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Specification dependence of EEG theta/alpha ratio associations with cognitive impairment: a multiverse analysis
Chang J, Song SH.. bioRxiv, 2026-09-08
Topic: Brain imaging, connectivity and assessment
Abstract/Summary Objective The theta/alpha ratio, an index of electroencephalographic slowing, has been proposed as a marker of cognitive impairment, but estimates may depend on preprocessing, spectral, spatial, and statistical decisions. We used multiverse analysis to evaluate its robustness across plausible pipelines. Methods Two resting-state EEG datasets were analyzed. Dataset 1 included 49 controls and 100 participants with Parkinson’s disease spanning normal cognition to dementia. Dataset 2 included 29 controls, 36 patients with Alzheimer’s disease, and 23 with frontotemporal dementia. Eight decisions were varied: filtering, artifact correction, independent component analysis (ICA), referencing, spatial summary, alpha-band definition, spectral method, and covariate adjustment, yielding 1,280 specifications (universes). Results Findings: varied across the unrestricted multiverse. In Dataset 1, all universes in the exploratory family combining ICA with absolute fast Fourier transform (FFT) or Welch power yielded p < 0.05 for comparisons of controls and cognitively normal Parkinson’s disease with Parkinson’s disease dementia and produced significant associations with Montreal Cognitive Assessment scores in more than 95% of universes. In Dataset 2, absolute FFT or Welch power supported control versus Alzheimer’s disease differences in more than 95% of universes, while ICA with absolute power yielded significant Mini-Mental State Examination associations in all specifications. Higher theta/alpha ratios were consistently associated with greater cognitive impairment. Conclusions The theta/alpha ratio is a promising but specification-dependent marker of cognitive impairment, contingent particularly on ICA and spectral power quantification. Significance Identifying the analytic conditions under which theta/alpha findings remain stable supports standardized, reproducible evaluation of quantitative EEG markers of cognitive impairment. Highlights Theta/alpha ratio findings varied substantially across 1,280 plausible EEG analysis pipelines. Independent component analysis with absolute spectral power yielded the most stable effects. Higher theta/alpha ratios consistently indicated greater cognitive impairment in robust pipelines.
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APA 7th
Chang, J., & Song, S. H. (2026). Specification dependence of EEG theta/alpha ratio associations with cognitive impairment: a multiverse analysis. bioRxiv. https://doi.org/10.64898/2026.09.03.749187
Vancouver
Chang J, Song SH. Specification dependence of EEG theta/alpha ratio associations with cognitive impairment: a multiverse analysis. bioRxiv. 2026. doi:10.64898/2026.09.03.749187.
BibTeX
@article{chang2026-9e6c52cd,
author = {Chang, J. and Song, S. H.},
title = {{Specification dependence of EEG theta/alpha ratio associations with cognitive impairment: a multiverse analysis}},
journal = {bioRxiv},
year = {2026},
doi = {10.64898/2026.09.03.749187},
url = {https://doi.org/10.64898/2026.09.03.749187}
}
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Key findings
- Results Findings: varied across the unrestricted multiverse.
- In Dataset 1, all universes in the exploratory family combining ICA with absolute fast Fourier transform (FFT) or Welch power yielded p < 0.05 for comparisons of controls and cognitively normal Parkinson’s disease with Parkinson’s disease dementia and produced significant associations with Montreal Cognitive Assessment scores in more than 95% of universes.
- In Dataset 2, absolute FFT or Welch power supported control versus Alzheimer’s disease differences in more than 95% of universes, while ICA with absolute power yielded significant Mini-Mental State Examination associations in all specifications.
- Higher theta/alpha ratios were consistently associated with greater cognitive impairment.
Study details
- Participants49
- Evidence strengthLow
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 27 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for study design, effect reported and 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 17 of the 62 points we could judge it on, which is 27 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 2 / 10 | Tier 4 — not a peer-reviewed journal (bioRxiv) |
| Journal's citation record | 0 / 4 | Not a journal article, so the journal's record does not count |
| 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 | 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 | 1 / 4 | 49 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 | — / 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 | 17 / 62 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 17 of the 62 points we could judge it on is 27 out of 100. |
| Total | 27 / 100 | Capped to 16 because this is not a peer-reviewed article. |
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