Investigation of impulsivity in patients on dopamine agonist therapy for hyperprolactinemia: a pilot study

The use of dopamine agonists (DAs) has been associated with increased impulsivity and impulse control disorders in several diseases, including Parkinson's disease. Such an effect of DAs on impulsivity has not been clearly characterized in hyperprolactinemic patients, where DAs are the mainstay of therapy. We studied the effects of DAs on impulsivity in hyperprolactinemic patients treated at a tertiary pituitary center, using validated psychometric tests. Cross-sectional study. Impulsivity was evaluated in 30 subjects, 10 hyperprolactinemic patients on DAs compared to two control groups; one comprising untreated hyperprolactinemic patients (n = 10) and a second group consisting of normoprolactinemic controls with pituitary lesions (n = 10). Measures of impulsivity included both self-report questionnaires as well as laboratory-based tasks. Hyperprolactinemic patients on DAs had a higher score (mean ± SD) in one self-report measure of impulsivity, the attention subscale of the Barratt Impulsiveness Scale (16.2 ± 2.7), as compared to the hyperprolactinemic control group (12.3 ± 2.5) and the normoprolactinemic group (14.7 ± 4.4) (p = 0.04). No statistically significant difference was found between groups with regards to the other impulsivity scales. In the DA-treated group, a correlation was observed between increased impulsivity (as assessed in the Experiential Discounting Task) and higher weekly cabergoline dose (r(2) = 0.49, p = 0.04). The use of DAs in hyperprolactinemic patients is associated with an increase in one aspect of impulsivity. This effect should be further characterized in larger, longitudinal studies.