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Ginkgo biloba has been reputed as an aid to brain health and neurological conditions for centuries by traditional doctors. Ginkgo's usefulness for children with attention deficit/hyperactivity disorder has now been confirmed by a clinical study from Germany. This is supported by previous research showing Ginkgo's effects on cognition among the elderly.
The ADHD research comes from the University of Tübingen's Center for Medicine, Society and Prevention.
Researchers tested a Ginkgo biloba extract called EGb761 on 20 children diagnosed with ADHD in an open clinical protocol. The children were given the Ginkgo extract for three to five weeks at a dosage of up to 240 milligrams. This maximum dosage was given to those children who did not have immediate effective responses to a lower dose over the initial period of three weeks.
The researchers utilized clinical assessments to rate the improvement in symptoms along with the Continuous Performance Test (Cue-CNV in the CPT) that tested the brain's electrical activity among the children. The researchers also assessed the children with quality of life testing and the Side Effect Rating Scale.
What is CNV testing?
Contingent negative variation (CNV) testing utilizes magnetoencephalography (MEG) to measure the amplitudes of brain waves that correspond to attention and stimuli. These waves are thought to originate from the premotor cortex.
The researchers found that the Ginkgo extract improved ADHD symptoms among the children. This improvement corresponded with improved CNV results.
Previous research on Ginkgo illustrates its cognitive benefits
This same Ginkgo extract, EGb761 was studied a decade ago at Virginia's Liberty University. Here the researchers tested 262 elderly persons aged 60 or older who scored at least 26 on the Mini-Mental State Exam. For six weeks, half of the group was given 180 milligrams per day of the Ginkgo extract and the other half was given a placebo.
The researchers tested the adults with a battery of testing, including Selective Reminding, Wechsler Adult Intelligence Scale-III Block Design, Digit Symbol-Coding and Wechsler Memory Scale testing. The Ginkgo group scored significantly higher improvements in scores than the placebo group. These included tests on delayed recognition of visual matter, and their general memory responses were improved compared to the placebo group. The researchers concluded:
"Overall, the results from both objective, standardized, neuropsychological tests and a subjective, follow-up self-report questionnaire provided complementary evidence of the potential efficacy of Ginkgo biloba EGb 761 in enhancing certain neuropsychological/memory processes of cognitively intact older adults, 60 years of age and over."
Other studies since this have found similar results, specific to this same Ginkgo extract, EBg761.
From other research it appears the mechanisms of Ginkgo are related to its blocking of the monoamine oxidase enzyme, involved in dopamine production - making it a MAO inhibitor. Ginkgo also appears to neutralize neuron-damaging free radicals. The blocking of monoamine-oxidase slows MPP+ (1-methyl-4-phenylpyridine) and inhibits 6-hydroxydopamine.
Ginkgo is an ancient plant species, and the Ginkgo tree has a long history of medicinal use. Extracts are typically derived from the leaves, but the seeds have also been cooked and used as food in some traditional diets. The Ginkgo trees of Hiroshima were one of the few tree species to survive the nuclear blast.
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Mix JA, Crews WD Jr. A double-blind, placebo-controlled, randomized trial of Ginkgo biloba extract EGb 761 in a sample of cognitively intact older adults: neuropsychological findings. Hum Psychopharmacol. 2002 Aug;17(6):267-77.
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