The Effects of Lemon Essential Oil Inhalation on Attention in Children With Attention Deficit Hyperactivity Disorder (ADHD)

NCT07586761 | Completed DMC

• 1 other identifier: 10.06.2021-21
• Study Type: interventional
• Target: 52
• Locations: 1 country
• Sites: 1

Brief 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). 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.

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

Outcome Measures

Primary Outcomes (1)

• 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.

  Baseline and Day 30 (after intervention)

Secondary Outcomes (1)

• Change in Benton Visual Retention Test (BVRT) Score

  Baseline and Day 30 (after intervention)

Study Arms (2)

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.

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.

Other: placebo inhalation

Interventions

Lemon Essential Oil Inhalation OTHER

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.

Also known as: Citrus limon aroma, LEO

Lemon Essential Oil Inhalation (LEO)

placebo inhalation OTHER

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.

Placebo Inhalation (Distilled Water)

Eligibility Criteria

• Age: 9 Years - 16 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Başakşehir Çam & Sakura City Hospital: lead

Study Sites (1)

Basaksehir Cam ve Sakura City Hospital

Istanbul, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Attention Deficit Disorder with Hyperactivity

Condition Hierarchy (Ancestors)

Attention Deficit and Disruptive Behavior Disorders; Neurodevelopmental Disorders; Mental Disorders

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: SUPPORTIVE CARE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: SPONSOR

Model Details: 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.

Study Record Dates

• First Submitted: December 24, 2025
• First Posted: May 14, 2026
• Study Start: February 15, 2022
• Primary Completion: September 30, 2023
• Study Completion: September 30, 2023
• Last Updated: May 14, 2026

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)