Multitasking Behavior
Conditions
Brief summary
The goal is to replicate in-lab results from transcranial alternating current stimulation (tACS) with at-home tACS.
Detailed description
Participants will be assessed in-lab on multitasking and sustained attention abilities. Participants will be sent home with a tACS device to be used at-home for five days while engaged in a multitasking paradigm that is different from the multitasking outcome measure used pre/post tACS. After the at-home stimulation is complete, participants return to UCSF for a final in-lab assessment of multitasking and sustained attention ability.
Interventions
DEVICETranscranial alternating current stimulation
Transcranial alternating current stimulation across the prefrontal cortex using electrodes F3 and F4.
Sponsors
University of California, San Francisco
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* English speaking * Grade 12 or more education * Normal or corrected to normal vision and hearing * Ability to complete cognitive tasks * Ability to cooperate and comply with all study procedures * Ability to tolerate tACS
Exclusion criteria
* Neurological or psychiatric disorders * Family history of epilepsy * History of seizures * Prior head trauma * Pregnant * Implanted electronic devices (e.g., pacemaker) * IQ \< 80 * Taking psychotropic medication * Taking anti-depressants or anti-anxiety medication * Substance abuse * Color blind * Glaucoma * Macular degeneration * Amblyopia * Strabismus
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Multitasking Performance Cost (Neuroracer Performance Change From Baseline) | Pre-tACS and post-tACS (1 week later) | Assessment of multitasking ability using change from baseline scores in d' cost (metric of discriminability). Discrimination performance (d') was measured for each participant by comparing hit (correct responses to target signs) rates and false alarm (responses to non-targets) rates and calculated as d' = Z (hits) - Z (false alarms). d' cost was then calculated as the ratio of d' during single task target discrimination task to multitask target discrimination, expressed as percentage cost. |
| Single Task Performance Change | Pre-tACS and post-tACS (1 week later) | Discrimination performance (d') was measured during single task performance for each participant by comparing hit (correct responses to target signs) rates and false alarm (responses to non-targets) rates and calculated as d' = Z (hits) - Z (false alarms). Performance data was collected during the single task condition. |
| Multitask Performance Change | Pre-tACS and post-tACS (1 week later) | Discrimination performance (d') was measured while multitasking for each participant by comparing hit (correct responses to target signs) rates and false alarm (responses to non-targets) rates and calculated as d' = Z (hits) - Z (false alarms). Performance data was collected during the multitask condition. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Continuous Performance Test RT Change (Test of Visual Attention / Sustained Attention) | Pre-tACS and post-tACS (1 week later) | Assessment of sustained attention ability using response time (in ms) during the continuous performance test |
| Continuous Performance Test RTV Change (Test of Visual Attention / Sustained Attention) | Pre-tACS and post-tACS (1 week later) | Assessment of sustained attention ability using response time variability (standard deviation of response times in ms) during the continuous performance test |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Verum Stimulation This group will receive 6-Hz tACS
Transcranial alternating current stimulation: Transcranial alternating current stimulation across the prefrontal cortex using electrodes F3 and F4. | 23 |
| Frequency Control This group will receive 1-Hz tACS
Transcranial alternating current stimulation: Transcranial alternating current stimulation across the prefrontal cortex using electrodes F3 and F4. | 24 |
| Total | 47 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Lost to Follow-up | 0 | 1 |
| Overall Study | Protocol Violation | 3 | 3 |
Baseline characteristics
| Characteristic | Verum Stimulation | Frequency Control | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 1 Participants | 1 Participants | 2 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 19 Participants | 19 Participants | 38 Participants |
| Age, Continuous | 25.8 years STANDARD_DEVIATION 4.6 | 24.6 years STANDARD_DEVIATION 4.2 | 25.2 years STANDARD_DEVIATION 4.4 |
| Continuous Performance Task RT | 322 milliseconds STANDARD_DEVIATION 43 | 322 milliseconds STANDARD_DEVIATION 34 | 322 milliseconds STANDARD_DEVIATION 39 |
| Continuous Performance Task RTV | 76 milliseconds STANDARD_DEVIATION 7 | 65 milliseconds STANDARD_DEVIATION 5 | 71 milliseconds STANDARD_DEVIATION 6 |
| Multitasking Cost Performance | 45.8 Percent change STANDARD_DEVIATION 0.4 | 40.5 Percent change STANDARD_DEVIATION 0.22 | 43.2 Percent change STANDARD_DEVIATION 0.31 |
| Multitask performance | 1.03 d' STANDARD_DEVIATION 0.63 | 1.20 d' STANDARD_DEVIATION 0.58 | 1.12 d' STANDARD_DEVIATION 0.6 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 3 Participants | 4 Participants | 7 Participants |
| Race (NIH/OMB) Black or African American | 1 Participants | 2 Participants | 3 Participants |
| Race (NIH/OMB) More than one race | 1 Participants | 2 Participants | 3 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 15 Participants | 12 Participants | 27 Participants |
| Region of Enrollment United States | 20 Participants | 20 Participants | 40 Participants |
| Sex: Female, Male Female | 12 Participants | 13 Participants | 25 Participants |
| Sex: Female, Male Male | 8 Participants | 7 Participants | 15 Participants |
| Single Task Performance | 1.73 d' STANDARD_DEVIATION 0.63 | 2.01 d' STANDARD_DEVIATION 0.63 | 1.87 d' STANDARD_DEVIATION 0.63 |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 23 | 0 / 24 |
| other Total, other adverse events | 1 / 23 | 2 / 24 |
| serious Total, serious adverse events | 0 / 23 | 0 / 24 |
Outcome results
Primary
Multitasking Performance Cost (Neuroracer Performance Change From Baseline)
Assessment of multitasking ability using change from baseline scores in d' cost (metric of discriminability). Discrimination performance (d') was measured for each participant by comparing hit (correct responses to target signs) rates and false alarm (responses to non-targets) rates and calculated as d' = Z (hits) - Z (false alarms). d' cost was then calculated as the ratio of d' during single task target discrimination task to multitask target discrimination, expressed as percentage cost.
Time frame: Pre-tACS and post-tACS (1 week later)
Population: Only data from participants who completed the full protocol were analyzed
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Verum Stimulation | Multitasking Performance Cost (Neuroracer Performance Change From Baseline) | 45.3 percentage change of d' | Standard Deviation 0.31 |
| Frequency Control | Multitasking Performance Cost (Neuroracer Performance Change From Baseline) | 37.9 percentage change of d' | Standard Deviation 0.27 |
p-value: 0.55ANCOVA
Primary
Multitask Performance Change
Discrimination performance (d') was measured while multitasking for each participant by comparing hit (correct responses to target signs) rates and false alarm (responses to non-targets) rates and calculated as d' = Z (hits) - Z (false alarms). Performance data was collected during the multitask condition.
Time frame: Pre-tACS and post-tACS (1 week later)
Population: Only data from participants who completed the full protocol were analyzed
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Verum Stimulation | Multitask Performance Change | 1.17 d' | Standard Deviation 0.76 |
| Frequency Control | Multitask Performance Change | 1.79 d' | Standard Deviation 0.89 |
p-value: 0.03ANCOVA
Primary
Single Task Performance Change
Discrimination performance (d') was measured during single task performance for each participant by comparing hit (correct responses to target signs) rates and false alarm (responses to non-targets) rates and calculated as d' = Z (hits) - Z (false alarms). Performance data was collected during the single task condition.
Time frame: Pre-tACS and post-tACS (1 week later)
Population: Only data from participants who completed the full protocol were analyzed
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Verum Stimulation | Single Task Performance Change | 1.99 d' | Standard Deviation 0.94 |
| Frequency Control | Single Task Performance Change | 2.70 d' | Standard Deviation 1.07 |
p-value: 0.02ANCOVA
Secondary
Continuous Performance Test RT Change (Test of Visual Attention / Sustained Attention)
Assessment of sustained attention ability using response time (in ms) during the continuous performance test
Time frame: Pre-tACS and post-tACS (1 week later)
Population: Only data from participants who completed the full protocol were analyzed
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Verum Stimulation | Continuous Performance Test RT Change (Test of Visual Attention / Sustained Attention) | 300 milliseconds | Standard Deviation 42 |
| Frequency Control | Continuous Performance Test RT Change (Test of Visual Attention / Sustained Attention) | 303 milliseconds | Standard Deviation 31 |
p-value: 0.51ANCOVA
Secondary
Continuous Performance Test RTV Change (Test of Visual Attention / Sustained Attention)
Assessment of sustained attention ability using response time variability (standard deviation of response times in ms) during the continuous performance test
Time frame: Pre-tACS and post-tACS (1 week later)
Population: Only data from participants who completed the full protocol were analyzed
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Verum Stimulation | Continuous Performance Test RTV Change (Test of Visual Attention / Sustained Attention) | 58 milliseconds | Standard Deviation 26 |
| Frequency Control | Continuous Performance Test RTV Change (Test of Visual Attention / Sustained Attention) | 56 milliseconds | Standard Deviation 21 |
p-value: 0.8ANCOVA