Glabellar botolinum toxin (BTX) injections might have an effect on the central nervous system and could help with the treatment of borderline personality disorder – a recent study by German scientists concluded. Functional magnetic resonance imaging provided the first evidence showing how BTX injections might modify the behavioural and neurobiological aspects of this common condition. These new findings are in line with previous studies on how BTX could be used to treat mental health problems such as depression and anxiety.
In a joint study, recently published in the journal Scientific Reports, researchers from the Asklepios Campus Hamburg of Semmelweis University and the Hannover Medical School examined how BTX injected in the forehead muscles (glabellar area) might affect the processing of emotional stimuli and impulsive behaviour, semmelweis.hu wrote.
The research involved conducting functional magnetic resonance imaging (fMRI) on 45 women suffering from borderline personality disorder (BPD) – after some of them received BTX injections and others received acupuncture. Before the treatment and 4 weeks later the participants were given a so-called emotional go/no go task where they had to control their reactions to certain cues while seeing pictures of faces with different emotional expressions presented to them on a computer screen – while the researchers scanned their brains.
Dr. Axel Wollmer from Semmelweis University’s Asklepios Campus in Hamburg, senior author of the study said:
„BPD is one of the most common personality disorders with symptoms of emotional instability and impulsive behaviour. Patients suffering from BPD experience an excess of negative emotions like anger and fear. Based on previous studies our hypothesis was that relaxing the muscles in the forehead with BTX will interrupt a feedback loop between the face and the brain and thereby reduce these negative emotions.”
The fMRI scans of the injected patients showed decreased activity in the so-called amgydala region of the brain which is responsible for processing negative emotions.
Dr. Wollmer added:
We also found improvement in the symptoms of the control group treated with acupuncture, however not the neural modifications on the fMRI scans, which were present only in the BTX group. The images showed a reduction in the activity of the amygdala in response to emotional stimuli, which is often exaggerated in BPD patients.
The researchers also noticed that BTX reduced the patients’ impulsive behaviour in the go/no go task and it correlated with the activation of prefrontal areas in the brain that are involved in inhibitory control.
The facial feedback hypothesis has been leading the way in BTX research over the last decade. Emotions expressed on the face affect our mental state. Negative emotions such as anger, sadness, or fear often generate vertical wrinkles between the eyebrows. When treated with BTX the underlying muscles are paralysed in this glabellar region which, according to the facial feedback hypothesis, also cuts back the intensity of the expressed emotions.
But previous research also highlighted that the feedback between muscles and brain might not only work in the glabellar region.
In a study in 2021 the German scientists in collaboration with the University of California San Diego, found that BTX can also mitigate anxiety disorders. They analysed the U.S. Food and Drug Administration (FDA) database, where nearly 40,000 people registered their experiences after BTX treatment. The researchers focused on positive side effects of BTX injections which were administered not only for cosmetic use in the forehead area, but to head muscles for migraines, upper and lower limb muscles for spasms and neck muscles for torticollis. They found that anxiety disorders were 22 to 72 percent less common in patients with BTX than in those who had received other therapies for the same conditions.
The scientists therefore concluded that either there is an overall body feedback where the areas treated with BTX communicate with the brain – or the botulinum toxin somehow travels and reaches the central nervous system.
Based on the same database, similar research was conducted in 2020 about the possible antidepressant effects of BTX injections. This showed that BTX could be used not only to treat depression as several previous studies had already suggested – but it might also have a protective effect against the condition.
Dr. Axel Wollmer said:
„The World Health Organization estimates that the number of people suffering from depression is approximately 280 million. Established treatments such as psychotherapy or antidepressants don’t work sufficiently for about one third of the patients so there is a need to develop novel treatment options, and this is where BTX injections could have a role.”
Most of the research in this field got as far as phase 2, but a long-awaited phase 3 trial would be necessary to confirm the possible positive effects of BTX on mental illnesses.
Asklepios Campus Hamburg (ACH) of Semmelweis University, Budapest was founded in 2008 as an off-campus program for the university. After two years of theoretical training, from the third year students of the German-language programs at Semmelweis University can continue their studies at ACH. In the summer of 2022, 54 students graduated in Hamburg and together with the graduates in Hungary, a total of 187 medical and dental students were awarded doctorates in the German-language program of the university.