Review Question - QID 210487

A 62-year-old man is brought to his primary care physician by his wife who is concerned about the patient's frequent falls. Approximately 6 months ago, she started noticing that he was walking more slowly than usual. He has fallen more than 6 times in the past month, and she is worried that he will sustain a serious injury if he does not stop falling. The patient is a retired banking executive and was active as a triathlete until the age of 60. He does not smoke and drinks 2-3 alcoholic beverages per day. His family history is notable for normal pressure hydrocephalus in his mother and Alzheimer dementia in his father. His temperature is 97.8°F (36.6°C), blood pressure is 131/81 mmHg, pulse is 68/min, and respirations are 19/min. On exam, his movements appear slowed and forced. He shuffles his feet when he walks. Tone is increased in his upper and lower extremities bilaterally. This patient's condition is most strongly associated with which of the following histologic findings on brain autopsy?