Frontal variant of Alzheimer's disease with asymmetric presentation mimicking frontotemporal dementia: Case report and literature review. Issue 3 (27th January 2020)

• Record Type: Journal Article
• Authors: Li, Cheng‐Hsuan; Fan, Sung‐Pin; Chen, Ta‐Fu; Chiu, Ming‐Jang; Yen, Ruoh‐Fang; Lin, Chin‐Hsien
• Is Part Of: Brain and behavior. Volume 10:Issue 3(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-01-27
• Subjects: behavior variant of frontotemporal dementia -- beta‐amyloid -- biomarkers -- frontal variant of Alzheimer's disease -- positron emission tomography -- tau; Neurology -- Periodicals; Neurosciences -- Periodicals; Psychology -- Periodicals; Psychiatry -- Periodicals; 616.8005
• DOI: 10.1002/brb3.1548
• Languages: English
• ISSNs: 2162-3279

Abstract

Abstract: Introduction: Frontal variant of Alzheimer's disease (fvAD) is a rare nonamnestic syndrome of Alzheimer's disease (AD). Differentiating it from behavior variant of frontotemporal dementia (bvFTD), which has implications for treatment responses and prognosis, remains a clinical challenge. Methods: Molecular neuroimaging and biofluid markers were performed for the index patient for accurate premortem diagnosis of fvAD. The clinical, neuroimaging, and biofluid characteristics of the patient were compared to those reported in previous studies of fvAD from 1999 to 2019. Results: A 66‐year‐old man presented with progressive executive dysfunction, personality and behavioral changes, and memory decline since age 59. He had no family history of neurodegenerative disorders. A stimulus‐sensitive myoclonus was noted over his left upper extremity. Neuropsychological assessment revealed moderate dementia with a Mini‐Mental State Exam score of 10/30 and compromised executive and memory performance. Brain imaging showed asymmetrical atrophy and hypometabolism over the right frontal and temporal areas, mimicking bvFTD. However, we observed increased tau depositions based on 18 F‐labeled T807 Tau PET in these areas and diffusely increased amyloid deposition based on 11 C‐labeled Pittsburgh compound B positron emission tomography (PET). Plasma biomarker measures indicated an AD profile with increased Aβ1‐42 (18.66 pg/ml; cutoff: 16.42 pg/ml), Aβ1‐42/Aβ1‐40 ratio (0.45; cutoff: 0.30), total tau (29.78 pg/ml; cutoff: 23.89 pg/ml), and phosphorylated tau (4.11 pg/ml; cutoff: 3.08 pg/ml). These results supported a diagnosis of fvAD. Conclusions: Our results with asymmetrical presentations extend current knowledge about this rare AD variant. Application of biofluid and molecular imaging markers could assist in early, accurate diagnosis. Abstract : A 66‐year‐old man presented with progressive executive dysfunction, personality and behavioral changes, memory decline, and asymmetric motor symptoms. Brain molecular imaging revealed amyloid and tau retention, which suggest the diagnosis of frontal variant of Alzheimer's disease.