Poster #44 - L-theanine and Caffeine Improve Overall Cognitive Function Scores in Children with Attention Deficit Hyperactivity Disorder

• In Event: 3-206 - Poster Session 13
  In Poster Session: PS 13 Section - Developmental Disabilities

Integrative Statement

Background: Attention deficit hyperactivity disorder (ADHD) is characterized by impaired attention, hyperactivity and impulsivity (DSM-V). ADHD is associated with academic underachievement (Barry et al., 2002). L-theanine and caffeine are two compounds that have been repeatedly demonstrated to improve selective attention in healthy young adults (Kelly et al., 2008; Kahathuduwa et al., 2017 & 2018). Furthermore, L-theanine is well-tolerated by children with ADHD and the adverse effects are minimal (Lyon et al., 2011). However, acute effects of intake of these compounds on cognitive functions of children with ADHD have not been studied. Therefore, as part of a neuroimaging pilot study, we examined the effects of oral administration of L-theanine, caffeine and their combination compared to a placebo on cognitive abilities of boys with ADHD in a placebo-controlled repeated measures crossover trial.
Methods: Five boys (age 9-15 years) who had been diagnosed with ADHD by a psychiatrist and had responded to stimulant medications were recruited. The subjects presented for four intervention visits after refraining from intake of stimulants for ≥24 hours. During the intervention visits, the subjects consumed a 100 ml drink that contained either 2.5 mg/kg body weight of L-theanine; 2 mg/kg body weight of caffeine; their combination; or water in a randomized counter-balanced order. NIH Toolbox Cognition Battery, which includes Dimensional Change Card Sort Test, Flanker Inhibitory Control and Attention Test, Picture Sequence Memory Test, List Sorting Working Memory Test, Pattern Comparison Processing Speed Test, Picture Vocabulary Test and Oral Reading Recognition Test (Zelazo & Bauer, 2013), was administered after 90 minutes of oral intake of each substance. An age-adjusted total cognition composite score was calculated using the raw-scores individual cognitive function tests (Heaton et al., 2014). State version of the State Trait Anxiety Inventory for Children (STAI-CH-S; Spielberger & Edwards, 1973) was administered pre- and 90-minutes post-administration of each substance. Effects of administration of L-theanine, caffeine and their combination on age-adjusted total composite score of the NIH Cognition toolbox were compared with the placebo in a two-level random-effects model constructed using lmerTest package in R, including random intercepts for subjects. Post- vs. pre-intervention change of STAI-CH-S, intervention visit number and squared intervention visit number were included as covariates.
Results: The five subjects (mean age 13.6±2.25 years) completed all measurements. Oral intake of L-theanine, caffeine and L-theanine-caffeine combination resulted in significant improvements of the age-adjusted total cognition composite score compared to the placebo (p = 0.011, p = 0.028 and p = 0.033 respectively; see Table 1). A significant practice effect was apparent as indicated by a significant coefficient of the squared intervention visit number (p = 0.027).
Conclusion: As observed in healthy young adults, oral intake of either of L-theanine and caffeine seems to acutely improve cognitive abilities of children with ADHD. As such, both L-theanine and caffeine could potentially be used to improve performance of children with ADHD, especially when engaging in tasks of high cognitive demand (e.g. learning, test taking). Future studies should aim to explore the cognitive and neurophysiological mechanisms of these potential beneficial effects.

Authors

• Chanaka N. Kahathuduwa, Texas Tech University
  Presenting Author

• Sarah Wakefield, Department of Psychiatry, Texas Tech University Helath Sciences Center
  Non-Presenting Author

• Blake D. West, Texas Tech University - Human Development & Family Studies
  Non-Presenting Author

• Jessica E Blume, Texas Tech University - Human Development & Family Studies
  Non-Presenting Author

• Ann Mastergeorge, Texas Tech University
  Non-Presenting Author