[Specificity and lack of specificity in psychiatric diseases]

The definition of a set of empirically accessible psychiatric variables on an international scale expresses the hope for nosologically more specific therapeutic methods. This is demonstrated by the example of the German translation of DSM III and by examples of biological markers for psychiatric syndromes. To begin with these are introduced as nosologically specific, but turned out to be nonspecific as a rule. Some examples of newest psychiatric research literature and results of our psychophysiological studies on endogenous psychoses and depressive syndromes show that a deeper understanding of the pathophysiological meaning of coherencies between psychopathological and pathophysiological basics is rendered more difficult by the fixation of the view of psychiatrists on nosological specificity. By means of some quotations from the works of Emil Kraepelin it is proved that already Kraepelin saw those complex conditions in regard to pathophysiological aspects and relativized his originally simple, causally determinated nosology. The interrelation between the physiological and the psychological level of effects is demonstrated by a simple example for the sedating effect of individual dosages of a compound on the healthy subject. While sedation turned out to be stable within subjects (same dosages given on different days) in the Electroencephalogram, it cannot be shown for the subjective and performance effects, measured with psychological tests. Statistical evidence of the psychological effect was only found across the whole group of subjects, because single subjects react on different days not in the expected way on the psychological level. That means, between the physiological and the psychological level there is no simple monocausal and linear relationship. We not only find an inhibited orienting response, indicated by the reduced skin conductance response, in depressive but also in schizophrenic patients. Schizophrenics with inhibited psychophysiological reactivity to environmental stimuli in the electrodermal system show depressive inhibition on the psychopathological level and withdrawal tendency. Schizophrenic and depressive patients show in the EEG a reduced expectancy wave (CNV) and a stronger post-imperative negativation (PINV) when they loose control over aversive imperative stimuli. Schizophrenic and depressive patients show an increased sensation threshold for warm stimuli, but not for cold stimuli, which means a lack of basic positive perceptions regarding temperature. These psychophysiological results with schizophrenic and depressive patients point at a fundamental dysregulation of psychophysical parameters in relation to the environment.(ABSTRACT TRUNCATED AT 400 WORDS)