Monday April 12 2010
Muscle-freezing botox injections have grown in popularity
"Botox can lose you your friends,” according to the Metro, which said that the anti-wrinkle injections could “damage your social life and emotions”. According to the newspaper, using the popular cosmetic jab could make users “take longer to frown or look sad” and that they “may be unable to show empathy when told of the death of a friend”.
The small study behind this and other news reports found that people who have had Botox treatment for frown lines read angry and sad sentences slower after treatment than before it. Conversely, the treatment had no effect on the reading speed of happy sentences.
Overall, it is questionable whether these findings, based on reading speed, can be interpreted to imply that a volunteer’s emotional processing was different before and after treatment. What is more certain is that this study does not provide evidence that people who have Botox will lose their friends, as many media reports have implied.
Where did the story come from?
The study was carried out by Dr David Havas and colleagues from the University of Wisconsin-Madison, Arizona State University and the University of Chicago. The US study was funded by the National Science Foundation, National Institute of Mental Health and Research to Prevent Blindness. The study is available prior to full publication in the peer-reviewed medical journal Psychological Science.
Newspapers have generally overstated the findings of this study. This research provides no evidence that people who have Botox treatment have fewer friends or a poorer social life.
What kind of research was this?
This observational study looked at a theoretical measure of emotional response time in 41 healthy people who received Botox injections for the first time. Researchers observed the time the group took to read sentences describing angry, happy and sad situations before and after Botox treatment for frown lines. The researchers say that by measuring the change in reading times, they could comment on how Botox affects processing of angry, happy and sad sentences.
What did the research involve?
The 41 female participants were recruited through cosmetic surgery clinics. They were given $50 towards the cost of their treatment for participation in two study sessions. In the first session, immediately before their Botox treatment, the women were given 20 happy, 20 sad and 20 angry sentences to read on a computer. They were instructed to press a key on the keyboard when they had finished reading the sentence. Some sentences were followed by a yes or no question, which the researchers say was inserted to encourage comprehension.
A second study session was scheduled for two weeks after the Botox treatment, in which the participants read 60 remaining sentences. At each session, the last 16 participants also completed a questionnaire that assessed their positive and negative emotions.
The researchers used a technique called regression analysis to assess the contribution of different factors to reading time, namely in which session a question was asked and the emotion it reflected. The researchers also undertook a separate analysis to determine whether treatment-related anxiety might be responsible for any change in the way the sentences were read.
What were the basic results?
The study found that, on average, overall reading times were longer for angry sentences than for happy or sad ones. Response time was also linked to both session number and the sentence emotion, suggesting that performance was different before and after the Botox treatment.
Angry and sad sentence reading times increased by about 0.2 to 0.3 seconds following Botox treatment. There was no difference in happy sentence reading time. Pre-treatment anxiety was not significantly related to the change in reading times between the sessions.
The researchers discuss reasons why Botox may affect the processing of emotions, drawing on the findings of other researchers, both in animal and human studies.
How did the researchers interpret the results?
The researchers concluded that their study shows that paralysis of facial muscles “selectively hinders emotional language processing”. They say that the reading time of sentences was increased if the sentiment they conveyed would usually be expressed using the muscles paralysed by Botox.
This small observational study measured reading time which, the researchers say, is a proxy for emotional processing. They say that previous research has linked the ability to interpret a negative emotion, such as sadness and anger, to the ability to physically express the emotion facially. Based on this theory, they investigated whether the interpretation of these negative emotions was affected if physical expression was paralysed by Botox.
Overall, this research has some limitation, principally the assumption by the researchers that reading time is the same as emotional processing. It is not clear that this has been conclusively established by previous studies. Other points to consider when interpreting these findings include the small sample size and the potential for unmeasured confounders, which may have affected the outcome. Equally, while the researchers attempted to rule out pre-treatment anxiety as a cause of faster reading times before treatment, other emotions may have been at play that would be difficult to measure.
The findings of this research have been overstated by the media. The researchers say that their study “raises questions about the effects of Botox on […] emotional reactivity”, whereas news coverage interpreted this to suggest that Botox could damage personal relationships. Such claims seem unfounded given that the research did not assess sociability or popularity of the participants (either before or after treatment), nor did it ask other people to rate the facial expressions of the people treated with Botox.