Focus on Alternative and Complementary Therapies
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Focus Alternat Complement Ther©2005 Pharmaceutical Press
Focus Altern Complement Ther 2006; 11: 22–3
Extracts of Ginkgo biloba are widely used for the treatment of cognitive impairment. Recent reviews showed that Ginkgo biloba is effective in enhancing cognition in healthy and cognitively impaired subjects. Apart from this evidence of therapeutic efficacy there are a number of studies suggesting beneficial basic physiological effects. Although both groups of studies yielded encouraging results, there is a gap between ‘macroscopic’ (therapeutic) evidence and ‘microscopic’ knowledge on physiological changes. In this review we look at specific cognitive effects in order to help to overcome this gap.
We selected randomised control group trials reporting specific neuropsychological changes (psychometric tests). Effects in different cognitive domains are listed using a widely accepted taxonomy (memory, attention, intelligence, executive functions). This classification further distinguishes dissociable aspects within each of these four cognitive domains, i.e. memory (long-term vs. short-term; working memory), attention (sustained, selective, divided attention and alertness), mental capability (fluid vs. crystallised intelligence) and executive functions (planning and problem-solving).
Effects are most pronounced in speed-related components of working and long-term memory (verbal/non-verbal episodic materials). Interestingly, qualitative aspects of performance are altered in different cognitive domains (reduction of errors).
We conclude that these specific effects were formerly clouded by the heterogeneity of trials and some methodological problems. Finally, we show that this working and long-term memory interpretation of effects is compatible with beneficial actions on the basic physiological (‘microscopic’) level. Our review further suggests that most beneficial effects are exerted on those neuropsychological functions that are more likely to be affected by healthy and accelerated cognitive ageing.
