Focus on Alternative and Complementary Therapies
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Focus Alternat Complement Ther©2005 Pharmaceutical Press
Focus Altern Complement Ther 2002; 7: 109–10
Lemon balm (Melissa officinalis) has been used in medical herbalism for at least two millennia, and contemporaneously for its purported sedative–hypnotic properties. The possibility of cognitive and mood effects following single doses of M. officinalis in isolation has not previously been investigated and formed the focus of the present study.
Using a placebo-controlled, double-blind, balanced, crossover design, twenty participants received 300, 600 and 900 mg of a standardised extract of M. officinalis or a placebo, on different days, each separated by a 7-day washout period. Treatment order followed a Latin squares design. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery immediately prior to treatment and at 1 h, 2.5 h, 4 h and 6 h thereafter. The primary outcome measures were four aspects of cognitive performance derived by factor analysis of CDR subtests, and subjective mood ratings from Bond–Lader visual analogue scales.
There were a number of significant changes in these measures following treatment with M. officinalis. The most striking of these included a sustained increase in ‘accuracy of attention’ following 600 mg Melissa, and time- and dose-specific reductions in both ‘secondary memory’ and ‘working memory’ factors. Self-rated ‘alertness’ was significantly reduced at all time points following the highest dose, while ‘calmness’ was elevated at the earliest time-points by the lowest dose.
To the best of our knowledge, these results represent the first systematic evidence that M. officinalis alone is capable of acute modulation of mood and cognition in humans.
