A tale of two tracers

Diagnostic minimalism is common for many practitioners as they evaluate patients with early signs of dementia. No doubt it is the lack of effective disease-modifying treatments that has led many to forsake aggressive diagnostic assessment, or at least to defer it, expecting the disease phenotype eventually to declare itself. In this issue of Neurology®, Rabinovici and colleagues¹ report a comparative study of 2 PET tracers, Pittsburgh compound B (PiB) and fluorodeoxyglucose (FDG), applied to a common clinical problem: patients who develop in their 60s the early signs of impairment that could represent either of the most common forms of dementia, Alzheimer disease (AD) or frontotemporal lobar degeneration (FTLD). The premise underlying this and related research is that early, precise dementia diagnosis is important. Patients, families, and doctors deserve the most accurate information about the disease-causing symptoms; prognostication, education, and planning, as well as symptomatic treatment, equally demand such information. Furthermore, disease-modifying treatment trials will likely be inefficient until we can identify the molecular pathology targeted by the treatment. The Rabinovici et al. report is timely because the diagnostic armamentarium for dementing disorders could soon be substantially augmented by the availability of a new form of molecular imaging, amyloid PET, which will perhaps soon be approved by the Food and Drug Administration. These …