Botox injections in the forehead may impair a person’s interpretation of facial expressions, according to a new study. Brain scans showed that when people who had Botox injections viewed emotional facial expressions, they exhibited altered activity in their amygdala – an area of the brain involved in processing fearful and threatening stimuli.

Researchers injected Botox into the glabellar muscles (responsible for frowning) of 10 women. Using functional magnetic resonance imaging, they measured the women’s brain activity while viewing emotional faces, both before and after the injections.

They found that activity in the amygdala was altered when viewing both happy and angry faces. Similarly, activity in the fusiform gyrus (an area of the brain involved in the processing of faces) was altered when viewing happy faces.

Botox is the tradename for botulinum toxin A, a prescription medication derived from a neurotoxin produced by the bacterium Clostridium botulinum. It is commonly used to temporarily reduce the appearance of skin wrinkles and works by inhibiting the release of acetylcholine (a neurotransmitter) at motor nerve endings.

The findings from this small study suggest that Botox injections in the forehead impair the interpretation of emotional expressions. They also support what is referred to as the facial feedback hypothesis, which asserts that when we see an emotional expression on a face, we respond by trying to recreate the expression. Doing so helps us identify and experience the emotions we see. Larger studies are needed to confirm these findings.

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