Apathy and Parkinson's disease.

Apathy, a frequent finding in Parkinson's disease (PD), is significantly associated with depression and dementia. Few studies have examined the efficacy of psychotropic or psychological treatments of apathy in PD, and adequate randomized controlled trials are still lacking. There is anecdotal evidence that dopaminergic agonists may be a useful treatment modality. Levodopa may improve the loss of motivation in the "off" motor state, and dopaminergic agonists could be useful to treat apathy after the withdrawal of dopaminergic treatment in patients undergoing deep brain stimulation of the subthalamic nucleus. On the other hand, the selective norepinephrine reuptake inhibitor atomoxetine did not demonstrate efficacy in improving apathy in a randomized controlled trial with apathy as a secondary efficacy measure. Given the significant association between apathy and both depression and cognitive decline, future studies should examine whether improving mood and cognition may also have a positive impact upon apathy in PD. For those PD patients with "pure" apathy, specific psychotherapeutic techniques should be developed.