Default mode network connectivity in stable vs progressive mild cognitive impairment
Jeffrey R. Petrella, Forrest Sheldon, Steven E. Prince, Vince D Calhoun, P. Murali Doraiswamy
Neurology January 13, 2011 DOI: 10.1212/wnl.0b013e31820af94e (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Cross-sectional Peer reviewed |
|---|---|
| Sample size | 68 |
| Population | Elderly subjects: normal controls, mild cognitive impairment, and Alzheimer disease |
| Duration | 2.4 years (±0.8) follow-up |
| Topics | Default mode network |
| Keywords | Cardiology Audiology Clinical dementia rating Cognition Montreal cognitive assessment Alzheimer's disease Cognitive decline |
| Citations | 291 |
| Key findings | Default mode network connectivity indices distinguish MCI patients who progress to AD from those who remain stable, but offer no additional predictive value beyond baseline delayed recall. |
Abstract
Objective: Dysfunction of the default mode network (DMN) has been identified in prior cross-sectional fMRI studies of Alzheimer disease (AD) and mild cognitive impairment (MCI); however, no studies have examined its utility in predicting future cognitive decline.
Methods: fMRI scans during a face-name memory task were acquired from a cohort of 68 subjects (25 normal control, 31 MCI, and 12 AD). Subjects with MCI were followed for 2.4 years (±0.8) to determine progression to AD. Maps of DMN connectivity were compared with a template DMN map constructed from elderly normal controls to obtain goodness-of-fit (GOF) indices of DMN expression. Indices were compared between groups and correlated with cognitive decline.
Results: GOF indices were highest in normal controls, intermediate in MCI, and lowest in AD (p < 0.0001). In a predictive model (that included baseline GOF indices, age, education, Mini-Mental State Examination score, and an index of DMN gray matter volume), the effect of GOF index on progression from MCI to dementia was significant. In MCI, baseline GOF indices were correlated with change from baseline in functional status (Clinical Dementia Rating-sum of boxes) (r = -0.40, p < 0.04). However, there was no additional predictive value for DMN connectivity when baseline delayed recall was included in the models.
Conclusions: fMRI connectivity indices distinguish patients with MCI who undergo cognitive decline and conversion to AD from those who remain stable over a 2- to 3-year follow-up period. Our data support the notion of different functional brain connectivity endophenotypes for "early" vs "late" MCI, which are associated with different baseline memory scores and different rates of progression and conversion.