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REM sleep EEG slowing signals basal forebrain integrity in older adults with subjective and mild cognitive impairment
Lam A, Espinosa N, Matar E, Cross N, Fripp J, Xia Y, André C, Coulson E et al.. medRxiv, 2026-10-02
Topic: Brain imaging, connectivity and assessment
The basal forebrain is an early site of pathology in Alzheimer’s disease (AD). Within this region, the nucleus basalis of Meynert (NbM) provides the primary cholinergic input to the neocortex and supports cortical activation during rapid eye movement (REM) sleep. REM electroencephalography (EEG) slowing is observed in older adults with AD and amnestic mild cognitive impairment (MCI). This study examined the relationship between REM EEG slowing and NbM volume, and whether it differed by cognitive status, sex or sleep apnea severity. Participants aged ≥60 years with subjective cognitive impairment or MCI underwent neuropsychological and medical assessments, polysomnography and magnetic resonance imaging (MRI). REM EEG slowing was quantified as the ratio of delta and theta (<8Hz) to alpha, sigma and beta (8-32Hz) power. Bilateral NbM and Ch1-3 volume were derived from T1-weighted MRI images. Multiple linear regression and moderation analyses examined associations between REM EEG slowing and NbM volume, adjusting for age, sex, and sleep apnoea severity. To assess anatomical specificity, primary analyses were repeated using Ch1– 3 volume and non-REM EEG slowing. Exploratory analyses examined associations between NbM volume, sleep macroarchitecture, and memory. The sample comprised 116 participants (59.5% female; mean age = 70.5 years, 64.7% MCI). Greater REM EEG slowing was associated with smaller NbM volume (all p < 0.05), whereas no significant associations were observed with Ch1–3 volume and non-REM EEG slowing (all p > 0.05). Although moderation effects were not significant after FDR correction, within-group analyses suggested a stronger relationship in MCI. Smaller NbM volume was associated with longer sleep latency and poorer episodic memory (all p < 0.05). REM EEG slowing may reflect early NbM degeneration and provide a non-invasive biomarker of basal forebrain integrity in older adults with cognitive concerns, with findings showing anatomical specificity to the NbM and sleep-stage specificity to REM sleep. Longitudinal studies are required to establish its prognostic value.
Key findings
- Greater REM EEG slowing was associated with smaller NbM volume (all p < 0.05), whereas no significant associations were observed with Ch1–3 volume and non-REM EEG slowing (all p > 0.05).
- Although moderation effects were not significant after FDR correction, within-group analyses suggested a stronger relationship in MCI.
- Smaller NbM volume was associated with longer sleep latency and poorer episodic memory (all p < 0.05).
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Study details
- Study designlongitudinal study
- Participants116
- Effect size59.5%; 64.7%
- Evidence strengthModerate
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 47 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for randomised / blinded because the record does not state it. We have no data on 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 29 of the 62 points we could judge it on, which is 47 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 2 / 10 | Tier 4 — not a peer-reviewed journal (medRxiv) |
| Journal's citation record | 0 / 4 | Not a journal article, so the journal's record does not count |
| Study design | 7 / 12 | A longitudinal study following the same people over time |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 4 / 10 | Preprint — not yet peer-reviewed. Hosted on a preprint server. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 2 / 4 | 116 participants |
| Effect reported | 2 / 3 | Effect reported as a number, without an interval or test |
| 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 | — / 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 | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 29 / 62 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 29 of the 62 points we could judge it on is 47 out of 100. |
| Total | 47 / 100 | Capped to 16 because this is not a peer-reviewed article. |
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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's author list ends in “et al.”, so not every author is named. Check the citation against the original before you use it.
APA 7th
Lam, A., Espinosa, N., Matar, E., Cross, N., Fripp, J., Xia, Y., et al. (2026). REM sleep EEG slowing signals basal forebrain integrity in older adults with subjective and mild cognitive impairment. medRxiv. https://doi.org/10.64898/2026.09.30.26363850
Vancouver
Lam A, Espinosa N, Matar E, Cross N, Fripp J, Xia Y, et al. REM sleep EEG slowing signals basal forebrain integrity in older adults with subjective and mild cognitive impairment. medRxiv. 2026. doi:10.64898/2026.09.30.26363850.
BibTeX
@article{lam2026-1a861e96,
author = {Lam, A. and Espinosa, N. and Matar, E. and Cross, N. and Fripp, J. and Xia, Y. and André, C. and Coulson, E. and others},
title = {{REM sleep EEG slowing signals basal forebrain integrity in older adults with subjective and mild cognitive impairment}},
journal = {medRxiv},
year = {2026},
doi = {10.64898/2026.09.30.26363850},
url = {https://doi.org/10.64898/2026.09.30.26363850}
}
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