The Effects of Bromocriptine on Attention Deficits After Traumatic Brain Injury

Abstract

To evaluate the effects of bromocriptine on a variety of aspects of attention, ranging from laboratory-based impairment measures to caregiver ratings and work productivity, in individuals after traumatic brain injury. Twelve adults with moderate to severe traumatic brain injury and attention complaints in the postacute phase of recovery were enrolled in a 6-wk double-blind, placebo-controlled, crossover study of bromocriptine, titrated to a dose of 5 mg twice a day. A wide range of attentional measures was administered weekly, including computerized and paper-and-pencil tests of attention, videotaped records of individual work in a distracting environment, real-time observational scoring of attentiveness in a classroom environment, and caregiver and clinician ratings of attentiveness. Data from these 12 participants were used to identify attentional dimensions suggestive of a treatment effect for independent replication. The effects of bromocriptine on 13 previously identified attentional factors and 13 individual performance scores were assessed via the Wilcoxon signed ranks test, using a relaxed probability cutoff of 0.20 to select those to be studied in a larger replication sample. Only two factor scores and one individual score met the cutoff, and all of these showed trends toward worse performance on bromocriptine than on placebo. A more detailed investigation of bromocriptine's effect on divided attention was also conducted, but the previously reported finding of a beneficial effect on this domain was not replicated. Blood pressure was marginally lower on bromocriptine than on placebo. In view of the lack of cognitive benefit and the fact that several participants experienced possible or probable drug side effects, we did not pursue a larger replication at this drug dose. Bromocriptine in a dose of 5 mg, given twice a day to individuals with attentional complaints after TBI, does not seem to enhance attentional skills, and it may be associated with an excess of adverse events. It is not clear whether intermittent dosing or lower doses might confer benefit.