Schizophrenia Research Trends

148A. Orosz, K. Cattapan-Ludewig, G. Gal and J. Feldonif they differed in their salience. A stimulus which is more salient than the other is easierconditioned (21). Hence, there is faster learning on salient stimuli.The new visual LI paradigms introduced above both apply a within-subject design but donot encounter such problems because the task is quite complex - there are several PE- as wellas NPE-CS which even change roles within a test session (60;71;74).DISRUPTED LI AS A MARKER OF SCHIZOPHRENIAComparable to animals, intoxication with amphetamine elicits psychosis like symptoms(75) and disrupts LI (18;76-79) in healthy human individuals. Additionally, amphetaminealso exacerbates psychosis in schizophrenia patients in remission (80). As acuteschizophrenia is thought to be primarily due to a current hyperdopaminergic state (20), LI isexpected to be absent in acute schizophrenia patients. Actually, there are many studiessupporting the notion that LI is disrupted in acute schizophrenics (9;20;73;81;82) while it isrobustly present in healthy subjects (76;78). However, there are also findings reportingnormal (13;64;65;83) or potentiated (84) LI in schizophrenia.Concerning antipsychotic drugs, it is assumed that they enhance LI in healthy controls(85). Inconsistently, Williams and colleagues reported that the typical APD haloperidolabolished auditory LI in healthy volunteers (65). This group also found disrupted LI inmedicated acute schizophrenics. This result had already been found by Baruch et al. (20)before.LI is disrupted in acute, but not in chronic schizophreniaIn chronic schizophrenia patients constantly medicated with APDs, LI is suggested to bereinstated (20;58;81). Baruch et al. (20) considered that the difference between acute andchronic schizophrenia is a result of distinct situations of antipsychotic medication. It wasshown that LI is also intact in unmedicated and still symptomatic chronic schizophreniapatients (73). It was suggested that illness duration rather than neuroleptic medication isresponsible for LI normalization in chronic schizophrenia (73). Support for this is providedby Rascle and collaborators (81) who found enhanced LI in chronic schizophrenia patients.Moreover, they report that the LI effect did not depend on the drug treatment status (drugfree,atypical or typical neuroleptics). Based on these findings, LI disruption might be treatedas a state rather than a trait marker of acute schizophrenia (18). Cohen and co-workers (84)suggest that LI stabilization might be correlated with the composition of symptom types. Inacute schizophrenia positive symptoms are more prevalent than in chronic schizophrenia.These are attributed to the currently increased DA level (86) which is also responsible for LIdisruption. Therefore, the shift of symptomatology away from positive symptoms towardsnegative symptoms may lead to LI reinstatement in chronic schizophrenia.It should, however, be pointed out that there are also data showing disrupted LI inchronic schizophrenia regardless of medication or illness duration (83).