89,90 These behavioral deficits could be reversed by administration of apomorphine, a direct dopamine agonist,91,92 and blocked by pretreatment with spiroperidol, a dopamine receptor antagonist.93 Corroborating these observations was the initial report of a patient with akinetic mutism after surgical removal of a tumor from the anterior hypothalamus, who
responded to treatment with the dopamine receptor agonists lergotrile and bromocriptine, but not to carbidopa/L-dopa or methylphenidate, presynaptic dopamine Inhibitors,research,lifescience,medical mimetics.94 This suggested loss of PD0332991 dopaminergic input pointed to anterior cingulate or other corticolimbic structures rather than to the striatum as a cause of the patient’s akinesia. Based on pathological studies of 23 patients, it was subsequently postulated that isolated damage
Inhibitors,research,lifescience,medical to any of the projections of brain stem dopaminergic nuclear groups could result in akinetic mutism.95 Chronic akinetic mutism secondary to mesencephalic infarction, Inhibitors,research,lifescience,medical destroying ventral tegmental area dopaminergic neurons at their site of origin, may also be reversed with dopamine agonists.96,97 In children, akinetic mutism of differing etiologies may respond to bromocriptine with rapid and dramatic improvement, suggesting the same pathogenesis of the disorder in childhood as in adulthood.98 Inhibitors,research,lifescience,medical Response to direct
dopamine agonists may be poor, however, in cases where dopamine receptors have been destroyed – for example, in patients with lesions involving the anterior cingulate gyri. Paralleling the observations in akinetic mutism, a clinically significant and sustained improvement in apathy may be seen with dopaminergic agents in a variety of neuropsychiatrie disorders.99 Effective agents in such conditions may include bromocriptine, amantadine, selegiline, modafinil, Inhibitors,research,lifescience,medical buproprion, amphetamine, and methylphenidate. Dopamine agonists, including bromocriptine and methylphenidate, have been used successfully to treat apathy in patients with anterior communicating artery aneurysm, Wilson’s disease, and human immunodeficiency virus-related dementia.14 In a case of successful methylphenidate Terminal deoxynucleotidyl transferase treatment of apathy secondary to cocaine-related subcortical strokes,100 behavioral improvement was accompanied by an increase in blood flow to the frontal cortex and selective improvement on a reaction time version of the Stroop task. The Stroop interference effect is associated with cerebral activation that is most prominent in frontal and cingulate cortex.101 Apathy is the most commonly observed behavioral disturbance in Alzheimer’s disease, and is associated with anterior cingulate hypoperfusion.