Effect of semantic and metacognitive rehabilitation in semantic variant primary progressive aphasia: a single-case experimental study

BACKGROUND: The semantic variant of primary progressive aphasia (svPPA), a rare neurodegenerative disorder, leads to anomia due to a progressive loss of word meaning. In the absence of pharmacological treatment, speech therapy is preferred in clinical practice. However, semantic rehabilitation, which has shown beneficial effects in vascular aphasia when used in combination with metacognitive training, is poorly studied in degenerative pathologies and specifically in svPPA. The aim of this study was to assess the effect of semantic therapy combined with metacognitive training on naming performance in persons with svPPA. METHODS: The study followed a Single Case Experimental Design (SCED) methodology with a multiple baseline AB design. Phase A (baseline period with non-specific phonological rehabilitation) lasted for 6-10 weeks, randomly. Phase B (a specific intervention period combining semantic rehabilitation with metacognitive training) lasted 5 weeks. Three 45-minute treatment sessions were carried out per week. Participants' performance of a rapid naming task (RNT) was measured repeatedly during every second session and constitutes the primary endpoint. RESULTS: In this study, 8 participants were included, comprising 6 men and 2 women aged 59 and 72 years with a diagnosis of svPPA. Six out of 8 participants showed a significant improvement in naming performance on trained items on repeated measurement, as a result of the semantic rehabilitation. Two of the 6 participants who showed significant improvement in naming trained items also showed significant improvement in naming untrained items. CONCLUSION: The results show that specific semantic rehabilitation had a beneficial effect on svPPA participants and promise generalization of these effects. TRIAL REGISTRATION: The study was approved by the Ethics Committee for the Protection of Persons on June 22, 2021 (ID-RCB Number: 2021-A01698-33) and was conducted in accordance with the Declaration of Helsinki.