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Original Contribution
March 2011

Temporoparietal Hypometabolism in Frontotemporal Lobar Degeneration and Associated Imaging Diagnostic Errors

Author Affiliations

Author Affiliations: Departments of Neurology (Drs Womack, Diaz-Arrastia, and Lipton) and Psychiatry (Drs Womack and Lipton), University of Texas Southwestern Medical Center at Dallas; Department of Psychiatry, University of Pittsburgh, Pittsburgh (Drs Aizenstein and DeKosky), and Departments of Psychiatry (Dr Arnold) and Neurology (Drs Arnold and Clark), University of Pennsylvania, Philadelphia; Neurology Service, Department of Veterans Affairs Medical Center (Drs Barbas, Turner, and Heidebrink), and Departments of Neurology (Drs Barbas, Turner, and Heidebrink) and Radiology (Dr Koeppe), University of Michigan, Ann Arbor; Department of Neurology, Mayo Clinic, Rochester, Minnesota (Dr Boeve); Department of Neurology, University of California at Davis, Sacramento (Dr DeCarli), Departments of Neuroscience and Public Health, University of California at Berkeley, Berkeley (Dr Jagust), and Departments of Neurology and Neurobiology and Behavior, University of California at Irvine, Irvine (Dr Kawas); Departments of Neurology (Dr Leverenz) and Psychiatry and Behavioral Sciences (Drs Leverenz and Peskind), University of Washington, and Seattle Children's Hospital and Regional Medical Center (Dr Higdon), Seattle; Center for Alzheimer's Care, Imaging, and Research and Department of Neurology, University of Utah, Salt Lake City (Drs Zamrini and Foster); Department of Neurology, Duke University, Durham, North Carolina (Dr Burke); Department of Neurology, Indiana University, Indianapolis (Dr Farlow); and Department of Political Science, Washington University, St Louis, Missouri (Dr Gabel). Dr DeKosky is now with the School of Medicine, University of Virginia, Charlottesville. Dr Lipton is now with the Department of Neurology, Presbyterian Hospital, Dallas.

Arch Neurol. 2011;68(3):329-337. doi:10.1001/archneurol.2010.295

Frontotemporal lobar degeneration (FTLD) is the third most common degenerative dementia, behind Alzheimer disease (AD) and dementia with Lewy bodies.1 It is a heterogeneous disorder with at least 3 recognized clinical presentations,2 multiple histopathologic subtypes,3,4 and familial cases associated with mutations in 4 different genes5-9 with an additional genetic linkage on chromosome 9p.10-12

Despite the existence of consensus clinical diagnostic criteria, patients with FTLD are commonly misdiagnosed as having AD or a psychiatric illness.2,13-15 These mistakes are understandable given the insidious, progressive nature of both FTLD and AD and their shared symptoms.16 Both illnesses may have prominent behavioral changes, which can overlap symptoms typically seen in psychiatric disorders.17-19 While amnesia as the initial symptom of a progressive dementing disease strongly favors a diagnosis of AD, it also occurs in some patients with FTLD.20 Frontotemporal lobar degeneration may present with language deficits, but prominent language deficits also occur in AD.2,21-24 The difficulty in obtaining a detailed and reliable clinical history in some situations is a further challenge to accurate diagnosis and highlights the value of validated diagnostic biomarkers.