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Cranial nerve stimulation for less anxiety

People appear to release their feelings of anxiety more quickly when the vagus nerve in the brain is stimulated with a device in the ear. In his doctoral research at Clinical Psychology, Andreas Burger examined new possibilities for treating symptoms of anxiety. PhD defence on 15 May.

People often struggle with anxiety symptoms that restrict them in their daily lives. Burger has found that stimulation of the cranial nerve has beneficial effects in people with epilepsy. This requires a surgical intervention in the case of patients who are resistant to the standard treatment for epilepsy and depression. Recently, other methods of stimulating this nerve have been sought that do not require any surgical intervention. A device the size of a mobile telephone administers electric shocks to the ear, comparable to small needle pricks. Burger’s PhD research  continues this search.

Anxiety reduces more rapidly

The participants in the study are repeatedly shown two pictures. An irritating electric shock is administered to the wrist when one of the two pictures is shown. After a time, people exhibit heightened anxiety for that picture, even without the shock: a classic Pavlov reaction. When the researchers subsequently show this picture multiple times without administering the shock, the individual’s fear gradually decreases. Burger: ‘That is the principle that underpins many psychological treatments for anxiety: repeatedly exposing the patient to what he or she is afraid of. That is why we also call it exposure therapy.’

If, while the anxiety is fading, Burger simultaneously stimulates the vagus nerve of the test subject with small shocks in the ear, the process in which the anxiety reduces is accelerated. ‘The nerve stimulation helps you to learn more quickly not to associate the picture with the shock,’ Burger summarises his findings. ‘Although we’restill not certain about it, I’m hopeful because of how simple it is to stimulate the vagus nerve.’

No physiological reactions

Burger’s research suggests that nerve stimulation via the ear could potentially benefit the treatment of anxiety. With his findings, he is taking a significant initial step towards this ‘non-invasive’ nerve stimulation in the treatment of anxiety symptoms. He believes that this could lead to more treatment options in the long term. However, he does not wish to raise patients’ expectations unduly: ‘We may have found that the anxiety diminishes faster with nerve stimulation, but we did not see this reflected in heart rate or skin conductance. We also measured these physiological responses during the anxiety task, by attaching electrodes to the test candidates while they carried out the computer task in the lab.’

‘Stepping stone’

Burger is well aware that the research is still in its infancy. A number of issues still have to be resolved, such as: what is the underlying mechanism? And with what frequency and intensity should you apply nerve stimulation? Rather, he sees his research as a ‘stepping stone’. ‘It is important to find out now whether this method works and what the mechanisms behind this nerve stimulation are.’ Burger will continue his research as a postdoc at KU Leuven, the institution with which he has been associated since the start of his PhD programme.

About the research

Critical

Burger believes his greatest asset in conducting his PhD research was his critical attitude, and also welcomes the fact that there was room for expressing criticism. ‘My field of research is highly influenced by industry, just as is the case in medicine. In addition, positive affirmations are usually found in the literature, while conflicting interests, negative feedback and results tend to be hidden away. ‘And in the field of psychological research there is still a lot to be done,’ Burger believes.

Pre-registration

The same applies to pre-registering psychological research. This has long been mandatory for medical research: prior to a study, the researchers have to record what they are going to study and what methods that will use. Burger thinks that such pre-registration of research is desperately needed in the field of psychology, because otherwise the temptation is to ‘graze’ for results in the data. ‘If you don’t determine in advance what exactly you are going to examine, you will always find things on which different research groups have different ideas. This increases the chance of coincidental findings. That is also where the crisis comes from,’ Burger explains the problems with the replication of psychological research. Because pre-registration of psychological research is a reaction to that, Burger thinks it is a shame that it is not yet common practice in psychology.

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