Evidence map›Paper›PMID 41978992›Full record

ArticleAlzheimer's & dementia : the journal of the Alzheimer's Association2026

Olfactory decline tracks central-to-peripheral spread of tau pathology in Alzheimer's disease.

Kamar Bouchoucha, Lisa Collin, Céline Coquette, Lise Colmant, Emilien Boyer, Lara Huyghe, Lisa Quenon, Thomas Gerard, Yasmine Salman, Valérie Hox and 4 more

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Alzheimer's & dementia : the journal of the Alzheimer's Association, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

14 authors.

Kamar BouchouchaGenetic and Epigenetic Alterations of Genomes unit (GEPI), de Duve Institute, UCLouvain, Brussels, Belgium.
Lisa CollinGenetic and Epigenetic Alterations of Genomes unit (GEPI), de Duve Institute, UCLouvain, Brussels, Belgium.
Céline CoquetteGenetic and Epigenetic Alterations of Genomes unit (GEPI), de Duve Institute, UCLouvain, Brussels, Belgium.
Lise ColmantNeurology Department, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Emilien BoyerNeurology Department, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Lara HuygheLouvain Aging Brain Lab, Clinical Neurosciences division (NEUR), Institute of Neuroscience (IoNS), UCLouvain, Brussels, Belgium.
Lisa QuenonNeurology Department, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Thomas GerardLouvain Aging Brain Lab, Clinical Neurosciences division (NEUR), Institute of Neuroscience (IoNS), UCLouvain, Brussels, Belgium.
Yasmine SalmanLouvain Aging Brain Lab, Clinical Neurosciences division (NEUR), Institute of Neuroscience (IoNS), UCLouvain, Brussels, Belgium.
Valérie HoxDepartment of Otorhinolaryngology, Head and Neck Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Pascal Kienlen-CampardAging and Dementia group, Cellular and Molecular division (CEMO), Institute of Neuroscience (IoNS), UCLouvain, Brussels, Belgium.
Bernard HanseeuwNeurology Department, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Anabelle DecottigniesGenetic and Epigenetic Alterations of Genomes unit (GEPI), de Duve Institute, UCLouvain, Brussels, Belgium.ORCID 0000-0001-7893-2527
Caroline HuartDepartment of Otorhinolaryngology, Head and Neck Surgery, Cliniques Universitaires Saint-Luc, Brussels, Belgium.

Funding

Fondation LouvainFonds De La Recherche Scientifique - FNRS CCL40010417FRFS-WelbioStopAlzheimer FoundationTélévie-FNRSUCLouvain
6 · The paper itself

Abstract

introductionOlfactory decline often precedes cognitive symptoms in Alzheimer's disease (AD) and is linked to tau pathology. Yet, whether tau aggregates start in peripheral olfactory structures or spread from central regions remains debated.

methodsWe analyzed 34 post mortem human olfactory bulb (OB) and 2 neuroepithelium (ONE) samples across Braak stages, combined with ex vivo nasal swabs and standardized olfactory testing in 88 clinically characterized participants.

resultsTau aggregates appeared in the anterior olfactory nucleus layer of the OB from Braak stage III, spreading to peripheral layers only in late stages. Olfactory identification declined in the preclinical phase and was linked to central tau pathology. Discrimination worsened during the prodromal stage, while threshold impairment appeared only in dementia, reflecting the anatomical progression of tau pathology. DISCUSSION: This anatomical-functional link supports a central-to-peripheral spread of tau pathology in the olfactory system, with stage-specific deficits suggesting targeted smell tests as early AD biomarkers.

Indexed as

Alzheimer DiseaseOlfaction DisordersOlfactory Bulbtau ProteinsAgedAged, 80 and overFemaleHumansMaleMAPT protein, humantau ProteinsAlzheimer's diseasenasal brushingolfactionolfactory bulbolfactory neuroepitheliumtau pathology

Identifiers

PMID41978992
PMCPMC13077449

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LicenceCC BY-NC-ND
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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.