Specification dependence of EEG theta/alpha ratio associations with cognitive impairment: a multiverse analysis
Year: 2026
Type: preprint
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.
Authors: Jinwon Chang, Seo Ho Song
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7211995995