A comprehensive perspective of autistic traits and catatonic symptoms in a patient with Fronto-Temporal Dementia and Bipolar Disorder: a case report

**Background:** Fronto-Temporal Dementia (FTD) is a neurodegenerative disorder with an estimated prevalence of 15–22/100,000, characterized by frontotemporal lobe atrophy leading to behavioral and cognitive changes. Differential diagnosis between FTD and Bipolar Disorder (BD) is challenging because FTD onset often features affective symptoms. Catatonia is frequent in both conditions. Autism Spectrum conditions also show high comorbidity with BD, and subthreshold autistic traits are considered vulnerability factors for mood disorders, mixed episodes, suicidal thoughts, and catatonia.

**Methods:** This is a single case report of a 70-year-old woman (Mrs. X.Y.) with diagnoses of both BD and FTD who presented with catatonic symptoms. The patient's history was obtained from clinical records and caregiver reports. No standardized assessment scales for autistic traits or catatonia were reported.

**Key Results:** The patient exhibited cyclothymic-irritable temperament since adolescence and subthreshold autistic traits since childhood, including difficulties in socio-emotional reciprocity, empathy alterations, strong adherence to routine, and narrow repetitive interests. Despite these traits, she achieved high academic and professional success. At age 20, she developed mood oscillations of both polarities with depressive episodes and episodes of mood elevation, but did not seek treatment. At age 60, following a stressful life event, she experienced progressive worsening of mood, social withdrawal, dysphoria, and aggressive behaviors. At age 62, she developed aphasia; brain MRI and PET showed cortical metabolic changes in frontal and left temporal areas, leading to a diagnosis of Primary Progressive Aphasia and FTD (Semantic Variant). At age 63, she was hospitalized for a mixed episode and diagnosed with BD. From 2015 to 2018, she experienced three additional mood episodes (typically in spring) with progressive worsening. At age 69, she was rehospitalized for a manic episode. In February 2022 (age 70), she was admitted to the authors' clinic with catatonic symptoms including waxy flexibility, grimacing, mutism, negativism, and echolalia. She refused food and hydration, requiring enteral nutrition via nasogastric intubation, temporarily replaced with parenteral nutrition for suspected aspiration pneumonia. She was disoriented and scarcely responsive. The patient was transferred to Intermediate Care and subsequently to a long-term care facility.

**Clinical Implications:** This case supports the hypothesis of a continuum between psychiatric and neurological conditions. The patient's subthreshold autistic traits may have been a vulnerability factor for BD development and later catatonia. The authors note that up to 50% of BD patients may have subthreshold or full-threshold autistic features. A previous study from the authors' group reported that BD patients with subthreshold autistic traits may show earlier BD onset, longer hospital stays, more severe depressive symptoms, rhythmicity alterations, and lifetime suicidality. The case also highlights the intertwined relationship between BD and FTD, where BD may be a prodrome for FTD or FTD may represent a neurodegenerative outcome of BD. The presence of catatonia in this patient aligns with literature showing that 10.4% of individuals with ASD also have catatonia. Shared mechanisms may include alterations in the GABAergic system, neuronal networks, cerebellar structures, and genetic susceptibility on chromosome 15. The authors stress the need for early detection and prevention strategies targeting individuals with subthreshold autistic traits.