The study, which was headed up by Matteo Caleo of the Italian National Research Council's Institute of Neuroscience, is said to show for the first time that the botulinum toxin may affect the brain. The rat study showed that only a fraction of the toxin was carried through to the proteins and nerves in the brain, with the rest remaining at the injection site. Findings show cause for 'concern' But despite the fact that the tiny amount of toxin that was transferred to the brain area during the injection process having no noticeable affect on the rats' behaviour, Caleo says that the findings still show cause for 'concern'. Although the amount of Botox used in anti-wrinkle procedures is relatively small, Caleo says that it will still be important to carry out further research to better understand the migration of the toxin through brain nerves as well as the specific impact on humans. The study, which was published in the Journal of Neuroscience this week, entailed rats being injected with botulinum neurotoxin around the whisker muscles of the face. Three days after the injections the team assessed the impact the injections had had on the connected brain areas, finding that diluted amounts of the toxins had reached the related brain cells. More research needed As well as having specific medical applications such as the treatment of facial ticks, Botox has seen huge worldwide growth as a non-invasive anti-wrinkle treatment. "These findings reveal a novel pathway of botulinum trafficking in neurons and have important implications for the clinical uses of this neurotoxin," the study concluded. Although the study findings might have some positive applications for research into the treatment of overactive brain neurons, the findings may turn out to have less positive repercussions for individuals seeking the treatment for cosmetic reasons. In Europe Botox has really taken off in recent years, with British consumers leading the way in the take up of the treatment. The Harley Medical Group estimates that in the past two years the number of non-surgical procedures such as Botox and collagen fillers has more than doubled to reach 472,000 in 2007, compared to 230,000 in 2005.