[Anxiety and depression - the role of blood-brain barrier integrity]

Among mental illnesses, anxiety disorders represent the second most frequent disorder. According to WHO Survey 2017, 264 million people suffer from their different types globally. The emergence of anxiety disorders can often increase the likelihood of developing other psychiatric illnesses such as depression, which is the most common mental illness with 300 million people affected worldwide. Although the two diseases mentioned above are widespread throughout the world, the exact physiological causes of their development and the way they are connected are not well understood. However, in order to be able to use right treatment it would be important to know the physiological background in their development. The use of anxiolytics and antidepressants is not always effective and safe, which may be due to the subtypes of these mental disorders with different etiologies. Identifying the right therapeutic strategies could be also challenging because of the phenotypic overlap between anxiety disorders and depression. Their comorbidity has been confirmed by many studies, but their exact physiological relationship is still unclear. Previous studies suggested that blood-brain barrier proteins play an important role in the development of depression and anxiety disorders and might partially explain their comorbidities. In our summary we review the current literature related to this topic.