Motivational deficits after brain injury: effects of bromocriptine in 11 patients.

Abstract

Objective-To test the hypothesis that treatment with bromocriptine would ameliorate deficits in clinical motivation, responsiveness to reward, and frontal cognitive function after brain injury.Method-An open trial in six men and five women who had had either traumatic brain injury or subarachnoid haemorrhage between two months and five years previously. After repeated baseline assessments, bromocriptine was given in gradually increasing doses. Assessments were repeated at increasing doses, during maintenance, and after withdrawal. Novel structured instruments for quantifying motivation were developed; measures of anxiety and depression, and cognitive tests sensitive to motivation or frontal lobe involvement were also given. Results-Bromocriptine treatment was followed by improved scores on all measures other than mood. Improvement was maintained after bromocriptine withdrawal in eight of the patients. Conclusion-Poor motivation in patients with brain injury may result from dysfunction in the mesolimbic/mesocortical dopaminergic circuitry, giving rise to associated deficiencies in reward responsiveness and frontal cognitive function.

Elevated Impulsivity and Impaired Decision-Making in Abstinent Ecstasy (MDMA) Users Compared to Polydrug and Drug-Naïve Controls

“…Furthermore, they were unlikely to result from confounding by the use of other illicit drugs because, after the exclusion of the latter participants, the residual incidence of past use of other illicit drugs was similar between the two drug using groups. Neither is it likely that these results reflect a loss of motivation for financial incentive in the ecstasy users since there were no significant group differences in CARROT (Powell et al, 1996) performance.…”

“…A third composite index of impulsivity, the 'I' score (Salkind and Wright, 1977;Messer and Brodzinsky, 1981), was calculated by subtracting the standard score of the mean latency to first response from the standard score of the total number of errors committed (Z e -Z 1 ). (2) CARROT: Participants were given a computerized version of the Powell et al (1996) CARROT task to provide a behavioral measure of the behavioral responsiveness to small financial incentive. Participants were required to sort computerized cards into categories containing a 1, 2, or 3 as quickly as possible.…”

“…There is some evidence that substance dependence can compromise more general incentive-motivational processing (eg Harris and Aston-Jones, 2003). To determine if cognitive deficits were confounded by reduced motivation, a behavioral measure of responsiveness to financial incentiveFa computerized version of the Card Arranging Reward Responsivity Objective Test (CARROT; Powell et al, 1996) in which participants sort stimuli under conditions of nonreward and rewardFwas employed in the present study. To control for any group differences in premorbid intelligence, we employed the National Adult Reading Test (NART; Nelson, 1982).…”

Smoking, reward responsiveness, and response inhibition: tests of an incentive motivational model

“…Reward responsiveness (acceleration in sorting rate under reward) has been found to correlate highly with measures of executive functioning and with clinical ratings of motivation during rehabilitation in patients with brain injury (Al-Adawi et al 1998); these indices all showed concomitant recovery during a period of treatment with bromocriptine, a dopamine agonist (Powell et al 1996). In a previous study with heavy smokers, reward responsiveness was impaired during abstinence and restored after a single cigarette (Al-Adawi and Powell 1997).…”

“…These predictions are investigated firstly using a behavioural measure of responsiveness to financial incentive, the Card Arranging Reward Responsivity Objective Test (CARROT; Powell et al 1996) in which participants sort cards under conditions of nonreward and reward. Reward responsiveness (acceleration in sorting rate under reward) has been found to correlate highly with measures of executive functioning and with clinical ratings of motivation during rehabilitation in patients with brain injury (Al-Adawi et al 1998); these indices all showed concomitant recovery during a period of treatment with bromocriptine, a dopamine agonist (Powell et al 1996).…”