Acquired stuttering: Exploring behavioural characteristics, response to treatment, and brain changes associated with stuttering.

Arm 1: Comprehensive Behavioural Assessment. Arm 1 has a duration of up to 12 months. Participants will complete three 3-hour assessments over 6-12 months (9 hours total), to explore longitudinal presentation of behavioural characteristics associated with acquired stuttering. Each assessment block will be completed over 2-3 sessions (ideally within a week) with each session lasting no longer than an hour. Assessment will occur at the University of Canterbury Speech and Hearing Clinic or online, and will be administered by qualified Speech-Language Therapists. During assessment, participants will complete a comprehensive case history. Permission will be sought to review medical records (relating to stuttering) and any existing brain images. Clinical speech and language assessments, questionnaires, and observations will evaluate language, speech, cognitive and motor function (as relevant to individual presentation), alongside a thorough assessment of speech fluency. All formal assessments used in the study are published (e.g. Boston Naming Test, Communication Participation Item Bank, Montreal Cognitive Assessment), and are standard practice for speech therapists. Speech fluency will be assessed during conversation, picture description and paragraph reading tasks. Assessments will be completed by qualified members of the study team. Assessment will be individualised depending on the presenting characteristics (e.g. age, underlying neurological condition) of the participant. Arm 2: Systematic Behavioural Treatment for Acquired Stuttering Arm 2 occurs between the first and second assessments in Arm 1. The duration of Arm 2 will be participant-dependent, but is expected to be 2-6 months for most participants. Participants who have completed the initial assessment in Arm 1 and a) have more than 3% stuttered disfluencies and/or b) have concerns about their speech fluency, can choose to receive systematic speech therapy treatment. The aim of the treatment is to limit the impact and severity of the stutter, by helping participants to increase speech fluency, optimise communication, address negative feelings and emotions, and accept any residual fluency disruption. Adherence will be assessed by treatment attendance. Prior to treatment, participants will be asked to complete 1-2 additional assessment sessions (of up to 1 hour) to establish speech fluency baseline. Treatment sessions include the following: a) Discussion of communication successes and challenges b) Assessment of fluency in conversation, picture description and reading tasks c) Practice of fluency modification techniques. Following treatment, participants will complete 2 assessment sessions to monitor treatment effects (Assessment blocks 2 and 3 from Arm 1). Treatment dosage and schedules will be individualised based on presentation and needs. Participants will receive from 1-30 hours speech therapy. Each session will last no longer than 1 hour. Treatment will be provided at the University of Canterbury Speech and Hearing Clinic or online, by qualified speech therapists. All fluency modification techniques used are standard practice in speech therapy (e.g. rhythmic speech, easy-onset), and will be selected based on individual response to trials of different strategies. Adherence will be assessed by monitoring treatment session attendance. Arm 3: Neuroimaging (MRI) study Arm 3 occurs concurrently with Arm 1 and Arm 2, over a 12 month period. A subset of participants from arm 1 and arm 2 will be offered one or more MRI scans. Participants will be randomly selected from Arm 1 and Arm 2 depending on clinical presentation and research need. Scanning will take place at Pacific Radiology, St George's Hospital, in Christchurch. Each scan will take approximately 1 hour and will be conducted by qualified MRI technicians, with results reported by a specialist radiologist. Participants will complete both structural and functional research scans, following our lab's established MRI protocol for studies in stuttering. Participants selected from Arm 1 may complete 1–2 scans, associated with the initial assessment and, if applicable, a follow-up assessment. Participants from Arm 2 may complete 2–3 scans: a pre-treatment scan (which may be the initial assessment scan from Study 1), a post-treatment scan, and, if applicable, a follow-up scan.