Creutzfeldt-Jakob disease

A 56-year-old man comes to the PA, accompanied by his partner, for evaluation of “abnormal movements that occur while he sleeps.” Symptoms began around four months ago. According to the partner, the patient has on multiple occasions exhibited various movements, such as throwing a ball or punching invisible objects, while asleep. The partner has been sleeping in the guest bedroom for the past several weeks to avoid getting hurt by him. The patient is unaware of these activities, but he recalls vivid dreams of playing baseball and fighting off home invaders. Past medical history is noncontributory. His temperature is 37.6°C (99.7°F), blood pressure is 138/87 mmHg, and pulse is 17/min. The PA orders a polysomnogram, which reveals REM sleep without atonia. Which of the following findings is this patient likely to develop in the future?