Can Botox Cosmetic Affect the Brain?

It is extremely unlikely that Botox could impact brain function from use on the forehead. The studies that you mention were done in a rodent model.

Hello Devora,
Please be at ease about Botox and your brain!
The study you are referring to was Published in the Journal of Neuroscience earlier this year. The study was conducted in Italy and involved scientists injecting Botox into mice and rats by their whiskers and portions of the brain itself (hippocampus).
The study found that certain proteins that result from the actions of Botox were detected in the brain tissue of the mice and rats. The theory is that the Botox travels from the whisker muscles into the nerves and back into the brain tissue. On the surface this is very scary sounding and cause for concern!
However, it is important to note that the physiology of mice and rats is not the same as humans and therefore needs to be taken into account. In studies with primates who have a much more similar physiology to humans these same concerns about Botox have not been seen. It is also very important to note that the Botox used in the study was formulated in the lab - making it different than the botox that is used cosmetically (Botox for human use is made by Allergan Corp. under strict clinical guidelines).
Another very important point is that there are no muscles in the brain itself - and while Botox can have some impact on nerve to nerve transmission, it's main effect is to weaken muscles by preventing a chemical that triggers the muscle to move from working properly. So being that there are no muscles in the brain any concerns about muscle weakness there is not valid.
Clearly more studies need to be done to validate and clarify the findings of this one paper. Hundreds of other papers, millions of patients and years of clinical use clearly and strongly indicate that Botox is safe to use in humans.
Bottom line: Botox used in appropriate doses has been shown to be very safe and effective in humans. Always go to a board certified physician for your Botox and try to space the treatments apart as far as possible.
Very interesting topic and I am sure that this study will lead to further studies which is always a good thing for both Patients and Physicians.