Cerebral glucose metabolism and D2/D3 receptor availability in young adults with cannabis dependence measured with positron emission tomography.
BACKGROUND
Cannabis users have been reported to have decreased regional cerebral glucose metabolism after short periods of abstinence. The purpose of this study was to measure striatal dopamine receptor (D2/D3) availability and cerebral glucose metabolism with positron emission tomography (PET) in young adults who had a prolonged exposure to cannabis and who had been abstinent for a period of at least 12 weeks.


METHODS
Six 18-21-year-old male subjects with cannabis dependence in early full remission and six age- and sex-matched healthy subjects underwent PET scans for D2/D3 receptor availability measured with [C11]-raclopride and glucose metabolism measured with [18F]-FDG. All subjects were sober for at least 12 weeks before PET scan procedures. PET data were analyzed with statistical parametric mapping software (SPM99; uncorrected p < 0.001, corrected p < 0.05 at the cluster level). Toxicology screening was performed prior to the PET scan to confirm the lack of drugs of abuse.


RESULTS
Striatal D2/D3 receptor availability did not differ significantly between groups. Compared to controls, subjects with cannabis dependence had lower normalized glucose metabolism in the right orbitofrontal cortex, putamen bilaterally, and precuneus. There were no significant correlations between striatal D2/D3 receptor availability and normalized glucose metabolism in any region of the frontal cortex or striatum.


CONCLUSIONS
These findings may reflect both cannabis exposure and adaptive changes that occur after a prolonged period of abstinence. Subsequent studies should address whether metabolic and dopamine receptor effects are associated with either active use or longer-term withdrawal in these relatively young subjects.
Sevy
Serge
S
The Zucker Hillside Hospital, North Shore-Long Island Jewish Health System, NY 11004, USA. Sevy@lij.edu
Smith
Gwenn S
GS
Ma
Yilong
Y
Dhawan
Vijay
V
Chaly
Thomas
T
Kingsley
Peter B
PB
Kumra
Sanjiv
S
Abdelmessih
Sherif
S
Eidelberg
David
D
D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D003342:Corpus Striatum / Q000000981:diagnostic imaging*; D004292:Dominance, Cerebral / Q000502:physiology; D019788:Fluorodeoxyglucose F18; D005625:Frontal Lobe / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000000981:diagnostic imaging* / Q000534:rehabilitation; D010296:Parietal Lobe / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D020891:Raclopride; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012016:Reference Values
D001786:Blood Glucose; D017448:Receptors, Dopamine D2; D019788:Fluorodeoxyglucose F18; D020891:Raclopride