21st June 2023

A 78-year-old man comes into the memory clinic for assessment of memory impairment

A 78-year-old man comes into the memory clinic for assessment of memory impairment. His wife and daughter are with him at the appointment. They report that his ability to concentrate has deteriorated in the last year. However, it is inconsistent, and he has lucid periods. He is more forgetful and more agitated at times. He can be intermittently confused. His wife reports he is often awake, restless in his sleep and distressed at night. One time at night, he mentioned there being their recently lost pet dog in the bedroom, but she assumed this was because he was half asleep and he had just had a dream about their dog. She has also noticed he can be very sleepy and appears to switch off during the day.

What is the most likely underlying diagnosis?