Often anxiety is based upon real or imagined threats and followed by insufficient coping strategies. Some anxiety states are exclusively caused by organic brain diseases, especially by primary tumours of the mesiotemporal lobe. The type of anxiety-disorders depends on the underlying psychodynamic and neurobiological mechanisms. Posttraumatic stress disorder may be regarded as a paradigm, how extraordinary stressful events build up an "engramme of molecular anxiety". Chronification of anxiety states as well as problems in treatment could be understood using this paradigm.