Limbic responsiveness to procaine in cocaine-addicted subjects.
OBJECTIVE
The limbic system plays a critical role in motivation, emotional expression, and memory. The authors investigated whether a state of permanent limbic neuronal hyperexcitability, or sensitization, is present in cocaine addicts as a consequence of repeated cocaine use.


METHODS
Single photon emission computed tomography (SPECT) of regional cerebral blood flow (rCBF) was used to compare the central nervous system response to the limbic stimulus procaine in 10 cocaine-dependent male patients and 10 healthy comparison male subjects.


RESULTS
The cocaine-addicted subjects demonstrated bilateral activation of the orbitofrontal cortex after the procaine challenge, whereas the comparison subjects showed activation of the anterior cingulate, bilateral insular, and right amygdalar regions. After receiving placebo, the cocaine-addicted subjects showed markedly lower rCBF in the bilateral orbitofrontal cortex than the comparison subjects.


CONCLUSIONS
The pattern of hypoperfusion in the placebo state followed by heightened activation with procaine in the cocaine-addicted subjects is similar to the pattern of interictal hypoperfusion and ictal hyperperfusion that has been observed in subjects with epilepsy. The findings for the cocaine-addicted subjects may thus represent evidence of localized (orbitofrontal) sensitization.
Department of Psychiatry, Nuclear Medicine Center, University of Texas Southwestern Medical Center, Dallas, USA. byron.adinoff@utsouthwestern.edu
B
B
Adinoff
M D
MD
Devous
S M
SM
Best
M S
MS
George
D
D
Alexander
K
K
Payne
D000328:Adult; D016739:Behavior, Addictive / Q000000981:diagnostic imaging / Q000523:psychology; D019970:Cocaine-Related Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000523:psychology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007696:Kindling, Neurologic / Q000187:drug effects* / Q000502:physiology; D008032:Limbic System / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D010919:Placebos; D011343:Procaine / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data
D010919:Placebos; D011343:Procaine