Early-onset Alzheimer's disease versus frontotemporal dementia: resolution with genetic diagnoses?

abstractWe report a diagnostically challenging case of a 64-year-old man with a history of remote head trauma who developed mild behavioral changes and dyscalculia. He was diagnosed with clinical Alzheimer’s disease (AD), with additional features consistent with behavioral variant frontotemporal dementia. Structural magnetic resonance imaging revealed atrophy in bilateral frontal and parietal cortices and hippocampi on visual inspectionand left frontal pole and bilateral anterior temporal encephalomalacia, suspected to be due to head trauma. Consistent with the diagnosis of Alzheimer’s pathology, positron emission tomography (PET) with Pittsburgh compound Bsuggested the presence of beta-amyloid. FluorodeoxyglucosePET demonstrated hypometabolism in bilateral frontal and temporoparietal cortices. Voxel-based morphometryshowed atrophy predominant in ventral frontal regions (bilateral orbitofrontal cortex, pregenual anterior cingulate/medial superior frontal gyrus), bilateral mid cingulate, bilateral late...