Preserved cholinergic forebrain integrity reduces structural connectome vulnerability in mild cognitive impairment

Area of Science:

• Neuroscience
• Neurology
• Systems Biology

Background:

• Neurodegeneration causes brain network reorganization, potentially increasing vulnerability to damage.
• The cholinergic system, specifically the cortical acetylcholine, aids adaptation in memory circuits but its broader network effects are unclear.

Purpose of the Study:

• To investigate the role of the cholinergic basal forebrain (CBFB) in mitigating the impact of strategic lesions on whole-brain networks.
• To determine if CBFB volume influences network efficiency and resilience to simulated damage in mild cognitive impairment (MCI).

Main Methods:

• Magnetic resonance imaging (MRI) was used to study 20 MCI patients and 20 controls.
• Whole-brain tractograms were analyzed as network graphs, with simulated node lesions to assess global efficiency changes.
• Relationships between CBFB volumes, network efficiency, and lesion impact were evaluated.

Main Results:

• In MCI patients, larger CBFB volumes were linked to more efficient network topology.
• Increased CBFB volumes correlated with a reduced impact of simulated lesions in the hippocampus, thalamus, and entorhinal cortex in MCI.
• These associations were not observed in elderly controls.

Conclusions:

• The cholinergic system, via the CBFB, appears to shape brain connectome configuration.
• CBFB may offer a protective effect against the global consequences of localized structural damage in MCI.
• This suggests a mechanism by which the cholinergic system enhances brain resilience in neurodegenerative conditions.