Opposite links of positive and negative symptomatology with memory errors in schizophrenia

We wished to confirm and extend a previous correlational study of our group, suggesting that positive symptoms in schizophrenia were linked to an increase in certain types of memory errors, and negative symptoms to a decrease in other types of errors. A post-hoc analysis was conducted in 33 schizophrenic patients and 40 normal control subjects on memory errors collected in a free recall task and two types of recognition tasks. The memory errors were intrusions and list errors in free recall, and decision bias towards false alarms in recognition, all assumed to reflect a source-monitoring failure. In a first analysis, the patient sample was split along the median for positive symptoms as rated by the Scale for the Assessment of Positive Symptoms (SAPS). In a second analysis, it was split along the median for negative symptoms as rated by the Scale for the Assessment of Negative Symptoms (SANS). Patients with high ratings of positive symptoms made more memory errors (intrusions, list errors, false alarms) than those with low ratings, supporting the hypothesis of a link between positive symptomatology and source-monitoring failure. On the other hand, patients with high ratings of negative symptoms made fewer of these errors than the other patients. Fewer errors were specifically associated with more affective flattening, alogia and anhedonia, whereas avolition was entirely unrelated to them.