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Lorca-Puls DL, Gajardo-Vidal A, Mandelli ML, Illán-Gala I, Ezzes Z, Wauters LD, Battistella G, Bogley R, Ratnasiri B, Licata AE, Battista P, García AM, Tee BL, Lukic S, Boxer AL, Rosen HJ, Seeley WW, Grinberg LT, Spina S, Miller BL, Miller ZA, Henry ML, Dronkers NF, Gorno-Tempini ML. Neural basis of speech and grammar symptoms in non-fluent variant primary progressive aphasia spectrum. Brain 2024; 147:607-626. [PMID: 37769652 PMCID: PMC10834255 DOI: 10.1093/brain/awad327] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 07/28/2023] [Accepted: 08/29/2023] [Indexed: 10/03/2023] Open
Abstract
The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) is a neurodegenerative syndrome primarily defined by the presence of apraxia of speech (AoS) and/or expressive agrammatism. In addition, many patients exhibit dysarthria and/or receptive agrammatism. This leads to substantial phenotypic variation within the speech-language domain across individuals and time, in terms of both the specific combination of symptoms as well as their severity. How to resolve such phenotypic heterogeneity in nfvPPA is a matter of debate. 'Splitting' views propose separate clinical entities: 'primary progressive apraxia of speech' when AoS occurs in the absence of expressive agrammatism, 'progressive agrammatic aphasia' (PAA) in the opposite case, and 'AOS + PAA' when mixed motor speech and language symptoms are clearly present. While therapeutic interventions typically vary depending on the predominant symptom (e.g. AoS versus expressive agrammatism), the existence of behavioural, anatomical and pathological overlap across these phenotypes argues against drawing such clear-cut boundaries. In the current study, we contribute to this debate by mapping behaviour to brain in a large, prospective cohort of well characterized patients with nfvPPA (n = 104). We sought to advance scientific understanding of nfvPPA and the neural basis of speech-language by uncovering where in the brain the degree of MRI-based atrophy is associated with inter-patient variability in the presence and severity of AoS, dysarthria, expressive agrammatism or receptive agrammatism. Our cross-sectional examination of brain-behaviour relationships revealed three main observations. First, we found that the neural correlates of AoS and expressive agrammatism in nfvPPA lie side by side in the left posterior inferior frontal lobe, explaining their behavioural dissociation/association in previous reports. Second, we identified a 'left-right' and 'ventral-dorsal' neuroanatomical distinction between AoS versus dysarthria, highlighting (i) that dysarthria, but not AoS, is significantly influenced by tissue loss in right-hemisphere motor-speech regions; and (ii) that, within the left hemisphere, dysarthria and AoS map onto dorsally versus ventrally located motor-speech regions, respectively. Third, we confirmed that, within the large-scale grammar network, left frontal tissue loss is preferentially involved in expressive agrammatism and left temporal tissue loss in receptive agrammatism. Our findings thus contribute to define the function and location of the epicentres within the large-scale neural networks vulnerable to neurodegenerative changes in nfvPPA. We propose that nfvPPA be redefined as an umbrella term subsuming a spectrum of speech and/or language phenotypes that are closely linked by the underlying neuroanatomy and neuropathology.
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Affiliation(s)
- Diego L Lorca-Puls
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Sección de Neurología, Departamento de Especialidades, Facultad de Medicina, Universidad de Concepción, Concepción, 4070105, Chile
| | - Andrea Gajardo-Vidal
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Centro de Investigación en Complejidad Social (CICS), Facultad de Gobierno, Universidad del Desarrollo, Santiago, 7590943, Chile
- Dirección de Investigación y Doctorados, Vicerrectoría de Investigación y Doctorados, Universidad del Desarrollo, Concepción, 4070001, Chile
| | - Maria Luisa Mandelli
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Ignacio Illán-Gala
- Sant Pau Memory Unit, Department of Neurology, Biomedical Research Institute Sant Pau, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, 08025, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Madrid, 28029, Spain
- Global Brain Health Institute, University of California, San Francisco, CA 94143, USA
| | - Zoe Ezzes
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Lisa D Wauters
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Department of Speech, Language and Hearing Sciences, University of Texas, Austin, TX 78712-0114, USA
| | - Giovanni Battistella
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Department of Otolaryngology, Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA 02114, USA
| | - Rian Bogley
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Buddhika Ratnasiri
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Abigail E Licata
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Petronilla Battista
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Global Brain Health Institute, University of California, San Francisco, CA 94143, USA
- Laboratory of Neuropsychology, Istituti Clinici Scientifici Maugeri IRCCS, Bari, 70124, Italy
| | - Adolfo M García
- Global Brain Health Institute, University of California, San Francisco, CA 94143, USA
- Centro de Neurociencias Cognitivas, Universidad de San Andrés, Buenos Aires, B1644BID, Argentina
- Departamento de Lingüística y Literatura, Facultad de Humanidades, Universidad de Santiago de Chile, Santiago, 9160000, Chile
| | - Boon Lead Tee
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Global Brain Health Institute, University of California, San Francisco, CA 94143, USA
| | - Sladjana Lukic
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Department of Communication Sciences and Disorders, Ruth S. Ammon College of Education and Health Sciences, Adelphi University, Garden City, NY 11530-0701, USA
| | - Adam L Boxer
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Howard J Rosen
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - William W Seeley
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Department of Pathology, University of California San Francisco, San Francisco, CA 94143, USA
| | - Lea T Grinberg
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Global Brain Health Institute, University of California, San Francisco, CA 94143, USA
- Department of Pathology, University of California San Francisco, San Francisco, CA 94143, USA
| | - Salvatore Spina
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Bruce L Miller
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
- Global Brain Health Institute, University of California, San Francisco, CA 94143, USA
| | - Zachary A Miller
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
| | - Maya L Henry
- Department of Speech, Language and Hearing Sciences, University of Texas, Austin, TX 78712-0114, USA
- Department of Neurology, Dell Medical School, University of Texas, Austin, TX 78712, USA
| | - Nina F Dronkers
- Department of Psychology, University of California, Berkeley, CA 94720, USA
- Department of Neurology, University of California, Davis, CA 95817, USA
| | - Maria Luisa Gorno-Tempini
- Memory and Aging Center, Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, SanFrancisco, CA 94158, USA
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