2026 ECNP Congress

PS01-1129

From nihilistic delusions to neurodegeneration: Cotard’s syndrome as a prodromal manifestation of behavioural variant frontotemporal dementia: a case report

Berke Tuğ — H.O. Sonkurt · Eskisehir Osmangazi University Faculty of Medicine, Department of Psychiatry, Eskisehir, Türkiye

2026 ECNP Congress

Introduction

Cotard syndrome is a psychotic disorder characterized by nihilistic delusions in which individuals believe they are dead, their organs have ceased to function, or their bodies are decaying. Historically associated with major depressive disorder and schizophrenia, recent evidence suggests that this syndrome may also emerge as part of neurodegenerative processes such as frontotemporal dementia (FTD). In this case report, we present the clinical course of a patient initially followed with a diagnosis of psychotic depression who was later diagnosed with behavioral variant frontotemporal dementia (bvFTD) after comprehensive evaluation.

Case Presentation

A 55-year-old female, a retired primary school teacher, presented with a four-year history of progressive social withdrawal, apathy, depressive symptoms and functional decline. Her symptoms began with a significant drop in occupational performance—specifically classroom management difficulties—leading to early retirement. During this period, she experienced interpersonal conflicts and a divorce, initially interpreted as reactive triggers. However, social withdrawal worsened, transitioning into profound nihilistic delusions; she claimed death did not exist, her internal organs were empty, and she felt no satiety despite excessive eating. Her premorbid personality was notably active and outgoing.

Previously hospitalized twice for psychotic depression with minimal response to various regimens, her third hospitalization involved venlafaxine (225 mg/day), mirtazapine (15 mg/day), and long-acting aripiprazole (400 mg/month). Neurological examination, EEG, and a previous recent brain MRI were reported as normal. Due to the atypical clinical course, further investigations were conducted to evaluate a possible organic etiology. FDG-PET imaging revealed significant hypometabolism in the bilateral mesial and left lateral temporal regions. Cerebrospinal fluid analysis confirmed a neurodegenerative profile: β-amyloid 1–42 (229 pg/mL), p-tau (25 pg/mL), total tau (98 pg/mL), and neurofilament light chain (NFL) (971 pg/mL). Based on her clinic and new supportive neuroimaging and biomarker findings, a diagnosis of behavioral variant frontotemporal dementia was considered. During outpatient follow-up, urinary and fecal incontinence developed, medication nonadherence persisted, and legal guardianship was established.

Discussion

This case illustrates the diagnostically challenging nature of behavioral variant frontotemporal dementia (bvFTD), which frequently masquerades as a primary functional psychiatric disorder. The emergence of late-onset nihilistic delusions and limited treatment response strongly raised suspicion of an underlying organic etiology, despite a normal structural MRI and EEG.

The clinical progression from early social-occupational decline to impaired self-care and incontinence aligns with the typical progressive course of bvFTD. Significant FDG-PET hypometabolism and highly elevated CSF NFL levels confirmed active neurodegeneration, emphasizing the critical role of biomarkers in atypical psychiatric presentations. Furthermore, metabolic alterations in temporal–limbic networks likely provide the biological substrate for both the nihilistic delusions characteristic of Cotard syndrome and the accompanying behavioral disturbances.

Conclusions

The present case supports the concept of “neurodegeneration under a psychiatric mask” and emphasizes that neurodegenerative disorders should be considered early in the differential diagnosis of late-onset atypical psychiatric presentations. It also demonstrates that normal brain MRI findings do not exclude neurodegenerative processes and underscores the importance of advanced diagnostic tools, including PET imaging and biomarker analyses, in establishing an accurate diagnosis.

References

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