OBJECTIVE: The authors investigated changes in brain function associated
with cocaine dependence and withdrawal to provide clues regarding the
processes that lead to the uncontrollable self- administration of cocaine.
METHOD: They measured regional brain metabolism with
[18F]-fluorodeoxyglucose (FDG) and positron emission tomography in 15
outpatients with the diagnosis of cocaine abuse and 17 normal comparison
subjects. Ten of the patients were studied less than 1 week after they had
last had cocaine, and five were studied 2-4 weeks after withdrawal.
RESULTS: Patients studied within 1 week of cocaine withdrawal but not those
studied within 2-4 weeks of cocaine withdrawal had higher levels of global
brain metabolism as well as higher levels of regional brain metabolism in
the basal ganglia and orbitofrontal cortex than did normal subjects,
probably as a consequence of less brain dopamine activity. There was also a
significant relationship between the number of days since cocaine
withdrawal and regional brain glucose metabolism in the orbitofrontal
cortex and in the basal ganglia, and the correlations between cocaine
craving and metabolic activity were significant in the prefrontal cortex
and the orbitofrontal cortex. CONCLUSIONS: Although the time-dependent fall
in metabolic activity suggests that the higher metabolic activity observed
less than a week after cocaine withdrawal may represent a nonspecific
expression of drug withdrawal, the selectivity of changes in glucose
metabolism for the basal ganglia and for the orbitofrontal cortex suggests
that the regional metabolic changes seen in cocaine abusers during
detoxification are related to changes in brain dopamine activity.