Hemispheric disconnection as a basis for neurodegeneration in apraxia and Alzheimer's disease.

INTRODUCTION: Apraxias, traditionally viewed as executive disorders secondary to focal lesions, are here reformulated as systemic outcomes of progressive interhemispheric disconnection-particularly relevant in the early stages of Alzheimer's disease. OBJECTIVE: To propose an integrated theoretical model that redefines apraxias from a neurosemiotic and embodied perspective, linking them to corpus callosum degeneration and the breakdown of sensorimotor gesture networks. METHODS: This contribution is based on a transdisciplinary conceptual review, integrating data from neuroscience, body semiotics, phenomenology, and recent clinical studies. The reflection is supported by a synthesis of neuroanatomical, cognitive, and behavioral findings regarding proprioceptive function and hemispheric lateralization. MAIN RESULTS: Four forms of apraxia (simple, ideational, ideomotor, and constructive) are distinguished as differential configurations of embodied gesture disintegration. The proposed model links these manifestations to the loss of integration among gesture syntax, proprioceptive semantics, and contextual pragmatics, opening new hypotheses for the early diagnosis of Alzheimer's disease. CONCLUSIONS: Apraxias may be reinterpreted as predictive indicators of early cognitive decline, providing a foundation for the development of more sensitive diagnostic tools and rehabilitation strategies centered on gesture narrative, body memory, and embodied identity.