Frontal Variant Alzheimer’s Disease or Primary Psychiatric Disorder? A Case Report

<b>Background and Clinical Significance</b>: In our case study, the patient experienced approximately a year-long delay in her diagnosis, where her initial diagnosis was mistakenly a primary psychiatric disorder, resulting in undue stress on her family. The aim of this case study is to raise awareness of frontal variant Alzheimer's dementia (fvAD) and to increase knowledge amongst clinicians about this disorder, its management and the need for long-term follow up in specialized clinics. <b>Case Presentation</b>: In January 2023, a 56-year-old woman first presented with a 4-month history of worsening cognitive symptoms with considerable overlapping mood symptoms. Her Mini-Mental State Examination (MMSE) score was 20/28, whereas her Frontal Assessment Battery (FAB) score was 6/18. Upon neuropsychological evaluation, she demonstrated multidomain cognitive deficits, where impairments were most prominent in executive dysfunction, learning, memory and semantic fluency. There was evidence of progressive neurodegenerative changes, with brain MRI (April 2024) showing predominant bilateral frontal and parietal volume loss, sparing the occipital and temporal lobes. Amyloid positron emission tomography (PET) was diffusely positive. A diagnosis of fvAD (frontal variant Alzheimer's dementia) with BPSD was made. Other differential diagnoses included a major neurocognitive disorder due to multiple etiologies (AD and dementia with Lewy bodies (DLB)), frontotemporal dementia (bvFTD), primary progressive aphasia (PPA) and the psychiatric disorder of pseudodementia secondary to a mood disorder. <b>Conclusions</b>: This case presented significant challenges given the atypical neuropsychological profile and the complexity of the symptom presentation with significant neuropsychiatric overlay. The preliminary research findings underscore the complexity of fvAD, warranting future research using fundamental approaches.