The language disorder of prion disease is characteristic of a dynamic aphasia and is rarely an isolated clinical feature

• Published in: PloS one 2018-01, Vol.13 (1), p.e0190818-e0190818
• Main Authors: Caine, Diana, Nihat, Akin, Crabb, Philippa, Rudge, Peter, Cipolotti, Lisa, Collinge, John, Mead, Simon
• Format: Article
• Language: English
• Subjects: Aphasia; Aphasia - complications; Biology and Life Sciences; Case-Control Studies; Classification; Cognitive ability; Complications and side effects; Creutzfeldt-Jakob disease; Dementia; Diagnosis; Diagnostic systems; Diseases; Disorders; Female; Health aspects; Hospitals; Humans; Language; Language disorders; Language Tests; Male; Medical diagnosis; Medicine and Health Sciences; Middle Aged; Mutation; Neurology; Neuropsychological Tests; Neuropsychology; Neurosurgery; Paralysis; Prion diseases; Prion Diseases - complications; Progressive supranuclear palsy; Prospective Studies; Proteins; Risk factors; Semantics; Signs and symptoms; Social Sciences; Subgroups
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0190818

Akinetic mutism is a key diagnostic feature of prion diseases, however, their rapidly progressive nature makes detailed investigation of the language disorder in a large cohort extremely challenging. This study aims to position prion diseases in the nosology of language disorders and improve early clinical recognition. A systematic, prospective investigation of language disorders in a large cohort of patients diagnosed with prion diseases. 568 patients were included as a sub-study of the National Prion Monitoring Cohort. All patients had at least one assessment with the MRC Scale, a milestone-based functional scale with language and non-language components. Forty patients, with early symptoms and able to travel to the study site, were also administered a comprehensive battery of language tests (spontaneous speech, semantics, syntax, repetition, naming, comprehension and lexical retrieval under different conditions). 5/568 (0.9%) patients presented with leading language symptoms. Those with repeated measurements deteriorated at a slower rate in language compared to non-language milestones. Amongst the subgroup of 40 patients who underwent detailed language testing, only three tasks-semantic and phonemic fluency and sentence comprehension-were particularly vulnerable early in the disease. These tasks were highly correlated with performance on non-verbal executive tests. Patients were also impaired on a test of dynamic aphasia. These results provide evidence that the language disorder in prion disease is rarely an isolated clinical or cognitive feature. The language abnormality is indicative of a dynamic aphasia in the context of a prominent dysexecutive syndrome, similar to that seen in patients with the degenerative movement disorder progressive supranuclear palsy (PSP).