Apathy in Rapid Eye Movement Sleep Behaviour Disorder (RBD) is Common - Click for Message

RESULTS OF A STUDY

"A total of 46% of patients with RBD were apathetic, compared with 31% of patients with PD in our sample. Most patients with RBD with depression were apathetic but more than half of apathetic patients were not depressed. The sensitivity of the single Unified Parkinson's Disease Rating Scale screening question was only 33% for mild apathy and 50% for severe apathy.

Apathy is a common and debilitating feature of Parkinson's disease (PD) and dementia with Lewy bodies (DLB - Robin Williams diagnosis), which impacts on the quality of life of both patients and carers. Characterized by pathological lack of motivation, it manifests as a reduction in goal‐directed thoughts and behaviours, with or without emotional blunting. Although it frequently coexists with other neuropsychiatric conditions, such as depression and cognitive impairment, apathy is increasingly recognized as a distinct syndrome with different aspects that are not always present. It is not equivalent to anhedonia, as patients with apathy are still able to enjoy activities if they are prompted to act."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5838543/