Cerebrovascular disease is common in patients on the Lewy body (LB) continuum (dementia with Lewy bodies (DLB) and prodromal-DLB). White matter signal abnormality (WMSA) volume is higher in patients with LB than controls, both globally and in cholinergic white matter. However, it remains unknown if the higher WMSA in cholinergic white matter reflects selective cholinergic vulnerability or results from higher global WMSA. We modelled cingulate and external capsule cholinergic white matter pathways using MRI and segmented WMSA overlapping cholinergic pathways and per brain lobe. We found that patients on the LB-continuum (n = 33) had higher volume and proportion of WMSA in the cholinergic white matter compared to controls (n = 36), independent of global WMSA. Cholinergic WMSA was associated with neurodegeneration in the basal forebrain, decreased integrity of cingulate and external capsule pathways and attention and memory performance. These findings may suggest a selective vulnerability of cholinergic pathways in patients with LB.

• Publication type
• Journal Article MeSH

Dementia with Lewy bodies often presents with cholinergic degeneration and varying degrees of cerebrovascular disease. There is a lack of radiological methods for evaluating cholinergic degeneration in dementia with Lewy bodies. We investigated the potential of the Cholinergic Pathway Hyperintensities Scale (CHIPS) in identifying cerebrovascular disease-related disruptions in cholinergic white matter pathways, offering a practical and accessible method for assessing cholinergic integrity in neurodegenerative diseases. We assessed the associations of CHIPS with regional brain atrophy, Alzheimer's disease co-pathology and clinical phenotype. Additionally, we compared its diagnostic performance to that of other manual and automated evaluation methods. We included 82 individuals (41 patients in the Lewy body continuum with either probable dementia with Lewy bodies or mild cognitive impairment with Lewy bodies, and 41 healthy controls) from the Sant Pau Initiative on Neurodegeneration cohort. We used CHIPS to assess cholinergic white matter signal abnormalities (WMSA) on MRI, while tractography mean diffusivity provided a complementary measure of cholinergic WMSA. For global WMSA evaluation, we used the Fazekas scale and FreeSurfer. CHIPS successfully identified cerebrovascular disease-related disruptions in cholinergic white matter pathways, as evidenced by its association with tractography and global WMSA markers (P < 0.005 for all associations). Lewy body patients showed a significantly higher degree of WMSA in the external capsule cholinergic pathway despite no significant differences in global WMSA compared to controls. CHIPS score in the posterior external capsule and the mean diffusivity in the external capsule and cingulum exceeded the threshold for an optimal biomarker (sensitivity and specificity values above 80%) in discriminating Lewy body patients from controls. Furthermore, higher CHIPS scores, Fazekas scale and tractography mean diffusivity were associated with more pronounced frontal atrophy in Lewy body patients but not in controls. No associations were found for the four WMSA and integrity methods with the core clinical features, clinical or cognitive measures, or CSF biomarkers. In conclusion, cholinergic WMSA were more pronounced in Lewy body patients compared to healthy controls, independently of global WMSA. Our findings indicate that cerebrovascular disease-related disruptions in cholinergic white matter may be linked to frontal atrophy in Lewy body patients. Clinically, we demonstrate the potential of CHIPS to assess cholinergic WMSA using widely available MRI sequences. Our data suggest cerebrovascular disease co-pathology could drive the cholinergic degeneration in Lewy body patients, opening opportunities for therapeutic interventions targeting vascular health from mild cognitive impairment with Lewy bodies through manifest dementia with Lewy bodies.

• Keywords
• CHIPS, cholinergic white matter pathways, dementia with Lewy bodies, white matter signal abnormalities,
• Publication type
• Journal Article MeSH

Previous studies have shown that the cholinergic nucleus basalis of Meynert and its white matter projections are affected in Alzheimer's disease dementia and mild cognitive impairment. However, it is still unknown whether these alterations can be found in individuals with subjective cognitive decline, and whether they are more pronounced than changes found in conventional brain volumetric measurements. To address these questions, we investigated microstructural alterations of two major cholinergic pathways in individuals along the Alzheimer's disease continuum using an in vivo model of the human cholinergic system based on neuroimaging. We included 402 participants (52 Alzheimer's disease, 66 mild cognitive impairment, 172 subjective cognitive decline and 112 healthy controls) from the Deutsches Zentrum für Neurodegenerative Erkrankungen Longitudinal Cognitive Impairment and Dementia Study. We modelled the cholinergic white matter pathways with an enhanced diffusion neuroimaging pipeline that included probabilistic fibre-tracking methods and prior anatomical knowledge. The integrity of the cholinergic white matter pathways was compared between stages of the Alzheimer's disease continuum, in the whole cohort and in a CSF amyloid-beta stratified subsample. The discriminative power of the integrity of the pathways was compared to the conventional volumetric measures of hippocampus and nucleus basalis of Meynert, using a receiver operating characteristics analysis. A multivariate model was used to investigate the role of these pathways in relation to cognitive performance. We found that the integrity of the cholinergic white matter pathways was significantly reduced in all stages of the Alzheimer's disease continuum, including individuals with subjective cognitive decline. The differences involved posterior cholinergic white matter in the subjective cognitive decline stage and extended to anterior frontal white matter in mild cognitive impairment and Alzheimer's disease dementia stages. Both cholinergic pathways and conventional volumetric measures showed higher predictive power in the more advanced stages of the disease, i.e. mild cognitive impairment and Alzheimer's disease dementia. In contrast, the integrity of cholinergic pathways was more informative in distinguishing subjective cognitive decline from healthy controls, as compared with the volumetric measures. The multivariate model revealed a moderate contribution of the cholinergic white matter pathways but not of volumetric measures towards memory tests in the subjective cognitive decline and mild cognitive impairment stages. In conclusion, we demonstrated that cholinergic white matter pathways are altered already in subjective cognitive decline individuals, preceding the more widespread alterations found in mild cognitive impairment and Alzheimer's disease. The integrity of the cholinergic pathways identified the early stages of Alzheimer's disease better than conventional volumetric measures such as hippocampal volume or volume of cholinergic nucleus basalis of Meynert.

• Keywords
• Alzheimer’s disease, CSF markers, MRI, cholinergic system, nucleus basalis of Meynert,
• MeSH
• Alzheimer Disease * psychology   MeSH
• White Matter * MeSH
• Cholinergic Agents MeSH
• Cognitive Dysfunction * psychology   MeSH
• Humans MeSH
• Brain MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cholinergic Agents MeSH