3. Umbruch 4.4..2005 - Online Pot

Cannabinoids and anxiety 145
Crippa et al. [20] investigated CBD’s effects on regional cerebral blood in
normal postgraduate students. In addition, they administered the VAMS. Each
subject was tested twice, 1 week apart. On week 1, half the subjects were given
a single dose of 400 mg of CBD in corn oil (in a capsule) and the other subjects
received a placebo capsule of corn oil only. On week 2 this procedure was
reversed. During the regional cerebral blood scanning procedure subjects were
resting for 30 min before the VAMS was administered. At the 30-min mark an
intravenous cannula was inserted to administer the radioactive tracer material
and the VAMS was given again. The cannula was removed and the scan was
performed. The VAMS was given again at 60 and 75 min after drug ingestion.
Anxiety decreased significantly by 60 and 75 min, when orally administered
doses of CBD are known to be at peak blood levels. Tracer uptake in the CBD
condition increased relative to placebo in the left parahippocampal gyrus and
the left fusiform gyrus compared with placebo. Tracer uptake decreased in the
CBD relative to placebo in the left amygdala-hippocampal complex and uncus,
the hypothalamus and left superior portion of the posterior cingulate gyrus.
It seems clear that CBD decreased anxiety, which is often observed in people
undergoing SPECT (single-photon emission computed tomography) or
PET (positron emission tomography) scanning as measured by the VAMS. The
brain area which showed increased activity in relation to placebo was the left
parahippocampal gyrus. Deactivation of this area of the brain has been associated
with panic attacks induced by lactate, anxiety induced by combat-related
images and autobiographical memory scripts. It seems that anxiety is associated
with reduced parahippocampal activity, consistent with the findings that
CBD increases activity in this brain area. Because activity in the CBD condition
decreased relative to the placebo, these data fit well since there are a lot
of data linking amygdala activation in a large variety of anxiety states.
Similarly, the hypothalamus is involved in various anxiety states: imaging
studies in particular have shown increases in hypothalamic activity in anxiety
induced in normal volunteers and panic patients, again consistent with the anxiolytic
effect of CBD. In regard to the posterior cingulate gyrus, increased
brain activity is associated with viewing anxiety-provoking videos, which provoked
obsessions in obsessive patients. Patients with obsessive-compulsive
disorder (OCD), if untreated, have increased metabolism in the brain area,
which decreases with treatment and symptom remission, although there are
some conflicting data (see [20] for references relating to all of the above discussion).
While these data might be considered preliminary, they provide the
first evidence of brain systems that are affected in humans. There seems to be
quite strong convergence between animal research and human research, suggesting
strongly that CBD is a true anxiolytic. Given the fact that this drug has
no psychoactivity in terms of intoxication and is very safe, it seems important
to pursue the potential of CBD, with further behavioral pharmacological studies,
mechanistic studies employing neuropharmacological methods and in
clinical studies.