Wednesday, October 26th, 2011
If the front part of the cerebral cortex is less active then people have less control over their social behaviour and automatically follow their inclinations more. This emerged from a study by Inge Volman that will be published on 25 October in the Journal Current Biology. The research was the first to make use of magnetic stimulation (TMS) to suppress this part at the front of the prefrontal cortex. During TMS a changing magnetic field on the head temporarily influences the activity of the underlying part of the brain.
Study subjects in whom the activity of the prefrontal cortex was temporarily suppressed could control their emotional impulses less well than normal. Their amygdala deep in the brain that is responsible for emotional reactions then becomes extra active. This emerged from the study by Inge Volman and her colleagues from the Behavioural Science Institute and the Donders Institute of Radboud University Nijmegen. This study is important for a good understanding of the role played by various parts of the brain and could in the future contribute to the treatment of aggression and social anxiety disorders.
Approach versus avoidance
Volman allowed the study subjects to perform a so-called approach-avoidance task in which they were shown emotional faces. Normally we withdraw when we see an angry face and try to come closer if we see a happy person. The study subjects were asked to respond in exactly the opposite manner. Using a joystick study subjects had to approach angry faces and push away happy faces. They were significantly worse at doing this after disruption of the aPFC. The emotion area – the amygdala – of the study subjects became extra active.
‘This ties in with what we already knew from animal and patient studies. Instead of just measuring and observing behaviour we can also directly influence brain activity with the help of TMS. Furthermore, combining TMS with fMRI makes the design of this study extra special, as then we can observe the effects in both the behaviour and the brain,’ says Volman.
Even though we do not know exactly how it works, TMS is already used commercially for the treatment of depression. Based on this study are there possible therapeutic applications of TMS in people who have a disrupted control system?
‘The effect of TMS is temporary and that makes it difficult to apply therapeutically. A possible application could be helping people to overcome a certain behaviour. For example, people suffering from a social anxiety disorder have a strong urge to avoid social situations, such as a party. They are often stuck in a vicious circle: as a result of this avoidance they never learn that they can cope with the situation and so the anxiety increases. This avoidance tendency could possibly be reduced with the help of TMS. Then after a treatment the patient might dare go to a party and discover that it was quite an enjoyable experience. He or she might then dare to go to another party without the need for TMS first.’
Anterior Prefrontal Cortex Inhibition Impairs Control over Social Emotional Action. Current Biology, 25 October 2011
Inge Volman, Karin Roelofs, Saskia Koch, Lennart Verhagen, Ivan Toni
Friday, October 21st, 2011
Patirce Wendling-FT. Lauderdale, FLA. What do atypical antipsychotics, an analeptic, and targeted magnets have in common? They all might play a role in the treatment of anorexia nervosa.
“When you have a disorder that is so treatment resistant, it’s like metastatic breast cancer; you have to think outside the box for new interventions,’ Dr. Alan S. Kaplan said at a workshop on eating disorders at the meeting.
Current statistics indicate that 20% of patients who are diagnosed with anorexia are resistant to any intervention, and remain chronically ill and disables. The needs of these patients have been largely neglected by the field, even though their numbers continue to grow because mortality has gradually decreases from 22% in older studies to about 8-10% today, said Dr. Kaplan, the Loretta Anne Rogers Chair in Eating Disorders and professor of psychiatry at the University of Toronto.
In his experience, many of these patients are now in their 40s and 50s, and have been ill for 20-30years. Most of them suffer from significant medical complications, including renal failure, cardiac arrhythmias, and osteoporosis with resulting hip fractures that have left them wheelchair bound.
“They are unbelievably disables,” he said. “They are more disabled on quality of life measurements than a comparative group of schizophrenics in the hospital. It’s a sobering experience to spend time with these patients.”
One novel approach that might be useful is use of repetitive transcranial magnetic stimulation (rTMS), which has been shown to be effective in some patients with depression, schizophrenia, and obsessive-compulsive disorder. Current magnets stimulate superficial cortical areas of the brain, but Dr. Kaplan suggests that a better target might be the insula-a cerebral cortex structure located deep within the lateral fissure that plays a role in interoceptive awareness and motor control.
His group has completed and unpublished meta-analysis of neuroimaging studies in anorexia which provides evidence of over-activity in the insula.
The team members have subsequently contracted with an Israeli biotechnology firm to construct a patented magnet for rTMS the will specifically target the insula. They also plan to launch an open-label pilot trial of rTMS for anorexia.
Thursday, October 13th, 2011
Deep transcranial magnetic stimulation (TMS) is a medical application of electromagnetic technology. It essentially relies on the fact that neurons communicate via chemical-electric signals; hence, like other electrical signals, neuronal communication should be able to be influenced by external magnetic fields, or pulses.
The Jerusalem-based company Brainsway has been applying deep TMS technology to potentially treat a number of clinical conditions, some of which have been previously reported here in Medgadget, such as depression, attention deficit disorder, and smoking addiction. Now, the company reports initial positive findings in a small trial of Alzheimer’s patients treated with deep TMS.
According to Brainsway’s press release:
The interim results are for 24 patients that were divided into three groups: a sham stimulation control group, a low-frequency (1 Hz) treatment group and a high-frequency (10 Hz) treatment group. Each subject received treatment over 8 weeks, and the efficacy of the treatment was evaluated both during the trial and over the course of the subsequent 8-week period.
The treatment was well-tolerated by all subjects, with no side-effects, except for one incident involving a sham control subject, which the principal investigator believes to be unrelated to the treatment.
The trial used the Alzheimer’s Disease Assessment Scale – Cognitive (ADAS-Cog) test (the main efficacy scale used in Alzheimer’s disease clinical trials), as well as additional accepted scales of disease severity (CGI, ADL, CDR) and a quality-of-life scale (QoL Caregiver Scale) to assess the efficacy of treatment. These are the main assessment scales used to evaluate efficacy in the literature.
Analysis of ADAS-Cog results revealed a 4.2-point improvement in the high-frequency treatment group, compared with a 1.8-point improvement in the sham control group, and a 1.4-point deterioration in the scores of the low-frequency treatment group, the latter occurring mainly during the 8 weeks post treatment. In addition, in the high-frequency treatment group, severity of cognitive impairment at entry into the trial was correlated with clinical improvement (the more severe the cognitive impairment, the more the patient improved following treatment).
CDR, ADL, CGI and QoL Caregiver Scale scores indicated that high-frequency treatment halted the deterioration of the disease and even produced a moderate improvement relative to sham treatment. Similar to the ADAS-Cog test results, these scores also indicated a worsening in the condition of patients treated with low-frequency electromagnetic stimulation.
The principle investigator commented, “The interim results from the trial indicate that Deep TMS therapy for Alzheimer’s disease patients is safe and side-effect-free. Although the small sample size somewhat hampers our ability to draw any definitive conclusions concerning treatment efficacy, the results nonetheless suggest that high-frequency treatment leads to improvement on Alzheimer’s disease assessment scales, whereas low-frequency and sham treatment do not.”