All were right-handed as assessed by the Edinburgh Handedness Inventory ( Oldfield, 1971), and were nonsmokers (of tobacco). ![]() ![]() None had undergone rCBF SPECT examinations or other nuclear medicine procedures before. Based on previous functional imaging studies of anxiety ( Maddock and Buonocore, 1997 Fischer et al, 1996 Liotti et al, 2000 Ketter et al, 1996), we predicted that, relative to placebo, CBD would modulate rCBF in limbic and paralimbic areas: the orbitofrontal, cingulate and medial temporal cortex, and the insula.Ī total of 10 healthy male postgraduate students were studied. We compared the effects of CBD and placebo on resting cerebral regional blood flow (rCBF) in healthy volunteers in a double-blind, cross-over design. In view of its anxiolytic effect, we tested the hypothesis that CBD would affect neural activity in areas that normally mediate anxiety. The aim of the present study was to use functional neuroimaging to investigate this. This is consistent with its anxiolytic effect on anxiety elicited by simulated public speaking ( Zuardi et al, 1993a).Īs the receptors that mediate the psychological effects of CBD are unknown, its mechanism of action on the brain is unclear. CBD may thus possess inherent anxiolytic properties unrelated to THC-type activity. This effect does not seem to involve any pharmacokinetic interactions ( Agurell et al, 1981 Zuardi et al, 1982), and CBD does not bind to the central known cannabinoid receptor, CB 1, ( Bisogno et al, 2001 Mechoulam et al, 2002) and hence cannot be a competitive antagonist ( Howlett et al, 1992). In humans, oral administration of CBD in healthy volunteers attenuates the anxiogenic effect of Δ 9-tetrahydrocannabinol (Δ 9-THC) ( Zuardi et al, 1982). ![]() Using the latter test, anxiolytic effects were also reported for three derivates of CBD, HU-219, HU-252, and HU-291 ( Guimaraes et al, 1994). In particular, in animal studies CBD has effects similar to anxiolytic drugs in conditioned emotional paradigms ( Zuardi and Karniol, 1983), the Vogel conflict test ( Musty et al, 1984), and the elevated plus maze test ( Guimaraes et al, 1990 Onaivi et al, 1990). These results suggest that CBD has anxiolytic properties, and that these effects are mediated by an action on limbic and paralimbic brain areas.Ĭannabidiol (CBD) constitutes up to 40% of Cannabis sativa ( Grlie, 1976) and has quite different psychological effects to the plant's best known constituent, Δ 9-tetrahydrocannabinol (Δ 9-THC) ( Perez-Reyes et al, 1973 Zuardi et al, 1982). There was also a cluster of greater activity with CBD than placebo in the left parahippocampal gyrus ( p<0.001). These included a medial temporal cluster encompassing the left amygdala–hippocampal complex, extending into the hypothalamus, and a second cluster in the left posterior cingulate gyrus. Assessment of brain regions where anxiolytic effects of CBD were predicted a priori revealed two voxel clusters of significantly decreased ECD uptake in the CBD relative to the placebo condition ( p<0.001, uncorrected for multiple comparisons). CBD significantly decreased subjective anxiety and increased mental sedation, while placebo did not induce significant changes. Within-subject between-condition rCBF comparisons were performed using statistical parametric mapping (SPM). ![]() In the second session, the same procedure was performed using the drug that had not been administered in the previous session. The Visual Analogue Mood Scale was applied to assess subjective states. SPECT images were acquired 90 min after drug ingestion. In the first session, subjects were given an oral dose of CBD (400 mg) or placebo, in a double-blind procedure. Each subject was studied on two occasions, 1 week apart. Regional cerebral blood flow (rCBF) was measured at rest using 99mTc-ECD SPECT in 10 healthy male volunteers, randomly divided into two groups of five subjects. The aim of the present study was to investigate this using functional neuroimaging. Animal and human studies have suggested that cannabidiol (CBD) may possess anxiolytic properties, but how these effects are mediated centrally is unknown.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |