Enzogenol for cognitive functioning in traumatic brain injury: a pilot placebo-controlled RCT

Eur J Neurol. 2013 Aug;20(8):1135-44. doi: 10.1111/ene.12099. Epub 2013 Feb 5.


Background and purpose: Enzogenol, a flavonoid-rich extract from Pinus radiata bark with antioxidant and anti-inflammatory properties has been shown to improve working memory in healthy adults. In traumatic brain injury (TBI), oxidation and inflammation have been linked to poorer cognitive outcomes. Hence, this phase II, randomized controlled trial investigated safety, compliance and efficacy of Enzogenol for improving cognitive functioning in people following mild TBI.

Methods: Sixty adults, who sustained a mild TBI, 3-12 months prior to recruitment, and who were experiencing persistent cognitive difficulties [Cognitive Failures Questionnaire (CFQ) score > 38], were randomized to receive Enzogenol (1000 mg/day) or matching placebo for 6 weeks. Subsequently, all participants received Enzogenol for a further 6 weeks, followed by placebo for 4 weeks. Compliance, side-effects, cognitive failures, working and episodic memory, post-concussive symptoms and mood were assessed at baseline, 6, 12 and 16 weeks. Simultaneous estimation of treatment effect and breakpoint was effected, with confidence intervals (CIs) obtained through a treatment-placebo balance-preserving bootstrap procedure.

Results: Enzogenol was found to be safe and well tolerated. Trend and breakpoint analyses showed a significant reduction in cognitive failures after 6 weeks [mean CFQ score, 95% CI, Enzogenol versus placebo -6.9 (-10.8 to -4.1)]. Improvements in the frequency of self-reported cognitive failures were estimated to continue until week 11 before stabilizing. Other outcome measures showed some positive trends but no significant treatment effects.

Conclusions: Enzogenol supplementation is safe and well tolerated in people after mild TBI, and may improve cognitive functioning in this patient population. This study provides Class IIB evidence that Enzogenol is well tolerated and may reduce self-perceived cognitive failures in patients 3-12 months post-mild TBI.

Keywords: brain injury; neurological disorders; randomized clinical trial; rehabilitation; trauma.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accidents, Traffic
  • Adult
  • Brain Injuries / complications*
  • Brain Injuries / psychology
  • Cognition Disorders / drug therapy*
  • Cognition Disorders / etiology*
  • Cognition Disorders / psychology
  • Data Interpretation, Statistical
  • Dietary Supplements*
  • Double-Blind Method
  • Female
  • Flavonoids / adverse effects
  • Flavonoids / therapeutic use*
  • Glasgow Coma Scale
  • Humans
  • Male
  • Memory / physiology
  • Middle Aged
  • Neuropsychological Tests
  • Nonlinear Dynamics
  • Patient Compliance
  • Pilot Projects
  • Post-Concussion Syndrome / drug therapy
  • Post-Concussion Syndrome / psychology
  • Quercetin / adverse effects
  • Quercetin / analogs & derivatives*
  • Quercetin / therapeutic use
  • Treatment Outcome
  • Young Adult


  • Flavonoids
  • enzogenol
  • Quercetin