Impairment- and activity/participation-directed interventions in progressive language impairment: Clinical and theoretical issues

Background: There is a broad constellation of clinical syndromes in which the most prominent initial and ongoing symptom is deterioration in spoken or receptive language processing, reading, writing, or semantic knowledge. Despite the core language impairments, people with these disorders are likely to be under-referred for speech pathology services (Taylor, Kingma, Croot, & Nickels, 2009 this issue), and there is limited published research on speech pathology interventions in these disorders. Aims: This paper reviews the published impairment- and activity/ participation-directed interventions in semantic dementia and progressive aphasia to determine the current evidence base for clinical decisions about client suitability and selection of treatment goals, methods, and measures. We also identify questions that need to be addressed in future therapy research. Methods & Procedures: We reviewed 15 reports of impairment-directed behavioural, pharmacological, and repeated transcranial magnetic stimulation treatments that implemented some level of experimental control. We reviewed a further 10 reports of interventions generally carried out without experimental control, targeting impairments, activity/participation limitations, education, carer training, or a mixture of these approaches. Outcomes & Results: In the impairment-directed studies almost all participants showed improvement on treated items immediately post-treatment. Improvement was specific to treated items in most word retrieval studies, but there is a possibility that greater generalisation to other items or other language tasks/contexts may have occurred in treatments not targeting naming, and/or for clients with articulatory impairments. Without ongoing practice of therapy activities, treatment gains declined for all participants over a period varying from 2 months to between 6 months and 1 year. There was only one experimentally controlled activity/participation-directed intervention reported for people with progressive language impairments, although other reports of activity/participation-directed interventions described increased communicativeness and communication effectiveness for participants following intervention. Consistent with the aims of activity/participation-interventions, these interventions appear to have a greater impact on everyday communication outside the clinic than impairment-directed interventions, but these impacts need to be investigated and documented. Conclusions: These studies highlight the need for rigorous research design to identify treatment, generalisation, and maintenance effects (Rapp & Glucroft, 2009 this issue), and to identify outcomes that go beyond improvement in the clinic on targeted words, language structures, and behaviours. It is important to tailor interventions closely to individual client needs, involve the spouse/carer in intervention, and ensure that clients have appropriate expectations about therapy. The patterns of therapy gain, limited generalisation, and decline following cessation of therapy activities in impairment-directed studies raise questions about the learning mechanism(s) involved. They also have implications for client suitability, and for choice of therapy items, and therapy delivery and duration.