Amyloid PET in Dementia Syndromes: A Chinese Multicenter Study

Abstract

Cerebral β-amyloid deposits and regional glucose metabolism assessed by positron emission tomography (PET) are used to distinguish between Alzheimer's disease (AD) and other dementia syndromes. In the present multicenter study, we estimated the prevalence of β-amyloid deposits on PET imaging in a wide variety of dementia syndromes and mild cognitive impairment (MCI) within a memory clinic population. Methods: Of the 1193 consecutive patients with cognitive impairment (CI) who received combined ¹⁸F-AV45 and/or ¹¹C-PIB PET, 960 were diagnosed with AD, 36 with frontotemporal dementia (FTD), 5 with dementia with Lewy bodies (DLB), 144 with MCI, 29with vascular dementia (VaD), 4 with corticobasal syndrome (CBS) and 15 with unclassifiable dementia. Baseline clinical diagnoses were independently established without access to PET imaging results. ApoE genotype analysis was performed in CI patients and 231 gender- and age-matched controls. Results: Of the 1193 CI patients, 860 (72.1%) were amyloid-positive. The prevalence of amyloid positivity in AD and MCI patients was 86.8% (833/960) and 9.7% (14/144), respectively. In FTD patients, the prevalence of β-amyloid deposits was 5.6% (2/36). In the 4 CBS patients, two were amyloid-positive. Three of the 5 DLB patients showed amyloid positivity, as did 6 of the 29 VaD (20.7%) patients. The ApoEε4 allele frequency was significantly increased in amyloid-positive CI patients (30.5%) as compared with other amyloid-negative CI patients (14%) or controls (7.3%). Conclusion: Amyloid imaging may potentially be the most helpful parameter for differential diagnosis in dementia, particularly to distinguish between AD and FTD. Amyloid PET can be used in conjunction with the ApoEε4 allele genetic risk test for amyloid deposits.