This 55-year-old left-handed man presented with a 5-year history of progressive behavioral and cognitive decline. Initially, his family noticed he was more withdrawn and irritable. The latter worsened to the point where he exhibited bursts of anger over minor issues. A selective serotonin reuptake inhibitor (SSRI) antidepressant, sertraline, was started and provided moderate benefit. However, over the last two years, he had become distractible, slow in thinking, and increasingly forgetful. These issues affected his performance as an accountant. He had been removed from his responsibilities and assigned to clerical work. He endorsed feeling depressed and anxious. He also complained of a chronic generalized headache, which was moderately relieved by ibuprofen. Before practicing as an accountant, he played rugby professionally for 15 years, retiring at the age of 33. During his career he was knocked unconscious multiple times but reported never having any cognitive or behavioral issues at the time. His father, who also played rugby, was diagnosed with Alzheimer disease at age 65 years.