REM Sleep Behavior Disorder EEG

A 62-year-old man presents to the sleep clinic with a 2-year history of violent nocturnal behaviour during which he punches, kicks, and shouts while asleep. His wife reports he appears to be "acting out his dreams" and has sustained a laceration to her arm during one episode. Polysomnography is performed. The EEG shows normal sleep architecture, but the structure marked **A** in the diagram is identified — persistent submental EMG tone during REM sleep with excessive phasic chin and limb EMG twitches. Which of the following is the most important long-term prognostic counselling point for this patient?