MRI Study Maps Brain Regions Most Vulnerable in Lewy Body Dementia
An analysis of 89 people with dementia with Lewy bodies and 89 matched controls found that cortical thinning was concentrated in brain regions associated with higher mitochondrial activity, synaptic signaling and specific neurotransmitter systems. The findings point to selective molecular and network vulnerabilities rather than uniform degeneration, although the study identifies associations rather than a treatment or proven causal mechanism.
A brain-imaging study has identified molecular and network features associated with regions that are more vulnerable to cortical thinning in dementia with Lewy bodies, a condition characterized by the spread of misfolded α-synuclein through the central nervous system. The findings suggest that degeneration is not distributed evenly across the cortex.
The analysis included 89 patients with dementia with Lewy bodies and 89 matched controls. Researchers used T1-weighted magnetic resonance imaging to create maps of cortical thickness, manually correcting the regional estimates before comparing them with gene-expression data from healthy postmortem human brains.
The team then examined which molecular pathways were associated with reduced thickness and whether the affected regions corresponded to the distribution of neurotransmitter systems or large-scale structural connections in the brain.
Cortical thinning was most prominent in areas that, in healthy brains, showed higher expression of genes involved in mitochondrial function and synaptic transmission. Mitochondria are involved in cellular energy production, while synaptic transmission allows neurons to communicate. In the context of this study, the findings indicate that regions with greater activity in these systems may be more vulnerable to the pathological processes linked to dementia with Lewy bodies.
The gene-expression profile associated with thinning overlapped significantly with pathways linked to Parkinson’s disease and Alzheimer’s disease. That overlap supports the possibility of shared biological processes across Lewy body- and Alzheimer-type neurodegeneration, but it does not establish that any one pathway caused the observed tissue loss.
The researchers also identified 90 genes associated with cortical thinning that did not overlap with Parkinson’s or Alzheimer’s disease pathways. These genes were enriched for GABAergic signaling, which involves the neurotransmitter system centered on gamma-aminobutyric acid.
Spatial analyses found that the regions with the largest reductions in cortical thickness coincided with distributions of several receptor systems, including GABAA, serotonin 5-HT1A, 5-HT1B and 5-HT4, and dopamine D2 receptors. The pattern of thinning also followed structural connectivity between brain regions, consistent with the possibility that network organization constrains how pathology spreads.
The study therefore links dementia with Lewy bodies to selective molecular and connectivity-related patterns of cortical vulnerability. Because the work used MRI measurements and gene-expression mapping, it describes associations between regional brain changes and biological features; it does not demonstrate that altering mitochondrial function, synaptic signaling, neurotransmitter systems or connectivity would prevent or reverse the disease.
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