Abulia : The Pathology of "Will" and Dopaminergic Dysfunction in Brain-Injured Patients

Objective -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. Method - 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 . Results - Following bromocriptine treatment improved on all scores measured other than mood. Improvement was maintained after bromocriptine withdrawal in nine of the patients . Conclusion - 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