Evaluation of the effect of transcranial direct current stimulation on language impairments in the behavioural variant of frontotemporal dementia. Issue 2 (29th March 2022)

• Record Type: Journal Article
• Authors: Sanches, Clara; Amzallag, Fanny; Dubois, Bruno; Lévy, Richard; Truong, Dennis Q.; Bikson, Marom; Teichmann, Marc; Valero-Cabré, Antoni
• Is Part Of: Brain communications. Volume 4:Issue 2(2022)
• Publication Date: 2022-03-29
• Subjects: frontotemporal dementia -- language impairment -- transcranial direct current stimulation -- non-invasive neuromodulation -- neurodegenerative diseases; 616
• DOI: 10.1093/braincomms/fcac050
• Languages: English
• ISSNs: 2632-1297

Abstract

Abstract: The behavioural variant of frontotemporal dementia is a neurodegenerative disease characterized by bilateral atrophy of the prefrontal cortex, gradual deterioration of behavioural and executive capacities, a breakdown of language initiation and impaired search mechanisms in the lexicon. To date, only a few studies have analysed the modulation of language deficits in the behavioural variant of frontotemporal dementia patients with transcranial direct current stimulation, yet with inconsistent results. Our goal was to assess the impact on language performance of a single session of transcranial direct current stimulation on patients with the behavioural variant of frontotemporal dementia. Using a sham-controlled double-blind crossover design in a cohort of behavioural frontotemporal dementia patients ( n = 12), we explored the impact on language performance of a single transcranial direct current stimulation session delivering anodal or cathodal transcranial direct current stimulation, over the left and right dorsolateral prefrontal cortex, compared with sham stimulation. A Letter fluency and a Picture naming task were performed prior and following transcranial direct current stimulation, to assess modulatory effects on language. Behavioural frontotemporal dementia patients were impaired in all evaluation tasks at baseline compared with healthy controls. Computational finite element method (FEM) models of cortical field distribution corroborated expected impacts of left-anodal and right-cathodal transcranial direct current stimulation over the dorsolateral prefrontal cortex and showed lower radial field strength in case of atrophy. However, none of the two tasks showed statistically significant evidence of language improvement caused by active transcranial direct current stimulation compared with sham. Our findings do not argue in favour of pre-therapeutic effects and suggest that stimulation strategies evaluating the modulatory role of transcranial direct current stimulation in the behavioural variant of frontotemporal dementia must carefully weigh the influence of symptom severity and cortical atrophy affecting prefrontal regions to ensure clinical success. Abstract : Sanches et al . report no language improvement in frontotemporal dementia after applying transcranial direct current stimulation over dorsolateral prefrontal cortices in a double-blind sham-controlled study. Authors discuss alternative stimulation strategies and patient-customized approaches integrating individual anatomical and functional/clinical features. Graphical Abstract: Graphical Abstract