Cotard's Syndrome with Preserved Intelligence: Verbalization of a Depersonalization-Nihilistic State and a Deconstruction of the "Delusion" Dogma — A Clinical Case with PET-CT and qEEG Data

This clinical essay presents a single case of a patient with a severe depersonalization-nihilistic state, assessed within the framework of Cotard's syndrome. Unlike classical descriptions, the patient describes her experience in neurophysiological terms: as a disruption of brain systems associated with self-awareness, interoception, and emotional salience. The work proposes the concept of cognitively mediated modulation of Cotard's syndrome to account for the influence of preserved intelligence and scientific vocabulary on the form of clinical presentation. The case is documented with: * PET-CT (¹⁸F-FDG) showing hypometabolism in DMN regions (medial prefrontal cortex, posterior cingulate cortex, precuneus); * quantitative EEG (increased Theta/Beta index, decreased alpha rhythm); * MRI (no structural changes); * laboratory findings (vitamin D deficiency, low ferritin, negative autoimmune panel); * written expert opinions (Professor Steven Laureys, neurologist M. T., and psychiatric assessments). The essay also: * reviews medication-induced Cotard-like states (acyclovir/valacyclovir, cefepime, antipsychotic polypharmacy); * discusses the well-known clinical case of Graham; * includes a comparable descriptive case of another individual (P. V.); * critiques the symptom-centered approach and the diagnostic closure that can follow a psychiatric label; * argues for the integration of biomarkers and instrumental studies in complex, treatment-resistant states; * considers neuromodulatory methods (TMS, ECT) as prospects for treatment. The author is both the subject of the clinical observation and the researcher. All third-party information is presented with consent or anonymized. This is not an independent clinical study, a diagnosis, or a treatment recommendation. It is offered as a clinical observation and hypothesis requiring further verification.