We studied the rare case of an older adult with dementia following herpes zoster encephalitis (HZE). This 71-year-old woman presented to us approximately 1 year following resolution of a rapid-onset episode of HZE, and subsequently underwent neuropsychological and neuroimaging examinations. Cognitive assessment revealed impairments in general cognitive functioning, verbal and nonverbal memory, executive functions, speed of information processing, attention/working memory, and motor skills. The patient's neuroimaging data, when compared to a demographically similar healthy control sample (n = 9), demonstrated moderate central and perisylvian brain volume loss, several subcortical lesions in the white matter, and resting state whole brain and hippocampal hypoperfusion. These findings highlight neuropsychological changes evident in a dementia syndrome of this type, and they suggest that early identification and treatment of HZE has implications for the preservation of long-term cognitive functioning.