SynthesisInternational forum of allergy & rhinology2025
Olfactory Impairment and Incident Cognitive Decline: A Systematic Review and Meta-Analysis.
Synthesis in International forum of allergy & rhinology, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers, 1 of them a synthesis that pooled 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.
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.
Who cites it
3 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Olfactory Impairment and Incident Cognitive Decline: A Systematic Review and Meta-Analysis.International forum of allergy & rhinology · 2025Pooled it
- Olfactory decline in aging: longitudinal trajectories and associations with cognitive decline and postmortem neuropathology.medRxiv : the preprint server for health sciences · 2026Article
- Plasma lipids connecting olfaction with cognition and physical function.Scientific reports · 2026Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
18 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundOlfactory impairment (OI) is associated with poor ageing outcomes. While cross-sectional studies found a high prevalence of OI among patients with neurodegenerative diseases, the temporal relationship remains unclear. This meta-analysis aims to synthesise the longitudinal association of OI with cognitive decline (CD).
methodsPubMed, Embase and Web of Science were searched through August 9, 2024 for longitudinal studies reporting on self-reported and objectively measured OI in adults, in association with CD, measured using validated methods. The outcome of interest was incident CD. Independent authors extracted data, assessed for bias and graded the strength of evidence. A mixed-effects meta-analysis with subgroup, sensitivity and bias analyses was conducted. The population-attributable fraction (PAF) of OI-associated CD was calculated.
resultsThis study included 48 articles and 37,783 participants. OI patients had a 2.06-fold greater risk of any CD (risk ratio [RR] = 2.06; 95% CI = 1.87‒2.26, I
conclusionOI may increase the risk of CD, with poorer olfaction linked to greater risks. OI should be assessed as a potential cognitive screening tool, and cognitive screening should be considered in patients with long-standing OI.
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Registered trials
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 Socratic graph.