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

8. maj 2026 opdateret af: Başakşehir Çam & Sakura City Hospital

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.

Studieoversigt

Status

Afsluttet

Betingelser

Intervention / Behandling

Detaljeret beskrivelse

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.

Undersøgelsestype

Interventionel

Tilmelding (Faktiske)

52

Fase

  • Ikke anvendelig

Kontakter og lokationer

Dette afsnit indeholder kontaktoplysninger for dem, der udfører undersøgelsen, og oplysninger om, hvor denne undersøgelse udføres.

Studiesteder

Deltagelseskriterier

Forskere leder efter personer, der passer til en bestemt beskrivelse, kaldet berettigelseskriterier. Nogle eksempler på disse kriterier er en persons generelle helbredstilstand eller tidligere behandlinger.

Berettigelseskriterier

Aldre berettiget til at studere

  • Barn

Tager imod sunde frivillige

Ja

Beskrivelse

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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

Studieplan

Dette afsnit indeholder detaljer om studieplanen, herunder hvordan undersøgelsen er designet, og hvad undersøgelsen måler.

Hvordan er undersøgelsen tilrettelagt?

Design detaljer

  • Primært formål: Støttende pleje
  • Tildeling: Randomiseret
  • Interventionel model: Parallel tildeling
  • Maskning: Enkelt

Våben og indgreb

Deltagergruppe / Arm
Intervention / Behandling
Eksperimentel: Lemon Essential Oil Inhalation (LEO)
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.
Andet: Lemon Essential Oil Inhalation
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.
Andre navne:
  • Citrus limon aroma
  • LEO
Placebo komparator: Placebo Inhalation (Distilled Water)
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.
Andet: placebo inhalation
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.

Hvad måler undersøgelsen?

Primære resultatmål

Resultatmål
Foranstaltningsbeskrivelse
Tidsramme
Change in D2 Attention Test Total Performance Score (TN-E)
Tidsramme: 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.
Baseline and Day 30 (after intervention)

Sekundære resultatmål

Resultatmål
Foranstaltningsbeskrivelse
Tidsramme
Change in Benton Visual Retention Test (BVRT) Score
Tidsramme: Baseline and Day 30 (after intervention)
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.
Baseline and Day 30 (after intervention)

Samarbejdspartnere og efterforskere

Det er her, du vil finde personer og organisationer, der er involveret i denne undersøgelse.

Sponsor

Başakşehir Çam & Sakura City Hospital

Datoer for undersøgelser

Disse datoer sporer fremskridtene for indsendelser af undersøgelsesrekord og resumeresultater til ClinicalTrials.gov. Studieregistreringer og rapporterede resultater gennemgås af National Library of Medicine (NLM) for at sikre, at de opfylder specifikke kvalitetskontrolstandarder, før de offentliggøres på den offentlige hjemmeside.

Studer store datoer

Studiestart (Faktiske)

15. februar 2022

Primær færdiggørelse (Faktiske)

30. september 2023

Studieafslutning (Faktiske)

30. september 2023

Datoer for studieregistrering

Først indsendt

24. december 2025

Først indsendt, der opfyldte QC-kriterier

8. maj 2026

Først opslået (Faktiske)

14. maj 2026

Opdateringer af undersøgelsesjournaler

Sidste opdatering sendt (Faktiske)

14. maj 2026

Sidste opdatering indsendt, der opfyldte kvalitetskontrolkriterier

8. maj 2026

Sidst verificeret

1. december 2025

Mere information

Begreber relateret til denne undersøgelse

Nøgleord

Yderligere relevante MeSH-vilkår

Andre undersøgelses-id-numre

  • 10.06.2021-21

Plan for individuelle deltagerdata (IPD)

Planlægger du at dele individuelle deltagerdata (IPD)?

INGEN

IPD-planbeskrivelse

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.

Lægemiddel- og udstyrsoplysninger, undersøgelsesdokumenter

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