[Prodromal symptoms of schizophrenia]

The concept of prodromal symptoms of schizophrenia has frequently been subject to debate. Authors widely admit the existence of early specific and non-specific signs preceding the first psychotic episode; however, they have yet to clearly demonstrate their ability to predict and specify the outbreak of a psychosis. These prodromal symptoms consist of behavioral abnormalities, pseudo-neurotic signs, subtle cognitive and affective changes. All these symptoms vary from patient to patient. In general, it is widely believed that future patients go through a variety of abnormal, subjective experiences that progressively develop during their pre-puberty and puberty periods. However, the limit of this assessment is that an individual could present the same prodromal symptoms without necessarily developing a psychotic illness, as a result of toxic intake, a situational crisis, etc. Furthermore, while the prodrome is a retrospective concept, its value and specificity can only be prospective, given that patients' descriptions of pre-morbid changes may be corrupted by inefficient memory reconstruction. DSM III-R included prodromal symptoms; individual presenting such symptoms would potentially present psychopathological vulnerability to psychosis regardless of associated genetic risk. Several investigations have shed doubts on their measurement's reliability; therefore, this classification is no longer present in the latest version (DSM IV). Moreover, recent neurodevelopemental hypothesis on schizophrenia have paved the way for possible early intervention, especially because early treatments could well improve illness prognosis. This viewpoint is reinforced by the improved tolerance of new anti-psychotic treatment. In this report, we review the key Articles published over the last 15 Years on this matter. We distinguish two schools of thought: on one hand, the German school referring to the validity of particular neuro-psychological symptoms: attention, perception, proprioperception which can be assessed with many evaluation tools: PAS, TDI, BSABS, SPI-A. The German school points to the fact that patients experimenting such changes could potentially be aware of their state. On the other hand, the Anglo-Saxon school refers to the detection of an "at risk" population. The Anglo-Saxons no longer refer to "prodromal symptoms" but rather to a "prodromal period" that extends to about one Year. This period would begin with the patient's first behavioral changes and extend until the first psychotic episode. Both schools agree that, at this stage, neither the recognition nor the description of the period preceding psychosis allows to effectively predict it. As a result, some Authors continue to refer to psychological changes forming a risk factor for the development of subsequent psychosis, rather than clear predictors of inevitable illness. As for relapses, prodromal signs and symptoms found in schizophrenic patients are both specific and non-specific. In most cases, patients experiment perceptions and behavioral changes before psychosis exacerbation. It is not uncommon for a substantial increase in prodromal symptoms to be followed by degradation in psychotic symptoms. On the other hand, many such increases in psychotic symptoms were not preceded by increases in possible prodromal symptoms; hence their importance in identifying the timing of an intervention, but many relapses will occur regardless of the detection of said symptoms.