Posterior Cingulate Cortex Hypometabolism in Non-Amnestic Variants of Alzheimer's Disease

J Alzheimers Dis. 2020;77(4):1569-1577. doi: 10.3233/JAD-200567.

Abstract

Background: Hypometabolism of the posterior cingulate cortex (PCC) is an important diagnostic feature of late-onset, amnestic Alzheimer's disease (AD) measured with 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). However, it is unclear whether PCC hypometabolism has diagnostic value in young-onset, non-amnestic variants of AD, which exhibit less pathology in the hippocampus and default mode network.

Objective: Evaluate the prevalence and diagnostic value of PCC hypometabolism in non-amnestic variants of AD.

Methods: We retrospectively identified 60 patients with young-onset, atypical dementia who have undergone a detailed clinical evaluation, FDG-PET, and an amyloid biomarker (amyloid-PET or cerebrospinal fluid analysis). We quantitatively analyzed regional hypometabolism in 70 regions of interest (ROI) using the MIMneuro® software.

Results: Based on a cut-off of z-score < -1.5 for significant PCC hypometabolism, the prevalence of PCC hypometabolism in non-amnestic variants of AD was 65% compared to 28% in clinical variants of frontotemporal dementia (FTD). The ROI with the maximal hypometabolism was the dominant middle temporal gyrus in the language variant of AD (mean z score -2.28), middle occipital gyrus in PCA (-3.24), middle temporal gyrus in frontal AD (-2.70), and angular gyrus in corticobasal syndrome due to AD (-2.31). The PCC was not among the 10 most discriminant regions between non-amnestic variants of AD versus clinical variants of FTD.

Conclusion: We conclude that PCC hypometabolism is not a discriminant feature to distinguish non-amnestic variants of AD from clinical variants of FTD-and should be interpreted with caution in patients with young-onset, non-amnestic dementia.

Keywords: Alzheimer’s disease; FDG-PET; non-amnestic variants of AD; posterior cingulate cortex; primary progressive aphasia.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alzheimer Disease / diagnostic imaging*
  • Alzheimer Disease / metabolism*
  • Female
  • Fluorodeoxyglucose F18 / metabolism*
  • Gyrus Cinguli / diagnostic imaging*
  • Gyrus Cinguli / metabolism*
  • Humans
  • Male
  • Middle Aged
  • Positron-Emission Tomography / methods*
  • Retrospective Studies

Substances

  • Fluorodeoxyglucose F18

Grants and funding