We provide an in-depth analysis of language functions in early-treated adults with phenylketonuria (AwPKUs, N = 15–33), as compared to age- and education-matched controls (N = 24–32; N varying across tasks), through: a. narrative production (the Cinderella story), b. language pragmatics comprehension (humour, metaphors, inferred meaning), c. prosody discrimination d. lexical inhibitory control and planning (Blocked Cyclic Naming; Hayling Sentence Completion Test, Burgess & Shallice, 1997). AwPKUs exhibited intact basic language processing (lexical retrieval, phonology/articulation, sentence construction). Instead, deficits emerged in planning and reasoning abilities. Compared to controls, AwPKUs were: less informative in narrative production (lower rate of Correct Information Units); slower in metaphorical understanding and inferred meaning; less accurate in focused lexical-search (Hayling test). These results suggest that i) executive deficits in PKU cannot be explained by an accumulation of lower-order deficits and/or general speed impairments, ii) executive functions engage dedicated neurophysiological resources, rather than simply being an emergent property of lower-level systems.
Bibliographical noteThis is an Accepted Manuscript of an article published by Taylor & Francis Group in Cognitive Neuropsychology on 28 Feb 2018, available online at: http://www.tandfonline.com/10.1080/02643294.2017.1422709
De Felice, S., Romani, C., Geberhiwot, T., Macdonald, A., & Palermo, L. (2018). Language processing and executive functions in early treated adults with phenylketonuria (PKU). Cognitive Neuropsychology. https://doi.org/10.1080/02643294.2017.1422709