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Age and hippocampal volume predict distinct parts of default mode network activity

Matteo De Marco, Sebastien Ourselin, Annalena Venneri

Scientific Reports November 5, 2019 DOI: 10.1038/s41598-019-52488-9 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Observational study using linear regression models on existing datasets Peer reviewed
Sample size 312
Population Healthy adults and patients, including individuals with Alzheimer's disease
Topics Default mode network
Key findings Age at scan significantly predicted default-mode network strength in posterior cingulate/retrosplenial cortex and precuneus, but hippocampal volume did not. Hippocampal volume was positively associated with default-mode connectivity in the right temporo-parietal junction. The authors argue that posterior default-mode down-regulation may indicate brain vulnerability to degeneration rather than being specific to neurodegenerative processes, and that temporo-parietal junction disconnection may aid clinical detection of abnormal ageing.

Abstract

Abstract: Group comparison studies have established that activity in the posterior part of the default-mode network (DMN) is down-regulated by both normal ageing and Alzheimer’s disease (AD). In this study linear regression models were used to disentangle distinctive DMN activity patterns that are more profoundly associated with either normal ageing or a structural marker of neurodegeneration. 312 datasets inclusive of healthy adults and patients were analysed. Days of life at scan (DOL) and hippocampal volume were used as predictors. Group comparisons confirmed a significant association between functional connectivity in the posterior cingulate/retrosplenial cortex and precuneus and both ageing and AD. Fully-corrected regression models revealed that DOL significantly predicted DMN strength in these regions. No such effect, however, was predicted by hippocampal volume. A significant positive association was found between hippocampal volumes and DMN connectivity in the right temporo-parietal junction (TPJ). These results indicate that postero-medial DMN down-regulation may not be specific to neurodegenerative processes but may be more an indication of brain vulnerability to degeneration. The DMN-TPJ disconnection is instead linked to the volumetric properties of the hippocampus, may reflect early-stage regional accumulation of pathology and might be of aid in the clinical detection of abnormal ageing.

Comparable studies

Other observational and cohort studies on default mode network, most cited first.

Study Year Design Participants
A default mode of brain function Normal adult human brain 2001 Observational study
Resting-State Functional Connectivity Reflects Structural Connectivity in the Default Mode Network Healthy subjects 2008 Observational cohort
Meditation experience is associated with increased cortical thickness Participants with extensive Insight meditation experience and matched controls 2005 Observational cohort n = 20
Meditation experience is associated with differences in default mode network activity and connectivity Experienced meditators and matched meditation-naive controls 2011 Observational cohort
The precuneus/posterior cingulate cortex plays a pivotal role in the default mode network: Evidence from a partial correlation network analysis Healthy subjects 2008 Observational study

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