RESUMEN
The present paper describes a series of single-case evaluations of the effects of bromocriptine, a dopamine D2 post-synaptic receptor agonist, in 13 patients with clinical features of abulia. An open trial in seven males and six females who had either traumatic brain injury or subarachnoid haemorrhage between two months and five years previously. After repeated baseline assessments, bromocriptine was administered in gradually increasing doses. Assessments were repeated at increasing doses, during maintenance, and after withdrawal. Some newly developed structured instruments for quantifying motivation were used; measures of anxiety and depression, and cognitive tests sensitive to motivation were also administered. Following bromocriptine treatment improved on all scores measured other than mood. Improvement was maintained after bromocriptine withdrawal in nine of the patients. Abulia in patients with brain injury may result from dysfunction in the mesocorticolimbic dopaminergic circuitry, giving rise to associated deficiencies in reward responsiveness and cognitive function. New rating scales are proposed of motivation in brain injured patients