Memory impairment has been acknowledged as a core cognitive deficit in schizophrenia, and it is present irrespective of specific features related to the patient or the evolution of the disorder. It is suggested that distinct functional subsystems of memory are differently impaired in these patients, hence the broad range of levels of functioning affected in this specific population. The aim of this study was to assess working memory performance in multiple episode schizophrenia patients. A group of patients diagnosed with schizophrenia and a control group of healthy subjects were comparatively evaluated with 3 neurocognitive tests which require the use of working memory subsystems. Our results indicate significantly poorer performance in the case of patients suffering from schizophrenia, in all three working memory tests – they displayed impaired face recognition abilities and used a significantly higher number of non-list words when asked to repeat a list of words, which may be particularly relevant for their social functioning. The neurobiological and genetic background of the memory impairment in schizophrenia have been acknowledged due to increasing body of evidence, and the current study supports the current data which state that working memory deficits in schizophrenia are consistent, stable and comprehensive. This is particularly relevant for the personal management, and also for the academic, interpersonal and social rehabilitation of schizophrenia patients.
Background: Working memory deficits are considered endophenotypes for schizophrenia. Therefore, they are present in ill subjects prior to the onset of the disorder, during the evolution of the disorder as well as in healthy relatives.
Aims: The purpose of this study was to examine the working memory of first episode schizophrenia patients (FEP) and their healthy siblings. In addition, we examined the relationship between the duration of untreated psychosis (DUP), the global functioning, symptoms, and cognitive function in first episode patients.
Methods: 49 first episode inpatients, 25 healthy siblings and 41 healthy volunteers were recruited. Patients were diagnosed using the SCID for DSM-IV disorders, assessed with the PANSS and Global Assessment of Functioning scale (GAF). DUP was calculated by means of multiple-source interviews, with patients and relatives. The Rey Auditory Verbal Test (RAVT), the Paired Associates Learning Test (PAL), the Spatial Span Test (SSP) and the Spatial Working Memory Test (SWM) from the CANTAB were administrated to all subjects.
Results: Patients had an average duration of untreated psychosis of 303.10 days. The overall performance of first episode schizophrenia patients was significantly lower compared to healthy individuals on all cognitive tasks, with the exception of the errors on the SSP. Healthy siblings had intermediate scores; they performed similar to controls on some tasks (RAVLT – retroactive inference, delayed recall, recognition, PAL first trial score and on the number of completed stages), and lower on others (RAVLT – immediate memory, total learning, proactive inference, PAL total errors and the stages completed on the first trial).
Discussion and conclusions: A significant correlation between the DUP and the PANSS general symptoms scores and low general function could be established. However, there were no significant correlations between DUP and cognitive tasks.