Which of the following biomarkers is elevated in the cerebrospinal fluid (CSF) of patients with Alzheimer disease (AD)?
(E) Elevations of CSF total tau and phosphorylated tau (P-tau) and a reduction of CSF A[beta]-42 levels are characteristic of AD. Recent studies provide evidence that a reduction in the ratio of A[beta]-42 to P-tau may help distinguish patients with early AD from those with frontotemporal dementia and identify those with mild cognitive impairment who later develop AD. (Hansson, 165–173, 228–234; Schoonenboom, 1580–1584; Schott, 552–558)
Frontotemporal dementia may be associated with
(C) Parkinson disease (PD)
(B) Frontotemporal dementia (FTD) or frontotemporal lobar degeneration (FTLD) is a group of related neurodegenerative conditions that present as a disturbance of behavior or language. A division of FTLD into three subgroups is now widely accepted, particularly since the publication in 1998 of diagnostic consensus criteria. The first subgroup is the frontal or behavioral variant FTD (fvFTD or bvFTD, or confusingly sometimes just FTD), which accounts for about half of FTLD cases. The others are progressive nonfluent aphasia (PNFA) and SD, which often present as a fluent progressive aphasia but are due to a deficit of conceptual knowledge rather than of language. The motor syndromes of corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), and motor neuron disease (MND) may also be associated with FTLD features and pathology; some authorities see these as part of the same spectrum. FTLD has a strong genetic component but only a small proportion of cases show simple Mendelian inheritance. Goldman and colleagues have examined this issue in detail by selecting FTLD pedigrees from their genetic counseling service and stratifying them according to the strength of association of the FTLD syndromes within each pedigree. They found that FTD-MND was the most heritable of the syndromes, although even here only 37% of cases occurred in pedigrees with an autosomal dominant pattern of inheritance while 41% had no family history. Most of the responsible genes in the pedigrees with an apparent single-gene defect could not be identified on screening for recognized mutations, implying that many loci remain to be described. (Goldman, 1817–1819; Knibb, 565–571; Neary, 1546–1554)
Degeneration of the left frontoinsular cortex is prominent in