Talk:Dementia with Lewy bodies

Blood tests

The lead says: "A presumptive diagnosis can be made if several disease features are present, such as symptoms or certain results of blood tests, neuropsychological tests, imaging, and sleep studies."

But from the text it looks like blood tests are mainly used:

• To rule out other conditions: "laboratory testing to rule out conditions that may cause symptoms similar to dementia, such as abnormal thyroid function, syphilis, HIV, and vitamin deficiencies."
• In research: "Other tests to detect alpha-synuclein with blood tests are under study as of 2021."

Did I miss something? A455bcd9 (talk) 09:30, 12 December 2022 (UTC)

I have restored older wording, which morphed over time, confusingly as you pointed out! Thx, A455bcd9. SandyGeorgia (Talk) 14:28, 12 December 2022 (UTC)

Thanks!

I also wonder:

1. "Since 2001, 123iodine-metaiodobenzylguanidine (123I-MIBG) myocardial scintigraphy has been used diagnostically in East Asia (principally Japan),[40][135][136] but not in the US." => what about the rest of the world? And which countries in East Asia besides Japan? (China? South Korea? Taiwan?)
2. "Commercial skin biopsy tests for DLB are available in the US": since when? how much do they cost? I guess these tests were FDA approved, do we know how efficient they are? The following sentence ("the role of these tests in clinical practice has not been established") isn't clear (although the source doesn't say much more unfortunately...)
3. "the FDA has given a 'breakthrough device' authorization for CSF testing": when? (found this 2022 source but not RS)

A455bcd9 (talk) 14:39, 12 December 2022 (UTC)

Thx, A4; I have an app't this morning, so will respond later today, Bst, SandyGeorgia (Talk) 14:54, 12 December 2022 (UTC)

To use: Bousiges O, Blanc F (June 2022). "Biomarkers of dementia with Lewy bodies: differential diagnostic with Alzheimer's disease". Int J Mol Sci. 23 (12). doi:10.3390/ijms23126371. PMC 9223587. PMID 35742814.{{cite journal}}: CS1 maint: unflagged free DOI (link) SandyGeorgia (Talk) 15:22, 12 December 2022 (UTC)

1. Scintigraphy

From sources

Tousi (2017): Reduced uptake on metaiodobenzylguanidine myocardial scintigraphy correlates with reduced postganglionic sympathetic cardiac innervation in Lewy body diseases, which can increase specificity for discriminating probable DLB from probable AD in milder cases of dementia. However, the latter is more commonly used in Japan and is not used in the USA. The evidence supporting the benefit of other therapeutic modalities is limited in DLB due to lack of extensive studies. Although there is no direct biomarker of DLB, there are three indicative biomarkers: reduced dopamine transporter uptake in the basal ganglia as demonstrated by SPECT or PET, polysomnographic confirmation of REM sleep without atonia, and low uptake iodine-MIBG myocardial scintigraphy which has gained more recognition in Japan and East Asia [6] but is not used clinically in the USA. 6. Manabe Y, Inui Y, Toyama H, Kosaka K. 123I-Metaiodobenzylguanidine myocardial scintigraphy with Curr Treat Options Neurol (2017) 19:42 Page 17 of 19 42 early images alone is useful for the differential diagnosis of dementia with Lewy bodies. Psychiatry Res. 2017;261:75–9. PMID 28152401 Kosaka 2017, Yamada M, Chapter 12, p. 162. Article in a very large book: sources the 2001, nothing about which countries. Bousiges O, Blanc F (June 2022) MIBG myocardial scintigraphy is an imaging technique for estimating sympathetic nerve damage, which post-mortem studies show as reduced in DLB. These damages are seen in primary heart disease, diabetic neuropathy, and also PD and DLB [42]. For DLB at the stage of dementia, the sensitivity ranges from 68.9% [53] N = 61 DLB (ratio method) to 100% N = 19 DLB (ratio method) [42]. The specificity of MIBG scintigraphy when compared to healthy controls or AD is usually excellent: 87% [53], to 92% [42] N = 19 DLB, ratio method [42,53]. Although MIBG scintigraphy seems to be informative, there is a lack of phase 3 studies to validate this biomarker in its use as a differential diagnostic tool between DLB and AD [54].

The reference to East Asia comes from Tousi (2017), but after scouring new and old sources, I can find no further information specifying which countries. Bousiges & Blanc explain why it's not used elsewhere, so that might be useful info to include. Personal opinion: I suspect it just hasn't taken hold in the rest of the world because it's mostly useful as possible discriminator between DLB and AD (an area still not well defined vis-a-vis biomarkers), and there are other ways of doing that-- that is, a lack of interest or funding in re-inventing the wheel with a new methodology in the Western world. SandyGeorgia (Talk) 18:34, 12 December 2022 (UTC)

2. Commercial biomarker tests

From sources

Armstrong (2017): In the United States, CSF testing for evidence of a synucleinopathy is available through a Food and Drug Administration 'breakthrough device designation', but this test is not currently covered by insurance providers and its role in routine clinical diagnosis is not yet established. ... commercial testing for synucleinopathies using skin punch biopsies is now available in the United States. As with CSF α-synuclein testing, the role that skin biopsy plays in routine clinical diagnosis of DLB is yet to be established. Han (2022) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9148991/ gives an update on the limitations (nothing new). Similar at PMID 35670835 Santos (2022) PMID 36423207 However, CSF analysis procedures and advanced imaging modalities are either invasive or high-priced, and routinely unavailable. Blanc, Bousiges (2022), PMID 35491246: CSF Alpha-synuclein assay in the CSF has also an interest in the discrimination between DLB and AD but not in segregation between DLB and healthy elderly subjects. CSF synuclein RT-QuIC seems to be an excellent biomarker but its application in clinical routine remains to be demonstrated, given the non-automation of the process.

Similarly, I've re-examined the sources and done a new search, and have come up with little new information except that they aren't currently approved by insurance. Multiple potential biomarkers are under study by different groups, and all of them require very expensive research with the jury still out on all. (FDA approval has somewhat lost relevance following on recent scandals of product approval of dubious validity prompted by patient advocates (Aducanumab), resulting in the resignation of leading researchers from the FDA advisory panel which unanimously rejected the product.)

We can talk about what to add to improve clarity based on the new sources above, but we don't have a lot to work with. SandyGeorgia (Talk) 19:03, 12 December 2022 (UTC)

3. FDA 'breakthrough device' authorization I don't know when or what device was approved (or how many consumers are falling for those tests), but I suspect the approval you found was a different one than the one mentioned in the cited review. SandyGeorgia (Talk) 19:05, 12 December 2022 (UTC)

On the big picture, I hope the article is not leaving the impression that distinction between AD and DLB has reached a state where biomarkers can be easily or commercially applied: we aren't there yet, and most are still research protocols, expensive, and require considerable judgment. Unsure how to make sure the article is not leaving faulty impressions on this, but regardless of cost or FDA approval, you can't just get a test to help distinguish whether dementia is AD or DLB (which is what all of them are aiming to do). That pathologies frequently co-exist (DLB and AD) is a confounding factor in the whole matter of biomarkers. SandyGeorgia (Talk) 20:15, 12 December 2022 (UTC)

Thanks for taking the time to conduct this thorough research. It's quite interesting. And unfortunate. Although we cannot say more than RS do. I only added "however" to insist a bit more and avoid leaving readers with faulty impressions. Feel free to revert if you think it's not relevant. a455bcd9 (Antoine) (talk) 21:21, 12 December 2022 (UTC)

I did a bit more to work in the three new sources,[1] without howevering; pls let me know if this is more clear ? SandyGeorgia (Talk) 22:42, 12 December 2022 (UTC)

Perfect: thanks! a455bcd9 (Antoine) (talk) 09:16, 13 December 2022 (UTC)