Effects of Transcranial Direct Current Stimulation on Tobacco Withdrawal Symptoms

We will recruit 35 non-smokers and 30 adult smokers who smoke > 15 cigarettes/day for more
than two years and are 18-55 years old. We expect about half of them will be females. All
participants will be screened for drugs of abuse and female participants will receive a
pregnancy test. Each smoker will participate in four tDCS sessions, one for sham and three
for real tDCS, each for one set of electrode montage. The first set is dorsal lateral
prefrontal cortex (i.e., F3 and F4 of 10/20 EEG system) and neck. The second set is middle
line prefrontal cortex (Fz), superior parietal cortex (Pz), and bilateral inferior temporal
cortex (T3 and T4). The third set is left dorsal lateral prefrontal cortex (F3) and superior
parietal cortex (P1), and right inferior temporal cortex (T4). The sequence of real and sham
tDCS will be counterbalanced among participants. Each session will last for 20 minutes and
there will be a minimum 48 hours between the two sessions. Participants will be required to
be abstinent from cigarette smoking overnight for a minimum of 10 hours and arrive at our
lab around 8:30 AM for each tDCS session. After arrival, each participant will provide a
breath sample for detection of any alcohol in their system, an assay of CO and for
verification of abstinence from cigarette smoking. We will place a nicotine patch (Nicoderm
with 21 mg nicotine) on the back of participants. We will also ask each participant to chew
a nicotine gum (Nicorette gum with 4 mg nicotine) for 30 minutes. The participants will
perform a battery of computerized tasks including the N-Back working memory task, and an
attention task involving watching a computer screen and pressing buttons to indicate more
odd or even numbers displayed on the screen. In addition participants will complete the
following questionnaires related to mood, nicotine withdrawal, mental state, possible side
effects, and cigarette craving: Profile of Mood States (McNair et al 1971), Shiffman-Jarvik
Withdrawal Scales (Shiffman & Jarvik 1976), and Urge To Smoke (Jarvik et al 2000), tDCS side
effects questionnaire, Wisconsin Smoking Withdrawal Scale (Welsch 1999), Perceived Stress
Scale (Cohen 1983), Spielberger State/Trait Anxiety Questionnaire (Spielberger 1970).

Each participant will repeat above battery of cognitive tasks and questionnaires after tDCS.
Then they will be instructed to smoke one cigarette after this second battery of
tasks/questionnaires, and repeat the second battery of questionnaires after cigarette
smoking.

Inclusion Criteria:

- Good general health

- Age between 18 and 55 yrs

- Smokers must smoke at least 15 cigarettes per day for the past two years (as
indicated by self-report)

- Must give a breath CO sample of at least 15 ppm to verify current tobacco consumption
during screen

- Must give a breath CO sample of 7 or less ppm to verify tobacco abstinence during the
abstinence session

- Cocaine and alcohol patients should meet DSM-IV criteria, and is confirmed after
clinical interview with a structured interview with the SCI-PG and SCID-P.

- Right-handed, as indicated by the Edinburgh Handedness Questionnaire

- Smokers should have no illicit drug use, as indicated by negative results on urine
drug screens of cocaine, methamphetamine, opiates, or benzodiazepines at all sessions

- Smokers should consume less than or equal to 10 standard drinks of alcohol per week
(one standard drink consists of one 12 oz. beer, 6 oz. of wine, or one shot (1.5 oz.)
of hard liquor (80 proof) (as indicated by self-report)

- Absence of any past or current DSM-IV Axis I diagnoses (as verified by the SCID)

- English as a first language (subjects may be bilingual), and able to read and speak
English fluently (as indicated by self-report)

Exclusion Criteria:

- Any medically significant acute or chronic medical condition as indicated by
self-report (significance is determined by the P.I.)

- English as a second language (as indicated by self-report)

- Left-handed or ambidextrous as indicated on the Edinburgh Handedness Questionnaire

- Marijuana use of greater than one joint once per week. The subject's urine must
screen negative at each session, so the subject is instructed to refrain from using
marijuana for the 72 hours prior to each session.

- Pregnant, as indicated by a positive result on the urine pregnancy test given at each
session

- Below normal intelligence (Shipley estimated IQ of 85 or less) as indicated by a
combined score of <45 on the Shipley Institute of Living Scale

- Evidence of head injury involving loss of consciousness for 5 minutes or more and/or
requiring hospitalization (as indicated by self-report)

- Depression, as assessed by the SCID or a score of >18 on the BDI (see appendix)

- Probable childhood ADHD as indicated by a score of >46 on the Wender Utah Rating
Scale and/or by self-report

- Self-report of learning disability or dyslexia

- Current or past use of psychotropic drugs (i.e., any antidepressants, antipsychotics,
psychostimulants (i.e. Ritalin), benzodiazepines (i.e., Valium, Xanax), or use of any
other drugs known to affect cognitive functioning (as indicated by self-report).

- HIV positive (as indicated by self-report)

- Positive TB test (as indicated by self-report)

- For subjects participating in the smoking portion, consumption of more than 10
standard drinks of alcohol per week (see inclusion criteria for description of
standard drink)

- Presence of any past or current DSM-IV Axis I Diagnoses, as verified by the SCID

- Abnormal uncorrected vision or hearing which would affect performance on cognitive
tests (as indicated by self-report)

- Smokers group:

- Has not smoked 15 or more cigarettes per day for a minimum of the past 2 years

- A CO breath sample of <15 ppm during any session (except the abstinence session)

- Presence of a pacemaker, catheter or device implant that might be interfered with by
the current applied during tDCS.

b) Eligibility to participate in the study will be determined by trained research
personnel who will screen potential participants over the phone.

c) Minors are excluded because the study involves cigarette smoking. Participants
over 55 are excluded due to their increased probability of smoking-related and
age-related health problems. Pregnant women or those of childbearing potential who
are not using birth control will be excluded because the studies involve cigarette
smoking and therefore pose a risk to a fetus.