TMS in Primary Progressive Aphasia: Modulation of Brain Networks and Language

Detailed Summary

Primary Progressive Aphasia (PPA) is a progressive syndrome in the family of Alzheimer's disease and related disorders involving devastating language impairments caused by selective neurodegeneration of the brain's language network. Unfortunately, there is no treatment for PPA. An exciting possibility for treatment is non-invasive repetitive transcranial brain stimulation (rTMS), which induces electric currents in degenerating brain networks, making them in some cases more efficient. Therapeutic benefits from rTMS have been demonstrated when it is applied in many sequential sessions. For example, repeated sessions of rTMS to left dorsolateral prefrontal cortex (dlPFC) is approved by the US Food and Drug administration as a treatment for major depressive disorder. With respect to language, high frequency rTMS increases the response rate for picture naming in healthy individuals and in patients with Alzheimer's disease. Further, in a sham controlled study, Cotelli and colleagues demonstrated that in a group of 10 non-fluent PPA patients, high frequency rTMS over the left and right dlPFC improved the percent of correct responses for action naming. When rTMS was applied for five consecutive days in a sham controlled single case study, Finocchiaro and colleagues showed lasting improvements in language (up to 1 week) in a patient with non-fluent PPA. Trebbastoni and colleagues further showed the same lasting improvements in language (up to 1 week) in a patient with logopenic PPA. Recently, in a sham controlled single case study, Bereau and colleagues applied a more intense rTMS protocol for ten consecutive days and demonstrated significant linguistic improvements in a logopenic PPA patient that lasted for 1 month. These studies have contributed valuable insights into the potential use of rTMS in treating the language symptoms of PPA patients.

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