[Concepts of vulnerability of psychiatric diseases].

Despite intensive research in recent decades, the search for the aetiopathogenesis of psychiatric diseases is just as relevant as ever. In recent years, ideas of the aetiopathogenesis of psychotic diseases based on the concept of "vulnerability" in its diverse variations and developments have been gained increasingly ground. The publications of Zubin and associates above all have contributed to a "vulnerability model". According to this descriptive model, schizophrenic disturbances develop as a result of stimuli/irritants or stress factors under modulation of the social and physical environment as well as dependent on the premorbid personality. The increased vulnerability which gives rise to this is perceived as a threshold descensus of the individual towards stimuli/irritants (with a deficit counter--irritants impulses). Apart from that, multi-causality of vulnerability is assumed as the starting point, whereby there is the possibility of several therapy approaches. Moreover, contrary to the prevailing pessimistic view that schizophrenia is a process-type progressive disease, an episodic nature of schizophrenic psychoses is postulated with a prognosis that is indeed positive in the long term. In recent years, although often not explicitly stated, Zubin's concept of vulnerability was also indubitably subjected to various further developments (the vulnerability stress model by Nuechterlein and associates as also the integrative psycho-biological schizophrenia model by Ciompi may serve as examples). Worth mentioning are also various new concepts from system sciences (such as those from cybernetics, synergetics, the chaos theory, the communication theory, structure determinism etc.), which endeavour to clarify the problem of psychosis. The evaluation of central neurophysiological function deviations with schizophrenics and their relations has so far been oriented above all towards the vulnerability model of Zubin and Nuechterlein, which differentiates temporarily relatively stable trait markers with generally unaltered expressivity at the pre-, intra-, and post-psychotic stages as well as episode markers and intermediate markers. However, specific factors contributing to the pathogenesis of schizophrenic disturbances have not as yet been found, in addition, there is still a multitude of methodological problems and distinctive features to fulfill the expectation of a comprehensive concept with which the whole complexity of the occurrence, the progress, and the outcome of psychoses can be explained. Reintroduction of the concept of vulnerability experienced, as Schmidt-Degenhardt put it, "a renaissance in use that appeared almost inflationary and a completely dubious popularisation ... without reference to its historical implications...". Consequently, a critical view of the use of this term would appear to be necessary.