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Quantitative susceptibility mapping reveals differences between subtypes of Lewy body dementia
Rohan Bhome, George E. C. Thomas, Naomi Hannaway, Ivelina Dobreva, Angeliki Zarkali, Karin Shmueli, James Howard Cole, Rimona Sharon Weil. Brain, 2025-09-03
Topic: Brain proteins, microglia and lab models
Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are subtypes of Lewy body dementia, and are considered two ends of a disease spectrum. However, conventional MRI neuroimaging, mainly focused on grey matter volume and thickness, has failed to establish whether underlying processes differ between them. Understanding these differences could enable targeted and subtype-specific treatments to be developed. We applied quantitative susceptibility mapping (QSM), an advanced neuroimaging technique sensitive to tissue iron, to examine differences in tissue composition between these Lewy body dementia subtypes. We performed both voxel-wise and region of interest analyses to compare QSM values in 66 people with Lewy body dementia (45 DLB; 21 PDD), 86 people with Parkinson's disease with normal cognition (PD-NC) and 37 healthy controls. We also assessed relationships between QSM values and measures of both cognitive performance and overall disease severity in people with Lewy body dementia. We found that people with Lewy body dementia had higher QSM values in widespread brain regions, compared with cognitively normal people with PD, and that people with PDD had higher QSM values across many brain regions, compared with people with DLB. Further, we showed a positive relationship between QSM values and overall disease severity, measured using the Movement Disorder Society Unified Parkinson's Disease Rating Scale in people with Lewy body dementia, in the right thalamus, left pallidum, bilateral substantia nigra, bilateral middle frontal, temporal and lateral occipital lobes, right precentral and superior frontal cortices. In a region of interest analysis, we showed that people with PDD had higher QSM values than cognitively normal people with PD and controls in the substantia nigra pars reticulata. Our findings indicate neurobiological differences between subtypes of Lewy body dementia, that can be detected by exploiting QSM's sensitivity to tissue composition. Based on this, DLB and PDD could be considered as distinct conditions in the clinic and in clinical trials, and may respond to different treatments. Our finding that QSM values relate to real-world measures of overall disease severity in Lewy body dementia indicates its potential as an imaging biomarker for clinical trials of Lewy body dementia interventions.
Key findings
- We also assessed relationships between QSM values and measures of both cognitive performance and overall disease severity in people with Lewy body dementia.
- We found that people with Lewy body dementia had higher QSM values in widespread brain regions, compared with cognitively normal people with PD, and that people with PDD had higher QSM values across many brain regions, compared with people with DLB.
- Further, we showed a positive relationship between QSM values and overall disease severity, measured using the Movement Disorder Society Unified Parkinson's Disease Rating Scale in people with Lewy body dementia, in the right thalamus, left pallidum, bilateral substantia nigra, bilateral middle frontal, temporal and lateral occipital lobes, right precentral and superior frontal cortices.
- In a region of interest analysis, we showed that people with PDD had higher QSM values than cognitively normal people with PD and controls in the substantia nigra pars reticulata.
- Our findings indicate neurobiological differences between subtypes of Lewy body dementia, that can be detected by exploiting QSM's sensitivity to tissue composition.
Why it matters
Using quantitative susceptibility mapping, this study found higher values in widespread brain regions in people with Lewy body dementia compared with cognitively normal people with Parkinson's disease, and higher values in Parkinson's disease dementia than in dementia with Lewy bodies. The authors suggest understanding these differences could enable targeted subtype-specific treatments, but no treatment, cure or prevention is tested.
Study details
- Participants66
- Evidence strengthLow
How this study scored 48/100
Published in a leading specialty journal. Scored zero for study design, effect reported and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Brain) |
| Journal's citation record | 4 / 4 | Brain: journal h-index 503 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 4 / 5 | 2025 — within 3 year(s) of the newest study here |
| Sample size | 1 / 4 | 66 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 2 / 7 | Cited 7 times (OpenAlex, 2026-10-10) |
| Citations per year | 1 / 5 | 2.3 citations a year over 3 year(s) since 2025 |
| Impact for its field and year | 3 / 6 | Cited 3.9× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 0 / 6 | No other study in this library cites it |
| Still being cited | 1 / 4 | Cited 7 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author Rimona Sharon Weil: h-index 39 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | University College London: institution h-index 2,029 (OpenAlex) |
| Multi-centre collaboration | 1 / 3 | OpenAlex lists 3 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 40904193) |
| Free to read | 2 / 2 | Free to read |
| Total | 48 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. The record names 8 authors; APA and Vancouver show the first six, BibTeX and the downloads carry all of them. Check the citation against the original before you use it.
APA 7th
Bhome, R., Thomas, G. E. C., Hannaway, N., Dobreva, I., Zarkali, A., Shmueli, K., et al. (2025). Quantitative susceptibility mapping reveals differences between subtypes of Lewy body dementia. Brain. https://doi.org/10.1093/brain/awaf325
Vancouver
Bhome R, Thomas GEC, Hannaway N, Dobreva I, Zarkali A, Shmueli K, et al. Quantitative susceptibility mapping reveals differences between subtypes of Lewy body dementia. Brain. 2025. doi:10.1093/brain/awaf325. PMID: 40904193.
BibTeX
@article{bhome2025-40904193,
author = {Bhome, Rohan and Thomas, George E. C. and Hannaway, Naomi and Dobreva, Ivelina and Zarkali, Angeliki and Shmueli, Karin and Cole, James Howard and Weil, Rimona Sharon},
title = {{Quantitative susceptibility mapping reveals differences between subtypes of Lewy body dementia}},
journal = {Brain},
year = {2025},
doi = {10.1093/brain/awaf325},
pmid = {40904193},
url = {https://doi.org/10.1093/brain/awaf325}
}
Studies this one cites
Referenced by this study and also in the alzhub library, so you can read them here.