Background: Current treatment options for attention deficit hyperactivity disorder (ADHD) are limited by factors such as adherence and cost, whilst no treatment options are available for sub-clinical or undiagnosed ADHD. Herbal preparations may therefore offer an alternative approach to the management of symptoms; Aloysia citriodora Paláu (lemon verbena) is a promising candidate.
Aim: To assess the behavioural, cognitive, psychological and physiological effects of 56 days of supplementation with lemon verbena extract (LVE) in children exhibiting symptoms of ADHD at the sub-clinical level.
Methods: This exploratory study followed a randomised, double-blind parallel groups design wherein 120 healthy participants aged 8-17 years received 15 mg/kg bw/d LVE or matched placebo for 56 days. Behavioural, cognitive, mood and physiological measures were collected in the lab at baseline and 28 and 56 days post-dose. Parents also evaluated the child's behaviour throughout the study.
Results: Participants who received LVE reported greater subjective fatigue, defined as reduced energy levels according to the Profile of Mood States subscale, without impairments in cognitive performance across the 56-day intervention and lower depression symptoms on day 56, compared to placebo. The effect of LVE on parent ratings of hyperactive/impulsive behaviour also approached significance with fewer concerns being reported following the active treatment. Exploratory analyses showed further benefits to cognition and mood.
Conclusions: This study revealed novel, beneficial effects of LVE supplementation in children exhibiting a high frequency of behaviours characteristic of ADHD. Overall, LVE was safe and well-tolerated by participants, with no unexpected safety events.
Keywords: ADHD; Aloysia citriodora; Lemon verbena; Lippia citriodora; cognition.