OBJECTIVE: The purpose of this study was to assess the functional
significance of ventricle-brain ratio (VBR) in terms of how it might affect
sensitivity to cocaine, an indirect dopamine agonist. METHOD: Relationships
between VBR and subjective responses to acute intravenous cocaine
hydrochloride were examined in 20 male polydrug abusers. Tests were
performed in conjunction with positron emission tomography scans to measure
cerebral glucose metabolism. RESULTS: Subjective measures of effects of
cocaine, including self-report ratings of intensity of the drug effect,
scores on the morphine-benzedrine scale of the Addiction Research Center
Inventory, and several items on visual analogue scales, correlated
negatively with VBR. VBR also differed significantly among subjects who
were grouped according to scores on items ("rush" and "crash") of the
Cocaine-Sensitive Scale (larger VBR in subjects with weaker responses). VBR
was not correlated with cocaine-induced changes in cerebral metabolic rates
for glucose. CONCLUSIONS: Relative insensitivity to the subjective effects
of cocaine in polydrug abusers with ventricle enlargement suggests that
ventriculomegaly may reflect changes in periventricular brain regions that
mediate these effects of cocaine.Abstract Teaser