NARRATIVE PRODUCTION IN PEOPLE WITH ACQUIRED BRAIN INJURIES: FROM ASSESSMENT TO TREATMENT OPPORTUNITIES

Discourse production is essential for daily communication, supporting emotional expression, storytelling, and social interaction. Its accurate realization relies on a sophisticated system that integrates both articulatory and linguistic processes. People with acquired brain injuries often report difficulties in narrative production as early indicators of their condition and consider discourse restoration a central aim of rehabilitation. The assessment of discourse production provides clinicians with valuable diagnostic information, therapeutic objectives, and tools to monitor recovery. Current clinical practices typically rely on formal tests that evaluate isolated linguistic processes, which limits their ability to capture the complexity of spontaneous speech and the interplay between language and cognition. Concurrently, while behavioural interventions, such as those delivered by Speech and Language Therapists, have demonstrated positive effects on linguistic recovery, novel methods such as transcranial alternating current stimulation (tACS) may provide adjunctive benefits in facilitating rehabilitation of discourse impairments. This thesis reports the results of four studies dealing with assessment and treatment opportunities for narrative production abilities. Study 1 investigated the application of a multilevel discourse analysis to a neurogenic population often overlooked with respect to linguistic alterations: people with multiple sclerosis. Discourse analysis revealed impairments in these patients despite their performance on standardized language tests falling within the normal range. The results indicated deficits at the lexical, grammatical, and discourse levels. Study 2 introduced a Narrative Efficiency Score, which integrated micro- and macro-linguistic variables to evaluate narrative performance. This score was applied to two neurogenic populations differing in the severity of discourse impairments: people with post-stroke aphasia and multiple sclerosis. The Narrative Efficiency Score successfully distinguished between healthy controls and clinical groups, capturing differences in linguistic impairments. It may therefore serve as a useful tool for cross-population comparisons and for monitoring treatment outcomes. Study 3 presented a case study in which a multilevel treatment program was designed and administered to a patient with post-stroke apraxia of speech and aphasia. This integrated approach reflected the complex and interactive nature of language function, encompassing articulation, lexical retrieval, sentence processing, and discourse organization as interdependent components of communicative performance. The therapeutic activities were tailored to the patient’s specific needs and described in detail. Study 4 reported a scoping review on the application of transcranial alternating current stimulation (tACS) in clinical linguistic research. The review addressed the use of tACS both as an adjunct to speech and language therapy and within experimental studies on healthy adults. It highlighted key issues in the current state of knowledge and outlined directions for future research. Overall, the research presented in this thesis focused on discourse production in neurogenic clinical populations, emphasising the importance of assessing and treating narrative disorders. It sought to improve the current knowledge on the assessment and rehabilitation of narrative abilities through linguistic procedures of discourse analysis and updated behavioural and neuromodulation approaches.