This chapter talks about a 41-year-old man who was referred to memory clinic because of memory loss, poor verbal expression, loss of interest, and blunted response to environment. Cognitive status was evaluated by the mini-mental state examination (MMSE) and a detailed neuropsychological battery for assessment of memory, language and executive function, attention, and concentration. The examination documented moderate dementia with moderate amnesia and dysexecutive syndrome. Neuropsychological tests showed evidence of cognitive impairment of multiple domains, including memory, executive function, and attention and speed of information processing. He received 3-week penicillin therapy at an Infectious Diseases Hospital. During the follow-up check-up 3 months after penicillin therapy, the serum Rapid Plasma Reagin (RPR) was negative. Performance of verbal fluency and color trail making test was improved dramatically, suggesting executive function was restored after anti-syphilitic therapy. The follow-up magnetic resonance imaging (MRI) scan was unaltered compared with the initial visit.