Olfactory Function and Delayed Neurocognitive Recovery

July 28, 2025 updated by: Yuan Shen, MD, PhD, Shanghai 10th People's Hospital

Effects of Odor Enrichment on Delayed Neurocognitive Recovery

To explore whether odor enrichment can reduce the risk of delayed neurocognitive recovery as an intervention strategy.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Postoperative neurocognitive disorder, one of the most common postoperative complications in older adults, includes acute postoperative delirium, delayed neurocognitive recovery (within the 30 days recovery period, dNCR), and postoperative neurocognitive dysfunction (from expected recovery 30 days to 12 months). Previous studies showed that the incidence of dNCR ranged from 18% to 40% and is mainly characterized by cognitive impairment, which can develop into long-term cognitive impairment, even elevating the risk of Alzheimer's Disease (AD) related dementia and premature mortality. These symptoms can have significant adverse effects on quality of life and may increase the risk of other physical and psychological disorders, potentially impacting social stability. These statistics underscore the importance of early detection and timely intervention in mitigating the long-term effects of dNCR. Despite the significance of dNCR, effective treatment options remain elusive.

Based on these insights, previous studies have explored the impact of olfactory enrichment in animal models. Zhang et al. demonstrated that surgery and anesthesia could cause olfactory impairment, which might contribute to dNCR, while suggesting that odor enrichment, a non-pharmacological intervention, could reduce postoperative cognitive impairment in animal models. Olfactory enrichment, also known as olfactory training, is a safe and affordable treatment and may have preventative or supportive effects on olfactory function or cognitive function. Evidence supports its effectiveness in treating olfactory function from various causes and in reducing cognitive impairment.

Despite these findings, there is limited research on whether odor enrichment can serve as a mitigating strategy for dNCR among human populations. To address this gap, we conducted a clinical study to investigate whether odor enrichment could mitigate dNCR in geriatric patients and to explore the relationship between olfactory function and dNCR.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
131

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • China
    • Shanghai
      • Shanghai, Shanghai, China, 200072
        • Shanghai Tenth People's Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

65 years and older (Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. were aged at least 65 years old;
  2. were expected a postoperative hospital stay of at least 7 days;
  3. had American Society of Anesthesiologist (ASA) class I to II;
  4. were native Mandarin speakers;
  5. had been referred for a total knee or hip replacement under general anesthesia.

Exclusion Criteria:

  1. were prior diagnosed of neurologic diseases by the International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10);
  2. had a history of mental disorders diagnosed using the Diagnostic and Statistical Manual of Mental Disorders (DSM-5);
  3. had a history of illness or surgery with nasal or sinus;
  4. caught cold within one week;
  5. impaired vision or auditory function which may affect the assessments;
  6. were unwilling to comply with the protocol or procedures;
  7. did not pass the Mini-mental State Examination (illiterates get less than 18 points, primary school graduates get less than 20 points, secondary school graduates or higher get less than 24 points) .

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Intervention Group
Patients randomly assigned to intervention group will get odor enrichment during the perioperative period
Behavioral: Odor Enrichment
Patients in intervention group will get odor enrichment during perioperative period (3 days before the surgery and 7 days after the surgery). Odor-enriched participants were exposed daily for 24 hours to different aromatic fragrances (phenyl ethyl alcohol - rose; eucalyptol - eucalyptus; citronellal - lemon; eugenol - cloves) referred to previous studies. Odors were changed for each subject after 24 hours. According to previous studies, 10 drops of the 100% essential oil (0.5 ml) were dropped on a fabric which was placed in tea bags hanging at the hospital bedside.
No Intervention: Non-intervention Group
Patients randomly assigned to non-intervention group will not get any odor enrichment during the perioperative period

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Incidence of dNCR
Time Frame: 3 days before surgery (baseline) and 7 days after surgery (follow-up)
Participants underwent neuropsychological test battery, which referred to International Study Group of Postoperative Cognitive Dysfunction (ISPOCD) test battery and modified according to the characteristics of Chinese patients. The neuropsychological test battery consisted of the Hopkins Verbal Learning Test-Revised (HVLT-R), Brief Visuo-spatial Memory Test-Revised (BVMT-R), Trails Making Test (TMT), Digital Span Test (DST), HVLT-R Delayed Recall Test, HVLT-R Recognition Discrimination Index, BVMT-R Delayed Recall Test, BVMT-R Recognition Discrimination Index and Verbal Fluency Test (VFT). According to the International Study of Perioperative neurocognitive disorder definition, dNCR was diagnosed by calculating the "Z-score".
3 days before surgery (baseline) and 7 days after surgery (follow-up)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Olfactory identification ability
Time Frame: 3 days before surgery (baseline) and 7 days after surgery (follow-up)
Five-odor-olfactory detection arrays were applied to test the odor identification ability of the participants three days before and then about 7 days after the surgery. This test consisted of 5 pen-shaped test sticks without labels containing five odorants including vinegar, banana, mint, rose and coal tar odor. After sniffing each stick, participants should identify each odor freely. The interval between odor presentations was about 30 seconds. The scores ranged from 0 to 5.
3 days before surgery (baseline) and 7 days after surgery (follow-up)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Shanghai 10th People's Hospital

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Massachusetts General Hospital

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Yuan Shen, Shanghai 10th People's Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 1, 2018

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2021

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2022

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 15, 2018

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 15, 2018

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 22, 2018

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 31, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 28, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • dsyy003

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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