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.

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.

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

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.