Serum prolactin and response to treatment among cocaine-dependent individuals

Considerable evidence indicates that dopaminergic mechanisms may modulate the central effects of cocaine. We investigated whether basal serum prolactin, a measure of central dopamine activity, differed between cocaine-dependent subjects and controls, and whether prolactin levels among cocaine patients were related to their response to treatment. Eighty-six African-American cocaine-dependent outpatients and 35 African-American controls were studied. Prolactin concentrations in fasting blood samples were assayed by radioimmunoassay. The outcome measures were: number of negative urine drug screens, retention in treatment, counselor ratings of improvement and discharge status. Chi-square tests and independent t-tests were used for data analyses. The basal prolactin(ng/ml) among cocaine patients (9.12 +/- 4.12) was significantly higher compared to controls (7.14 +/- 3.36) (t = 2.52, p < 0.02). Furthermore, the higher prolactin subjects (median prolactin = 7.71) had significantly fewer negative urine screens (p < 0.05) and received less favorable ratings of improvement by counselors (p < 0.01) compared to the lower prolactin group. However, the two groups did not differ significantly in treatment retention (p = 0.13) or discharge status (p = 0.08). The higher basal prolactin among cocaine patients relative to controls may reflect changes in DA activity among cocaine patients. Moreover, higher prolactin seems to be related negatively with certain measures of response to treatment among cocaine patients.