La schizophrénie tardive est-elle secondaire à des processus neurodégénératifs? Une revue de la littérature

It is notable that the studies conducted do not differentiate between LOS and VLOSP, since these two groups of patients are generally mixed. Furthermore, an attempt to analyse the data has to take into account only the studies which have included subjects with strict criteria of schizophrenia, independently of the disorders' age of onset. In addition, we found no study comparing LOS and Lewy Bodies Dementia, which is however an important differential diagnosis. The two main hypotheses tested appear to be: (1): is LOS a prodrome of AD? (2): is LOS consecutive to CD? This review permits a partial answer to these questions. First, LOS as a prodrome of AD seems very unlikely, considering anatomopathological studies. However, it is possible that subjects with later age of onset of the disease develop dementia at 10 years. Second, CD seems not to be altered by the cerebral tracts which are implicated in EOS. A hypothesis could be that the tracts implicated in LOS and EOS differ. This might explain the differences found in clinical (less formal thought disorders and negative symptoms in LOS compared with EOS) and electroencephalographical studies (no reduction of P300's amplitude in LOS, which has however been proposed as trait marker of schizophrenia in EOS) between LOS and EOS. These tracts could be related to a limbic tauopathy found in anatomopathological studies. More vulnerable subjects would develop LOS with ageing. Other subjects would develop LOS secondary to CD. This could explain the later age of onset of the disease in these subjects.