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Brain changes underlying social anxiety: numbers count!

In een mega-analyse scheppen Leidse onderzoekers helderheid in tegenstrijdige resultaten van onderzoek naar sociale angststoornis. Hun internationale studie laat zien dat het voor betrouwbare onderzoeksresultaten van belang is om zo groot mogelijke onderzoeksgroepen te bekijken. Publicatie in NeuroImage:Clinical.

In a recent mega-analysis, researchers from Leiden University aimed to clarify the contradictory findings of research into social anxiety disorder. They found that to obtain reliable research results having the largest possible sample size is important.

The social anxious brain

Because patients with a social anxiety disorder are extremely afraid of negative evaluation by others, they avoid social situations wherever possible. This has a huge impact on their lives. But what changes in the brain underlie this extreme fear? A lot remains unclear.

Earlier studies of abnormalities in brain structure have come up with contradictory results. This prompted Janna Marie Bas-Hoogendam and Henk van Steenbergen of Leiden University, together with Nic van der Wee of the Leiden University Medical Center, to set up an international collaborative project to collect and analyse a large number of MRI-scans from patients with social anxiety disorder. 

The scans originate from five countries: the Netherlands, Germany, Sweden, South Africa, and the U.S. The database includes brain scans from a total of 174 patients with social anxiety disorder and 214 healthy controls, making it the largest sample of social anxiety disorder patients ever investigated. The results of this mega-analysis have been published in the journal NeuroImage:Clinical.

Incoming social signals in the brain of individuals with social anxiety

Bas-Hoogendam explains: 'In the mega-analysis we compared the volume of gray matter in the brains of patients with that of healthy controls. The results showed that social anxiety patients have more grey matter in a deeper part of the brain, the areas known as the basal ganglia. This change was related to the severity of symptoms that patients reported: patients who indicated that they suffered the most from their social anxiety showed the greatest changes in this structure in comparison with the healthy controls. It is possible that this change in structure has something to do with the way the brains of socially anxious individuals process incoming social signals, but to establish this we need further research, for instance using functional MRI scans.'

False positives

Van Steenbergen adds: 'Surprisingly enough, we did not find any structural changes in a number of brain areas that were identified in other studies. We think the reason for this is that the earlier studies each examined relatively small groups of patients. This can lead to false positive results, which are difficult to replicate. Variability in research methods and differences between groups of patients can also contribute to such contradictions.'

The largest possible research sample

According to the researchers, the study demonstrates that to ensure reliable results, it is important to have the largest possible research sample. With this in mind, they are already busy with plans for a new project. Bas-Hoogendam: 'We’re continuing our research into brain changes in social anxiety disorder in the context of the ENIGMA project. ENIGMA stands for ‘Enhancing Neuro Imaging Genetics through Meta-Analysis'.'

Interested in the ENIGMA-ANXIETY working group? Watch the video’s on YouTube!

 

100 researchers all over the world

'The aim of the project is to obtain greater insight into the structure and function of the brain, both in healthy individuals and in patients with a brain disorder. Within ENIGMA we’ve set up a working group that focuses on anxiety disorders. We are delighted that over 100 researchers from all over the world have signed up to take part in the project. The analysis will start shortly, and we hope that this will afford us more insight into the brain changes that underlie extreme anxiety.'

See publication in NeuroImage:Clinical