. Following these recordings, participants will respond to additional questionnaires. Immediately following this, the participant will receive 40 minutes of stimulation (tACS or sham tACS). During this stimulation, participants will sit comfortably upright and awake. After stimulation has completed, participants will respond to additional questionnaires. Once completed, participants will then complete an additional 5-minute resting state EEG with the participant's eyes open, as well as complete one of the additional interactive EEG tasks. Finally, participants will respond to a blinding questionnaire to assess if the participant thought that the participant received stimulation. Once complete, the participant will leave. This session is estimated to last about 4 hours.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
84
The participant will receive up to one minute of tACS stimulation until the stimulation fades. Sham stimulation mimics the skin sensations a participant would experience during a tACS session.
Transcranial alternating current stimulation (tACS) is a method of noninvasive brain stimulation in which weak electrical current are applied to the scalp in a sine wave pattern to induce cortical oscillations at the frequency at which they are applied.
University of North Carolina Chapel Hill
Chapel Hill, North Carolina, United States
Change in Alpha Frequency Electrical Activity in Left Frontal Cortex From Stimulation
Fast Fourier transform is applied to 5 minutes of EEG data before and after intervention. Primary outcome is the difference in alpha frequency amplitude (8-12 Hz) in the left frontal cortex from baseline as a result of intervention.
Time frame: 5 minute recording before and after intervention
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