Frontotemporal transcranial direct current stimulation for disorganized speech in schizophrenia: a translational hypothesis

Disorganized speech is a core and functionally disabling feature of schizophrenia, but it remains insufficiently addressed by current treatments. Transcranial direct current stimulation (tDCS) has been mainly investigated in schizophrenia for auditory verbal hallucinations, whereas its potential application to formal thought disorder and discourse disorganization has received little direct attention. We propose the hypothesis that frontotemporal tDCS may represent a plausible translational strategy for targeting disorganized speech in schizophrenia. This proposal is based on three converging lines of evidence: first, disorganized speech has been associated with dysfunction in frontotemporal language-control networks involved in semantic integration, discourse planning, verbal self-monitoring, and executive regulation of speech; second, auditory verbal hallucinations and disorganized speech, although clinically distinct, may partially overlap in mechanisms related to inner speech regulation, verbal monitoring, semantic processing, and impaired top-down control; and third, previous frontotemporal tDCS studies in schizophrenia suggest possible effects not only on hallucination severity but also on language-related and cognitive domains such as verbal fluency, semantic memory, insight, and working memory. The novelty of this proposal lies in reframing frontotemporal tDCS as a symptom-specific and mechanism-driven intervention for discourse-level disorganization rather than as a general treatment for schizophrenia or a simple extension of hallucination-focused protocols. We outline the theoretical basis, limitations, safety considerations, and future clinical approaches needed to test this hypothesis.