Consensus classification of posterior cortical atrophy.
Crutch SJ., Schott JM., Rabinovici GD., Murray M., Snowden JS., van der Flier WM., Dickerson BC., Vandenberghe R., Ahmed S., Bak TH., Boeve BF., Butler C., Cappa SF., Ceccaldi M., de Souza LC., Dubois B., Felician O., Galasko D., Graff-Radford J., Graff-Radford NR., Hof PR., Krolak-Salmon P., Lehmann M., Magnin E., Mendez MF., Nestor PJ., Onyike CU., Pelak VS., Pijnenburg Y., Primativo S., Rossor MN., Ryan NS., Scheltens P., Shakespeare TJ., Suárez González A., Tang-Wai DF., Yong KXX., Carrillo M., Fox NC., Alzheimer's Association ISTAART Atypical Alzheimer's Disease and Associated Syndromes Professional Interest Area None.
INTRODUCTION: A classification framework for posterior cortical atrophy (PCA) is proposed to improve the uniformity of definition of the syndrome in a variety of research settings. METHODS: Consensus statements about PCA were developed through a detailed literature review, the formation of an international multidisciplinary working party which convened on four occasions, and a Web-based quantitative survey regarding symptom frequency and the conceptualization of PCA. RESULTS: A three-level classification framework for PCA is described comprising both syndrome- and disease-level descriptions. Classification level 1 (PCA) defines the core clinical, cognitive, and neuroimaging features and exclusion criteria of the clinico-radiological syndrome. Classification level 2 (PCA-pure, PCA-plus) establishes whether, in addition to the core PCA syndrome, the core features of any other neurodegenerative syndromes are present. Classification level 3 (PCA attributable to AD [PCA-AD], Lewy body disease [PCA-LBD], corticobasal degeneration [PCA-CBD], prion disease [PCA-prion]) provides a more formal determination of the underlying cause of the PCA syndrome, based on available pathophysiological biomarker evidence. The issue of additional syndrome-level descriptors is discussed in relation to the challenges of defining stages of syndrome severity and characterizing phenotypic heterogeneity within the PCA spectrum. DISCUSSION: There was strong agreement regarding the definition of the core clinico-radiological syndrome, meaning that the current consensus statement should be regarded as a refinement, development, and extension of previous single-center PCA criteria rather than any wholesale alteration or redescription of the syndrome. The framework and terminology may facilitate the interpretation of research data across studies, be applicable across a broad range of research scenarios (e.g., behavioral interventions, pharmacological trials), and provide a foundation for future collaborative work.