The described clinical characteristics of early-onset Alzheimer's disease (EOAD) are distinct from that of late-onset AD. We reported a patient with atypical EOAD.

A 54-year-old, truck driver developed gradual visuospatial, language and calculation deficits for 3 months. The neuropsychological impairments were extensive. Brain MRI revealed asymmetric atrophy in left medial temporal lobe along with distinct widening of sylvian fissure. (18)F-florbetapir-positron emission tomography (PET) showed a high uptake in the cortex. Further, the profiles of cerebrospinal fluid (CSF) biomarker were compatible with AD.

We diagnosed the patient as EOAD based on the result of biomarker study. Increased Aβ burden was identified through amyloid PET imaging and decreased CSF Aβ level. The high rise of CSF Tau proteins was in agreement with the patient's extensive and rapid cognitive decline. This case report demonstrates the importance of AD biomarker study in confronting early-onset dementia with atypical clinical presentation.