tDCS Effects on Resisting Smoking: Dose Ranging Study

This trial will use a between-subject single blind design in which participants will be
randomized to one of three tDCS dosage groups (1mA, 2mA or sham) and will receive three 20
minute sessions of the same dosage over the course of 1 week before completing a 7 day quit
attempt. Eligible participants will complete an Intake Visit (week -1) for final eligibility
determination, and complete baseline measures (if eligible). Participants will then be
randomly assigned to one of the three dosage groups (1mA, 2mA or sham) and will attend three
identical tDCS resist-smoking sessions (study days 1, 3, & 5) during which they will receive
20 minutes of their assigned tDCS dosage and complete cognitive tasks and a resist smoking
paradigm. During the resist smoking sessions, participants will receive a session of their
assigned dosage of tDCS for 20 minutes while being exposed to in vivo smoking cues (their
cigarette pack, cigarettes, an ashtray). Participants will not be informed of their dosage
condition. During and after the tDCS session, participants will have the opportunity to smoke
in the approved smoking lab. The investigators will measure time to first cigarette and
subsequent ad libitum smoking during the resist smoking paradigm. Following Session 3
participants will receive a 20 minute coaching session from a trained smoking cessation
counselor to help them prepare for a 7-day quit attempt. During the 7-day quit attempt
participants will be asked to attend 4 monitoring visits (study days 6, 8, 10 & 12) to
confirm smoking status.

Inclusion Criteria:

1. Healthy males and females who are between 18 and 60 years of age

2. Report smoking at least 10 cigarettes per day for the past year and have a CO value of
> 10ppm at intake

3. Planning to live in the area for at least the next 2 months;

4. Capable of giving written informed consent, which includes compliance with the
requirements and restrictions listed in the combined consent and HIPAA form;

5. Able to communicate fluently in English (speaking, writing, and reading);

6. Smokers who answer yes on a question regarding motivation to quit smoking.

Exclusion Criteria:

Alcohol/Drugs:

1. History or current diagnosis or treatment for alcohol or drug abuse (as reported
during phone screen);

2. Positive breath alcohol concentration test (BrAC >0.01) at any study visit. a.
Participants testing positive for breath alcohol with a reading equal to or greater
than .08 (the legal driving limit) or who are visibly impaired will be instructed not
to drive themselves home after the appointment. If a participant needs to use a phone
to call for a safe ride home, an office telephone will be made available to the
participant.

Medication:

Current use or recent discontinuation (within the last 14 days at the time of Intake) of:

1. Smoking cessation medication (e.g., Zyban, Wellbutrin, Wellbutrin SR, Chantix);

2. Anti-psychotic medications;

3. Nicotine replacement therapy (NRT);

4. GABAergic medications;

5. Glutamatergic medications;

6. Any medication that could compromise participant safety as determined by the Principal
Investigator and/or Study Physician.

Daily use of:

7. Opiate-containing medications for chronic pain;

8. Benzodiazepines.

Medical/Neuropsychiatric:

1. Women who are pregnant, planning a pregnancy, and/or breast feeding. All female
subjects will complete a urine pregnancy test at the intake visit and preceding all
brain stimulation sessions (4 urine pregnancy tests in total);

2. History of epilepsy or a seizure disorder;

3. History of stroke;

4. Self-reported history of brain or spinal tumor;

5. Self-reported history or current diagnosis of psychosis, including schizophrenia,
mania, bipolar disorder, major depression (subjects with a history of major depression
but in remission for past 6 months are eligible).

tDCS-related:

1. Self-report of metallic objects in the face or head other than dental apparatus (e.g.
braces, fillings, and implants);

2. Self-report of pacemakers or implantable cardioverter-defibrillator (ICD).

3. Self-report of any skull fracture or opening.

General Exclusion:

1. Any medical condition, illness, disorder, or concomitant medication that could
compromise participant safety or treatment, as determined by the Principal
Investigator;

2. Low or borderline intellectual functioning - determined by a score of less than 90 on
the Shipley Institute of Living Scale (SILS) (administered at Intake Visit). The SILS
correlates with the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Estimated IQ
Test;

3. Inability to provide informed consent or complete any of the study tasks as determined
by the Principal Investigator.