Aims of the project
The aim of the project was to use brain imaging techniques and new classification techniques  to characterize differences in brain monoaminergic signaling, activation profile and anatomy, as well as genetic polymorphisms of timid (socially anxious / phobic) as compared to healthy control subjects. A particular focus has been on the re-uptake functions of serotonin and dopamine studied with positron emission tomography (PET). For this purpose, two PET ligands 11C-DASB and 11C-PE2I have been used for the serotonin and dopamine transporter proteins. In addition, magnetic resonance imaging (fMRI) has been conducted. The project was granted funding for three years and has essentially followed the project plan. The data collection has been completed and is now closed.

The project's main results
The project has generated a very large amount of data and comprehensive analyses are currently underway. Preliminary analyses/results exist, however. A subset of the research data collected has already been used and reported in a scientific report (Frick et al., 2015a). We there show that shy/phobic individuals have an increased availability of the serotonin transporter protein, as measured by the PET tracer 11C-DASB, which may be a compensatory effect on the re-uptake function because of enhanced synthesis of serotonin in these individuals (Frick et al., 2015a). Increased availability of the transporter was demonstrated in several anxiety-relevant brain areas including the putamen, caudate nucleus, insula, as well as the raphe- and amygdala nuclei. There was a correlation between symptom severity and serotonin transporter availability in the dorsal cingulate - a cortical region. These results, in turn, are consistent with animal data showing that anxious rats are hyperserotonergic and that serotonin may have an anxiety-inducing effect by affecting synaptic activity in the amygdala.

Preliminary analysis of a subset of the data on the dopamine transporter is also present. We have seen that the shy/socially phobic individuals have a higher binding potential and thus an increased availability of dopamine transporter compared with control subjects for example in the amygdala in the left hemisphere. There is also a positive correlation between symptom severity and transporter binding potential in several regions including hippocampus, amygdala and putamen. The results suggest that dopamine has an effect on socially anxious symptoms consistent what we have seen before with regard to serotonin transport. This will be presented at a world conference in Biological Psychiatry in Copenhagen, June 2017. The first scientific report on this will also be submitted in the summer of 2017.

The large amount of data collected in this project gives unique opportunities for multivariate analyzes, e.g. PET data can be related to functional and structural data obtained from MRI as well as  genetic variation. Support vector machine learning (SVM) will be used to evaluate the discriminatory power (discrimating between shy/nonshy) of the brain parameters collected. We will also examine the interaction between the serotonergic and dopaminergic reuptake measures that could be particulary important for discriminatory power, i.e to distinguish between shy/nonshy based on brain function. Analytical work and writing of scientific reports will likely continue for years to come.

As mentioned, the present study projects have studied neurochemical correlates of shyness/social anxiety focusing on the serotonin and dopamine transmitter systems. The neuropeptide substance P is also interesting , it primarily bind to the neurokinin-1 (NK1) receptor. Animal studies show that substance P release may induce anxiety while blockade of the NK1 receptor attenuates anxiety. We have with the PET tracer 11C-GR205171, in a recently published study showed that shy/phobic individuals have an increased availability of NK1 receptors in the amygdala, compared with control subjects (Frick et al., 2015b). Although this research question was not explicitly included in my application, I have reported financial support from Riksbankens Jubileumsfond here because the questions are strongly related (serotonin and substance P / NK1 systems interact) but also because the financial support enabled analysis and reports of existing data.

New research questions that have been generated in the project
The project has studied the transporter proteins of serotonin and dopamine. This, however, is only one piece of the puzzle and another important question is how the synthesis rather than re-uptake mechanisms of these two neurotransmitters interact. Dopamine synthesis can be measured with the PET tracer 11C-L-dopa, and serotonin synthesis with 11C-5HTP. Funding has been sought for such a follow-up study.

Another obvious question concerns the brain regions where we see deviations (PET, MRI) between shy and nonshy - are these regions also affected (normalized) by treatment with cognitive-behavioral therapy and/or serotonergic drugs. We also hope to this question in the future.

Another possibility is to link the results of our brain imaging and genotyping project (focusing on variation in the serotonergic and dopaminergic genes) with data from a public brain atlas of gene expression (Allen Human Brain Atlas).


The project's international presence
The project members are involved in an international research collaboration on social anxiety and brain structure / function - the so-called ENIGMA project. An article has recently been submitted for evaluation. Data on brain gray matter volume in social anxiety disorder collected by many international groups (including ours) have been pooled and analyzed in the ENIGMA collaboration. ENIGMA is further described at this URL:

http://enigma.ini.usc.edu/ongoing/enigma-anxiety/

Informative Research efforts outside the scientific community
The PI has, during the project period, participated several times in media coverage of our research. Both radio, television shows and newspapers show interest in our research on shyness and social phobia.
 
The project's two main publications

See the detailed description above.

Frick A, Åhs F, Engman J, Jonasson M, Alaie I, Björkstrand J, Frans Ö, Faria V, Linnman C, Appel L, Wahlstedt K, Lubberink M, Fredrikson M, Furmark T: Serotonin Synthesis and Reuptake in Social Anxiety Disorder: A Positron Emission Tomography Study. JAMA Psychiatry (2015a;72(8):794-802. doi:10.1001/jamapsychiatry.2015.0125

Frick A, Ahs F, Linnman C, Jonasson M, Appel L, Lubberink M, Långström B, Fredrikson M, Furmark T. Increased neurokinin-1 receptor availability in the amygdala in social anxiety disorder: a positron emission tomography study with [11C]GR205171. Translational Psychiatry (2015b) 5, e597; doi:10.1038/tp.2015.92


Project publishing strategy
The publications in the project will be peer-reviewed scientific articles with so-called Open Access. One example is the aforementioned article (Frick et al., 2015b) in Translational Psychiatry is an online magazine with open access and high quality. In other types of journals will still make articles or manuscript final version available in full text for all. For example, they are made available through the University's article database DIVA complying with the conditions for open access. Peer-reviewed conference papers will also be published.

List of publications and links to their own websites

Links
http://psyk.uu.se/forskning/forskargrupper/uppsala-affective-neuroscience-group/
http://katalog.uu.se/profile?id=N96-217_1

Publications
Frick A, Åhs F, Engman J, Jonasson M, Alaie I, Björkstrand J, Frans Ö, Faria V, Linnman C, Appel L, Wahlstedt K, Lubberink M, Fredrikson M, Furmark T: Serotonin Synthesis and Reuptake in Social Anxiety Disorder: A Positron Emission Tomography Study. JAMA Psychiatry (2015a;72(8):794-802. doi:10.1001/jamapsychiatry.2015.0125

Frick A, Ahs F, Linnman C, Jonasson M, Appel L, Lubberink M, Långström B, Fredrikson M, Furmark T. Increased neurokinin-1 receptor availability in the amygdala in social anxiety disorder: a positron emission tomography study with [11C]GR205171. Translational Psychiatry (2015b) 5, e597; doi:10.1038/tp.2015.92