In the present review, we deliver an overview of the involvement of metabotropic glutamate receptor 5 (mGluR5) activity and density in pathological anxiety, mood disorders and addiction. Specifically, we will describe mGluR5 studies in humans that employed Positron Emission Tomography (PET) and combined the findings with preclinical animal research. This combined view of different methodological approaches—from basic neurobiological approaches to human studies—might give a more comprehensive and clinically relevant view of mGluR5 function in mental health than the view on preclinical data alone. We will also review the current research data on mGluR5 along the Research Domain Criteria (RDoC). Firstly, we found evidence of abnormal glutamate activity related to the positive and negative valence systems, which would suggest that antagonistic mGluR5 intervention has prominent anti-addictive, anti-depressive and anxiolytic effects. Secondly, there is evidence that mGluR5 plays an important role in systems for social functioning and the response to social stress. Finally, mGluR5's important role in sleep homeostasis suggests that this glutamate receptor may play an important role in RDoC's arousal and modulatory systems domain. Glutamate was previously mostly investigated in non-human studies, however initial human clinical PET research now also supports the hypothesis that, by mediating brain excitability, neuroplasticity and social cognition, abnormal metabotropic glutamate activity might predispose individuals to a broad range of psychiatric problems.

HighlightsThe involvement of noradrenaline in moral and social judgments is reviewed.Noradrenergic transmission is causally involved in implicit racial biases, racial face perception, as well as increasing social harm aversion.Fear and anger – mediated by limbic circuit brain activation – might mediate moral and social decisions and acts.

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The objective of this study is to examine the potential impact of using the internet on medical consultations by analysing the attitudes, attributions, and emotional responses of parents who have been informed by specialists that their child does not have attention-deficit hyperactivity disorder (ADHD) and to examine the nature of the feedback they obtained from members of online internet support groups. Over 40,000 messages from the five most popular international internet forums discussing children with ADHD were analysed. Messages from parents who reported that they had seen at least one specialist (e.g. paediatrician, psychiatrist or psychologist) because of their concerns that their child had ADHD were identified. The children included boys and girls with an age range from 2 to 16 years. Of these, we analysed messages where the parents additionally reported that the specialist had excluded a diagnosis of ADHD. Using these criteria, 91 messages from parents who had consulted over 200 different specialists and 398 replies to these messages were identified for content analysis. The replies to concerned parents were analysed to determine whether they were offered impartial advice. A majority of the parents reported that they did not believe the specialist and were unhappy about their child not being diagnosed with ADHD. They expressed dissatisfaction with the professional's opinions and the implication that their child's conduct was caused by their poor parenting skills. Importantly, 87.6 % of the responses that these parents received, from other members of online forums, reinforced the parent's negative attitude towards the professional's judgement. It was generally suggested that the parents should not believe the expert and should seek a further opinion. The use of the internet may encourage "doctor shopping" and mistrust in health services. Medical professionals and others may need to be aware of this, and parents may need more support than is generally offered to be able to accept alternative explanations for their child's behaviour.