Pilot Study Repetitive Transcranial Magnetic Stimulation (rTMS) in Cannabis Craving
| Status: | Archived |
|---|---|
| Conditions: | Psychiatric |
| Therapuetic Areas: | Psychiatry / Psychology |
| Healthy: | No |
| Age Range: | Any |
| Updated: | 7/1/2011 |
| Start Date: | August 2009 |
| End Date: | January 2012 |
Background:
- Cannabis, also known as marijuana, is a commonly abused drug. There is no approved
medication to treat cannabis addiction. The desire to use cannabis often increases when
seeing others use it or seeing pictures of it. Researchers are interested in
determining which parts of the brain are active when looking at pictures associated
with cannabis.
- Repetitive transcranial magnetic stimulation (rTMS) uses magnetic pulses to stimulate
the brain. These pulses can change activity in parts of the brain. Researchers are
interested in determining whether rTMS can decrease activity in the parts of the brain
that respond to cannabis, and thereby lessen cravings for cannabis.
Objectives:
- To determine whether transcranial magnetic stimulation can lower craving for cannabis when
people who use cannabis are shown images that increase craving.
Eligibility:
- Individuals 18 years of age and older who are physically healthy and currently use
cannabis (at least 3 times weekly for the past 2 years).
Design:
- The study will involve eight visits over 3 weeks, with each visit lasting 1 to 2 hours.
- Participants will have an initial assessment about cannabis use and provide blood and
urine samples before beginning the study.
- Participants will have three magnetic resonance imaging (MRI) brain scans. The first
MRI scan will look at the structure of the brain at rest. During the other two scans,
participants will look at images related to and not related to cannabis use.
- The rTMS sessions (with either actual TMS or inactive [sham] TMS) will be held daily
for 5 consecutive days. During these testing visits, researchers will ask questions
related to drug use and craving, and collect urine and breath samples for further
study.
- Participants will have two follow-up visits, 1 week and 2 weeks after the rTMS
sessions, to evaluate memory and mood, and one final MRI brain scan at the end of the
study.
Primary objective:
Repetitive transcranial magnetic stimulation (rTMS) provides a non-invasive means of
altering brain neural activity. This pilot study will test whether 5 days of rTMS reduces
cue-induced cannabis craving and use in cannabis users.
Hypothesis:
We predict that active rTMS will significantly lower craving for cannabis compared with sham
rTMS.
Study population:
Thirty healthy adult cannabis users (for at least 2 years, currently averaging 3 times
weekly) with no other major psychiatric disorders except nicotine dependence (DSM IV
criteria) will be recruited from the community.
Design:
Following a baseline phase to evaluate subject characteristics, subjects will be randomly
assigned to receive 5 days of active or sham rTMS. rTMS at 1 Hz and strength 120% of the
motor threshold will be applied to the dorsolateral prefrontal cortex (DLPFC) using a figure
8 coil , beginning 1 second after presentation of a cannabis-associated visual cue and
lasting for 30 seconds. Brain site localization will use a computerized navigation system
based on structural MRI scans obtained before the first session. Each rTMS session (lasting
around 31 minutes) will consist of 54 trials (cue presentations): 36 with
cannabis-associated cues and 9 each with non-drug-associated positive or neutral cues. No
rTMS will be administered with the non-cannabis-associated cues. Subjects return for
follow-up assessments one and two weeks after the final rTMS session.
Outcome measures:
The primary outcome measure will be cannabis craving assessed by the Marijuana Craving
Questionnaire and visual analog scales before and after every rTMS session and at one- and
two-week follow-up. Secondary outcome measures will be self-reported cannabis use and urine
drug testing at each rTMS session and follow-up visit, and changes in regional brain
responses to cannabis-associated visual cues assessed by fMRI done before and after the 5
rTMS sessions.
Benefits:
The future benefit to society may be development of better methods for treatment of cannabis
addiction.
Risks:
The primary risks from rTMS are transient headache, scalp discomfort, decreased spatial
recognition memory, and hearing loss (minimized by wearing ear plugs). Seizures are very
rare when rTMS is administered within accepted safety guidelines and individuals at
increased risk of seizures are excluded. The risk of inducing a manic episode is minimized
by excluding individuals with a history of non-drug-induced mania/hypomania.
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