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Melatonin levels in the Alzheimer's disease continuum: a systematic review
Nous A, Engelborghs S, Smolders I.. Alzheimer's research & therapy, 2021-02-23
Topic: Plasma and spinal-fluid biomarkers
Background The search for new Alzheimer's disease (AD) cerebrospinal fluid (CSF) and blood biomarkers with potential pathophysiological and clinical relevance continues, as new biomarkers might lead to improved early and differential diagnosis, monitoring of disease progression and might even identify new druggable targets. Melatonin might be an interesting biomarker as an inverse correlation between CSF melatonin levels, and severity of the neuropathology as measured by Braak stages has been described. Melatonin can be measured in different body fluids, such as CSF, blood, saliva and urine. Objectives The aim of this systematic review was to review all available studies regarding melatonin levels in different body fluids in the AD continuum and give an extensive overview of reported outcomes. Methods We included papers comparing melatonin levels between healthy controls and human patients belonging to the AD continuum. A systematic search of PubMed and Web of Science led to inclusion of 20 full-length English papers following exclusion of duplicates. Results This systematic literature search showed that disruptions in melatonin levels occur with age, but also in AD when compared to age-matched controls. Night-time melatonin levels were found to be lower in CSF and blood of AD patients as compared to controls. Literature was not conclusive regarding alterations in blood daytime melatonin levels or regarding saliva melatonin in AD patients. Decreased total and night-time melatonin production has been described in urine of AD patients. Conclusion Our systematic review shows evidence for disruptions in (night-time) melatonin levels in AD as compared to age-matched controls. Although more studies are needed to understand the contribution of disruption of the melatonergic system to the pathophysiology of AD, the potential anti-AD effects that have been attributed to melatonin, renders research on this topic relevant for the discovery of potential future treatment effects of melatonin for AD. The use of melatonin as potential blood biomarker for disease progression should also be further investigated.
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APA 7th
Nous, A., Engelborghs, S., & Smolders, I. (2021). Melatonin levels in the Alzheimer's disease continuum: a systematic review. Alzheimer's research & therapy. https://doi.org/10.1186/s13195-021-00788-6
Vancouver
Nous A, Engelborghs S, Smolders I. Melatonin levels in the Alzheimer's disease continuum: a systematic review. Alzheimer's research & therapy. 2021. doi:10.1186/s13195-021-00788-6. PMID: 33622399.
BibTeX
@article{nous2021-33622399,
author = {Nous, A. and Engelborghs, S. and Smolders, I.},
title = {{Melatonin levels in the Alzheimer's disease continuum: a systematic review}},
journal = {Alzheimer's research \& therapy},
year = {2021},
doi = {10.1186/s13195-021-00788-6},
pmid = {33622399},
url = {https://doi.org/10.1186/s13195-021-00788-6}
}
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Key findings
- Results This systematic literature search showed that disruptions in melatonin levels occur with age, but also in AD when compared to age-matched controls.
- Night-time melatonin levels were found to be lower in CSF and blood of AD patients as compared to controls.
- Conclusion Our systematic review shows evidence for disruptions in (night-time) melatonin levels in AD as compared to age-matched controls.
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Study details
- Study designsystematic review
- Evidence strengthHigh
How this study scored 71/100
Published in a peer-reviewed journal, and it is a systematic review of all the studies on the question. Scored zero for sample size, effect reported and studied in people because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 41 of the 58 points we could judge it on, which is 71 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Alzheimer's research & therapy) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 12 / 12 | A systematic review of all the studies on the question |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 3 / 5 | 2021 — within 6 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 33622399) |
| Free to read | 2 / 2 | Free to read |
| Points | 41 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 41 of the 58 points we could judge it on is 71 out of 100. |
| Total | 71 / 100 | — |
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