Spontaneous low frequency BOLD signal variations from resting-state fMRI are decreased in Alzheimer disease

Samaneh Kazemifar1,2, Kathryn Y Manning1,2, Nagalingam Rajakumar3

  • 1Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.

Plos One
|June 6, 2017
PubMed

Insights

Researchers developed a new resting-state functional MRI (RS-fMRI) metric to measure neuronal activity. This novel indicator effectively differentiates Alzheimer's disease (AD) patients from healthy controls, showing potential for early diagnosis.

Area of Science:

  • Neuroimaging
  • Biomedical Engineering
  • Neurology

Background:

  • Alzheimer's disease (AD) diagnosis relies on identifying altered brain activity, often assessed via functional MRI (fMRI) and PET scans.
  • Existing methods like task-based fMRI, resting-state fMRI (RS-fMRI), and FDG-PET reveal abnormalities in AD patients.
  • A need exists for novel, accessible indicators of neuronal function in AD research.

Purpose of the Study:

  • To introduce and validate a new neuronal activity indicator derived from RS-fMRI textural features.
  • To investigate the relationship between this novel RS-fMRI metric and glucose metabolism measured by FDG-PET.
  • To assess the potential of the RS-fMRI metric in distinguishing between individuals with AD and healthy elderly controls (NEC).

Main Methods:

  • Utilized resting-state functional MRI (RS-fMRI) data from 15 probable AD patients and 15 NEC from the AD Neuroimaging Initiative.
  • Applied independent component analysis (ICA) to RS-fMRI data to identify neuronal components (NC).
  • Quantified regional brain activity using a novel metric based on the variation of the RS-fMRI signal within identified NCs.
  • Measured standardized uptake values relative to the cerebellum (SUVR) from partial volume corrected 18F fluorodeoxyglucose-PET (FDG-PET) images.

Main Results:

  • The novel RS-fMRI brain activity metric was significantly lower in the accumbens of AD patients compared to NEC.
  • Glucose metabolism (SUVR) was significantly reduced in the amygdala and hippocampus of AD patients.
  • A significant positive linear correlation was observed between the RS-fMRI brain activity metric and glucose SUVR measurements.
  • The RS-fMRI activity metric showed preliminary positive correlations with cognitive measures and CSF amyloid β1-42 levels, though not significant after correction.

Conclusions:

  • The novel RS-fMRI derived brain activity metric is a viable indicator of neuronal function.
  • This metric demonstrates the ability to differentiate between individuals with Alzheimer's disease and healthy elderly controls.
  • The findings support the potential of this easy-to-implement RS-fMRI metric as a diagnostic tool in AD research.