Attention Deficit Disorder With Hyperactivity (ADHD)NCT07586761
The Effects of Lemon Essential Oil Inhalation on Attention in Children With Attention Deficit Hyperactivity Disorder (ADHD)
A study testing Lemon Essential Oil Inhalation in people with Attention Deficit Disorder With Hyperactivity (ADHD) and Sustained Attention, run by Başakşehir Çam & Sakura City Hospital at 1 site in Turkey (Türkiye).
Trial summary
This randomized, placebo-controlled clinical trial aims to evaluate the acute effects of lemon essential oil inhalation on sustained attention and visual memory in children diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD). Read more about this study
- Who is it for?
- Ages 9 to 16 yearsHealthy volunteers can take part
- Conditions the study is for
- Attention Deficit Disorder With Hyperactivity (ADHD), Sustained Attention, Aromatherapy
- What is being tested?
- Lemon Essential Oil Inhalation
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 52 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 15 Feb 2022to 30 Sep 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 9 to 16 years
- All sexes
- Healthy volunteers accepted
- Child
Who may be able to join
- Children aged 9 to 16 years
- Diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) based on DSM-5 criteria
- Medication-naive (not currently using or previously treated with pharmacological agents for ADHD)
- No chronic medical or psychiatric comorbidities
- Capable of completing standardized cognitive assessments (e.g., D2 Attention Test, Benton Visual Memory Test)
- Written informed consent obtained from a parent or legal guardian
- Written assent obtained from the child
Who cannot join
- Lack of written parental consent or child assent
- Inability to comply with the study protocol (e.g., refusal to complete cognitive testing or intervention procedure)
- Current or prior use of ADHD medication
- Presence of moderate-to-severe ADHD symptoms requiring immediate pharmacological treatment (based on AACAP 2020 and NICE 2019 guidelines)
- Presence of any chronic medical or psychiatric comorbid condition
- Diagnosis not confirmed by a board-certified child and adolescent psychiatrist
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Basaksehir Cam ve Sakura City Hospital
Istanbul
About this study
Official title: Lemon Essential Oil Inhalation Improves Sustained Attention in Children With Attention-Deficit/Hyperactivity Disorder: A Placebo-Controlled Trial
This randomized, placebo-controlled clinical trial aims to evaluate the acute effects of lemon essential oil inhalation on sustained attention and visual memory in children diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD). Fifty-two medication-naive children aged 9-16 were randomized to receive either lemon oil or placebo inhalation before cognitive assessments. Primary outcome was sustained attention performance. The study found significant improvements in attention scores in the lemon oil group.
Read the detailed description
This randomized, placebo-controlled, single-blind clinical trial investigates the acute effects of lemon essential oil (LEO) inhalation on sustained attention and visual memory in children with attention-deficit/hyperactivity disorder (ADHD). Essential oils, particularly those rich in monoterpenes such as limonene, have demonstrated neuroactive properties through cholinergic modulation and limbic-prefrontal engagement via the olfactory pathway.
Fifty-two children aged 9-16 years, newly diagnosed with ADHD and not receiving any pharmacological treatment, were randomized to either the LEO group or the placebo group. Participants in the LEO group inhaled 5 drops of 100% pure Citrus limon essential oil via a cotton pad for five minutes prior to cognitive testing. The placebo group received an identical application with odorless distilled water.
Cognitive performance was assessed at baseline and 30 days later using the D2 Attention Test (primary outcome) and the Benton Visual Memory Test (secondary outcome). The entire intervention was conducted under standardized conditions, with blinded outcome assessment and strict adherence to procedural fidelity.
This study is the first to evaluate the short-term cognitive effects of lemon essential oil inhalation in children with clinical ADHD and aims to provide evidence for potential non-pharmacological support strategies.
- Conditions
- Attention Deficit Disorder With Hyperactivity (ADHD), Sustained Attention, Aromatherapy, Essential Oil, Non-Pharmacological Interventions
- Being tested
- Lemon Essential Oil Inhalation, placebo inhalation
- Keywords
- Pediatric Neuropsychology, Non-Pharmacological Interventions, Attention Deficit Disorder with Hyperactivitiy (ADHD), Aromatherapy, Essential Oils
- Medical subject headings
- Attention Deficit Disorder with Hyperactivity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Lemon Essential Oil InhalationOther
Also called Citrus limon aroma, LEO
This intervention consists of a single-session, short-term olfactory exposure to 100% pure lemon essential oil (Citrus limon, ISO 9235 compliant, GC-MS confirmed composition: limonene 67.2%, β-pinene 12.3%, γ-terpinene 9.8%). Five drops were applied to a sterile cotton pad and held approximately 5 cm from the participant's nose. Participants inhaled the aroma for 5 minutes under direct supervision in a quiet, odor-free clinical setting. This intervention was administered immediately prior to standardized neuropsychological assessments measuring attention and visual memory. No ingestion or topical application occurred.
placebo inhalationOther
The placebo condition involved the same protocol as the intervention group, using five drops of distilled water applied to a sterile cotton pad. The pad was held approximately 5 cm from the participant's nose, and inhalation lasted for 5 minutes. The procedure was designed to mimic the intervention without olfactory stimulation, ensuring consistency in timing, setting, and administration method.
| Study group | Role | What they receive |
|---|---|---|
| Lemon Essential Oil Inhalation (LEO) | Experimental | Participants in this arm received a single-session inhalation of 100% pure lemon essential oil (Citrus limon) via a sterile cotton pad. Five drops of essential oil were applied to the pad, which was held approximately 5 cm from the participant's nose. The child inhaled the scent for 5 minutes under supervision in a clinical setting. Neuropsychological testing (D2 Attention Test and Benton Visual Memory Test) followed immediately after inhalation. Receives: Other: Lemon Essential Oil Inhalation |
| Placebo Inhalation (Distilled Water) | Placebo comparator | Participants in this arm received a single-session inhalation of distilled water as placebo. Five drops of distilled water were applied to a sterile cotton pad, which was held approximately 5 cm from the participant's nose. The child inhaled the scentless solution for 5 minutes under supervision. Neuropsychological testing (D2 Attention Test and Benton Visual Memory Test) followed immediately after inhalation. Receives: Other: placebo inhalation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in D2 Attention Test Total Performance Score (TN-E)
The D2 Attention Test evaluates sustained attention and concentration performance. The TN-E (Total Number of Correct Items minus Errors) score reflects attentional capacity. A higher post-intervention TN-E score indicates improved attention. The difference between baseline and Day 30 scores will be compared between the lemon essential oil group and placebo group.
Measured: Baseline and Day 30 (after intervention)
Secondary outcomes (1)
Change in Benton Visual Retention Test (BVRT) Score
The Benton Visual Retention Test assesses visual memory and visuospatial construction skills. Scores range based on correct reproductions of geometric figures. The change in BVRT scores from baseline to Day 30 will be analyzed to assess the impact of lemon essential oil inhalation versus placebo.
Measured: Baseline and Day 30 (after intervention)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 May 2026
- Study start15 Feb 2022
- Primary completion30 Sep 2023
- Study completion30 Sep 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Attention Deficit Disorder With Hyperactivity (ADHD)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- This study employed a randomized, single-blind, parallel-group design with two arms: one group received inhalation of lemon essential oil (LEO), and the other received placebo (distilled water). Participants were randomly assigned to either group, and the intervention was administered individually. Both groups underwent baseline and post-intervention neuropsychological testing using standardized assessments. The study assessed the acute effects of a single-session inhalation intervention.
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 52 participants (actual)
Sponsor and investigators
- Lead sponsor
- Başakşehir Çam & Sakura City Hospital
- Sponsor type
- Other government
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07586761
- Sponsor's protocol ID
- 10.06.2021-21
- Status last verified
- Dec 2025
- First submitted
- 24 Dec 2025
- Last updated
- 14 May 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data (IPD) will not be shared for this study due to ethical considerations, privacy protection regulations involving minors, and the absence of prior consent for data sharing beyond the scope of this trial. Additionally, the study was conducted with a small sample size from a single center, limiting the generalizability and reuse of anonymized data for broader analysis.
Study at a glance
From the registry record, last updated by the sponsor on 14 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Lemon Essential Oil Inhalation Improves Sustained Attention in Children With Attention-Deficit/Hyperactivity Disorder: A Placebo-Controlled Trial
- ClinicalTrials.gov ID
- NCT07586761
- Acronym / sponsor ID
- 10.06.2021-21
- Conditions
- Attention Deficit Disorder With Hyperactivity (ADHD), Sustained Attention, Aromatherapy, Essential Oil, Non-Pharmacological Interventions
- Keywords
- Pediatric Neuropsychology, Non-Pharmacological Interventions, Attention Deficit Disorder with Hyperactivitiy (ADHD), Aromatherapy, Essential Oils
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 52 participants (actual)
- Lead sponsor
- Başakşehir Çam & Sakura City HospitalOther government
- Study start
- 15 Feb 2022 (actual)
- Primary completion
- 30 Sep 2023 (actual)
- Study completion
- 30 Sep 2023 (actual)
- First posted
- 14 May 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This randomized, placebo-controlled clinical trial aims to evaluate the acute effects of lemon essential oil inhalation on sustained attention and visual memory in children diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD). Fifty-two medication-naive children aged 9-16 were randomized to receive either lemon oil or placebo inhalation before cognitive assessments. Primary outcome was sustained attention performance. The study found significant improvements in attention scores in the lemon oil group.
Detailed description
This randomized, placebo-controlled, single-blind clinical trial investigates the acute effects of lemon essential oil (LEO) inhalation on sustained attention and visual memory in children with attention-deficit/hyperactivity disorder (ADHD). Essential oils, particularly those rich in monoterpenes such as limonene, have demonstrated neuroactive properties through cholinergic modulation and limbic-prefrontal engagement via the olfactory pathway.
Fifty-two children aged 9-16 years, newly diagnosed with ADHD and not receiving any pharmacological treatment, were randomized to either the LEO group or the placebo group. Participants in the LEO group inhaled 5 drops of 100% pure Citrus limon essential oil via a cotton pad for five minutes prior to cognitive testing. The placebo group received an identical application with odorless distilled water.
Cognitive performance was assessed at baseline and 30 days later using the D2 Attention Test (primary outcome) and the Benton Visual Memory Test (secondary outcome). The entire intervention was conducted under standardized conditions, with blinded outcome assessment and strict adherence to procedural fidelity.
This study is the first to evaluate the short-term cognitive effects of lemon essential oil inhalation in children with clinical ADHD and aims to provide evidence for potential non-pharmacological support strategies.
Study design
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- This study employed a randomized, single-blind, parallel-group design with two arms: one group received inhalation of lemon essential oil (LEO), and the other received placebo (distilled water). Participants were randomly assigned to either group, and the intervention was administered individually. Both groups underwent baseline and post-intervention neuropsychological testing using standardized assessments. The study assessed the acute effects of a single-session inhalation intervention.
| Arm | Type | Receives |
|---|---|---|
| Lemon Essential Oil Inhalation (LEO) | Experimental | Other: Lemon Essential Oil InhalationParticipants in this arm received a single-session inhalation of 100% pure lemon essential oil (Citrus limon) via a sterile cotton pad. Five drops of essential oil were applied to the pad, which was held approximately 5 cm from the participant's nose. The child inhaled the scent for 5 minutes under supervision in a clinical setting. Neuropsychological testing (D2 Attention Test and Benton Visual Memory Test) followed immediately after inhalation. |
| Placebo Inhalation (Distilled Water) | Placebo comparator | Other: placebo inhalationParticipants in this arm received a single-session inhalation of distilled water as placebo. Five drops of distilled water were applied to a sterile cotton pad, which was held approximately 5 cm from the participant's nose. The child inhaled the scentless solution for 5 minutes under supervision. Neuropsychological testing (D2 Attention Test and Benton Visual Memory Test) followed immediately after inhalation. |
Who may qualify
- Ages
- 9 to 16 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child
Key inclusion criteria (7 listed)
- Children aged 9 to 16 years
- Diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) based on DSM-5 criteria
- Medication-naive (not currently using or previously treated with pharmacological agents for ADHD)
- No chronic medical or psychiatric comorbidities
- Capable of completing standardized cognitive assessments (e.g., D2 Attention Test, Benton Visual Memory Test)
Key exclusion criteria (6 listed)
- Lack of written parental consent or child assent
- Inability to comply with the study protocol (e.g., refusal to complete cognitive testing or intervention procedure)
- Current or prior use of ADHD medication
- Presence of moderate-to-severe ADHD symptoms requiring immediate pharmacological treatment (based on AACAP 2020 and NICE 2019 guidelines)
- Presence of any chronic medical or psychiatric comorbid condition
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Lemon Essential Oil InhalationAlso: Citrus limon aroma, LEOThis intervention consists of a single-session, short-term olfactory exposure to 100% pure lemon essential oil (Citrus limon, ISO 9235 compliant, GC-MS confirmed composition: limonene 67.2%, β-pinene 12.3%, γ-terpinene 9.8%). Five drops were applied to a sterile cotton pad and held approximately 5 cm from the participant's nose. Participants inhaled the aroma for 5 minutes under direct supervision in a quiet, odor-free clinical setting. This intervention was administered immediately prior to standardized neuropsychological assessments measuring attention and visual memory. No ingestion or topical application occurred. | Other | Lemon Essential Oil Inhalation (LEO) |
| placebo inhalationThe placebo condition involved the same protocol as the intervention group, using five drops of distilled water applied to a sterile cotton pad. The pad was held approximately 5 cm from the participant's nose, and inhalation lasted for 5 minutes. The procedure was designed to mimic the intervention without olfactory stimulation, ensuring consistency in timing, setting, and administration method. | Other | Placebo Inhalation (Distilled Water) |
Primary outcome
Change in D2 Attention Test Total Performance Score (TN-E)
Time frame: Baseline and Day 30 (after intervention)
The D2 Attention Test evaluates sustained attention and concentration performance. The TN-E (Total Number of Correct Items minus Errors) score reflects attentional capacity. A higher post-intervention TN-E score indicates improved attention. The difference between baseline and Day 30 scores will be compared between the lemon essential oil group and placebo group.
1 secondary outcome
Change in Benton Visual Retention Test (BVRT) Score
Time frame: Baseline and Day 30 (after intervention)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 May 2026.
- Individual participant dataSharing planned: No. Individual participant data (IPD) will not be shared for this study due to ethical considerations, privacy protection regulations involving minors, and the absence of prior consent for data sharing beyond the scope of this trial. Additionally, the study was conducted with a small sample size from a single center, limiting the generalizability and reuse of anonymized data for broader analysis.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Lemon Essential Oil Inhalation in people with Attention Deficit Disorder With Hyperactivity (ADHD) and Sustained Attention, run by Başakşehir Çam & Sakura City Hospital at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 14 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in D2 Attention Test Total Performance Score (TN-E) (time frame: Baseline and Day 30 (after intervention)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 May 2026.