Pittsburgh Compound B-Negative Dementia—A Possibility of Misdiagnosis of Patients With Non-Alzheimer Disease-Type Dementia as Having AD

Abstract

Amyloid imaging has been used to detect amyloid deposition in the brain. We performed Pittsburgh compound B (PiB)-positron emission tomography on 63 patients with dementia having cognitive decline or memory disturbance. In addition, we measured the patients' apolipoprotein E4 (apo E4) status and cerebrospinal fluid (CSF) levels of amyloid-β (Aβ)1-42, tau, and P-tau. Finally, the patients were diagnosed as having probable Alzheimer disease (AD) on the basis of their neuropsychological findings and because they met the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association criteria. Among the patients diagnosed with probable AD, 10 patients were PiB negative. The CSF levels of P-tau and tau in PiB-negative patients were significantly lower than those in the PiB-positive patients. In addition, the CSF levels of Aβ1-42 in the PiB-negative patients were significantly higher than those in the PiB-positive patients. None of the PiB-negative patients were apo E4 carriers. These results suggest that the PiB-negative patient group included not only AD patients but also non-AD-type dementia patients. However, our finding is based on a relatively small number of patients and therefore should be replicated in a larger cohort. In addition, it will be necessary to categorize these participants by longitudinal follow-up and postmortem pathological examinations.