Sniffing Out Psychosis: Can Your Sense of Smell Predict Mental Health?
"New research explores the link between olfactory function and psychosis risk in young adults, offering a potential early detection method."
The ability to smell, often taken for granted, is emerging as a potential indicator of deeper neurological processes. For years, researchers have observed a connection between a compromised sense of smell and various mental health conditions, most notably psychosis. Now, a new study delves into this relationship, specifically examining how olfactory function relates to cognitive abilities in young adults at clinical high risk for psychosis.
Psychosis, characterized by distorted perceptions of reality, typically emerges in early adulthood. Identifying individuals at risk before the full onset of the condition is crucial for early intervention and potentially mitigating the severity of the illness. This study, conducted in China, explores whether deficits in the sense of smell could serve as an early warning sign.
Researchers at the Second Xiangya Hospital and collaborating institutions investigated olfactory and cognitive functions in a group of Chinese individuals considered at clinical high risk for psychosis (CHRs). Using a specially adapted olfactory test for East Asians, the study aimed to determine if these individuals exhibited differences in their sense of smell compared to healthy controls, and if these differences correlated with cognitive performance.
From Psychosis History to Olfactory Research
Understandings of psychosis have shifted from ancient beliefs toward modern psychiatric diagnosis and treatment. Research has reported abnormal olfactory function in schizophrenia and other psychotic disorders, and a 2025 pre-registered meta-analysis set out to update the evidence across schizophrenia-spectrum disorders and examine demographic and clinical influences. Studies of first-episode psychosis have also examined relationships between olfactory function and the brain, though the available research in psychotic disorders is described as limited. In schizophrenia, greater olfactory disturbance has been associated with more negative symptoms and self-reported anhedonia, while mood-associated psychosis patients performed comparably to controls in one study.
Smell Test as Early Indicator
The study compared 19 individuals at clinical high risk for psychosis (CHRs) with 37 healthy controls (HCs). Participants, aged 13-30, underwent olfactory testing using the Odor Stick Identification Test for Japanese (OSIT-J), adapted for use in East Asian populations. This test presents 12 familiar odors, requiring participants to identify each from a selection of options.
- CHRs scored significantly lower than HCs on the OSIT-J, indicating impaired olfactory identification.
- CHRs also performed worse on all cognitive tests, demonstrating deficits in verbal memory and executive function.
- Olfactory scores showed a moderate positive correlation with HVLT-R scores (verbal memory) and negative correlations with TMT-B and SCWT scores (executive function).
Testing Smell as an Early Signal
A study of people at clinical risk for psychosis reported lower olfactory-identification scores than healthy controls, alongside lower scores on other cognitive tests; its authors suggested smell impairment may be an early change in psychosis. A 2024 study directly compared olfactory identification in ultra-high-risk participants who later transitioned to psychosis (UHR-T) and those who remained at risk without a psychotic episode (UHR-NT). Separately, a pre-registered meta-analysis published in 2025 aimed to update the evidence on olfactory function across schizophrenia-spectrum disorders and assess demographic and clinical moderators. These research directions examine whether smell differences are associated with risk or illness, but the provided material does not establish a diagnostic prediction.
Association Is Not a Complete Explanation
Olfactory deficits in psychotic disorders have been reported across identification, familiarity, and memory measures relative to age-matched controls. Yet early-stage research has also emphasized the need to identify which specific symptoms and cognitive changes accompany olfactory dysfunction, including possible links with social cognition. One source describes olfactory dysfunction as having predictive value for prognosis and disease course, but the supplied material does not give measures of predictive accuracy or show that smell testing alone can forecast an individual's course. The evidence therefore supports studying olfactory differences while leaving their precise clinical meaning and usefulness unresolved.
A New Direction for Mental Health
This study provides compelling evidence for the potential of olfactory testing as a tool for early psychosis detection, particularly within East Asian populations. By identifying individuals at risk before the full onset of symptoms, interventions can be implemented to potentially delay or mitigate the severity of the illness.
Toward Patient-Centered Olfactory Research
A research-trends analysis highlights the value of mapping foundational resources, including key journals and authoritative authors. It also points to assessing quality of life alongside objective olfactory testing as a way to support patient-centered care. A 2023 review describes olfactory pathways as relevant to higher brain functions and discusses their involvement in mental illness, while noting that their role has been underestimated. The supplied material also identifies a study investigating whether olfactory-identification deficits at first episode relate to four-year outcomes, but provides no outcome findings.
Tracing Nasal Biology to Brain Function
A proposed research project hypothesizes that the olfactory system contributes to clinical domains of higher brain function. It aims to investigate, in animal models, how pathology in the olfactory epithelium may alter the olfactory system and thereby affect higher brain function, with later validation planned. A 2022 review similarly reports that inflammation of the olfactory epithelium may affect maturation of the olfactory system and its functional connectivity with brain regions involved in higher functions relevant to psychiatric conditions. Together, these sources describe a mechanistic research direction, not a settled explanation for psychosis.
While these findings are promising, further research is needed to validate these results and explore the underlying mechanisms connecting olfactory and cognitive functions in psychosis. Longitudinal studies, with larger and more diverse samples, are crucial to determine the precise timing of olfactory impairment and its predictive value.
Ultimately, this research highlights the importance of considering the sense of smell as a valuable indicator of mental health. Integrating olfactory assessments into routine screenings could revolutionize the early detection and intervention strategies for psychosis and other related conditions, paving the way for more proactive and personalized mental healthcare.