By Mark Cowen, Senior MedWire Reporter
Patients with schizophrenia exhibit impairments in self-recognition, results from a systematic review and meta-analysis of published studies confirm.
Furthermore, the findings show that such impairments are more severe in schizophrenia patients with auditory hallucinations than in those without.
"The results suggest that self-recognition deficits must become an important treatment target in future studies," comment Flavie Waters (University of Western Australia, Perth) and team.
The researchers searched the literature for the period 1970-2010 for published studies that compared self-recognition between schizophrenia patients and mentally healthy individuals (controls), and between schizophrenia patients with and without auditory hallucinations, using a source memory task.
In total, 23 studies, involving 1370 participants, met criteria for inclusion in the schizophrenia versus control comparison, and nine studies, involving 315 participants, met criteria for the comparison of patients with and without auditory hallucinations.
In the schizophrenia versus control comparison, the groups were well matched for age (35.5 vs 35.4 years), although controls had a greater number of years of education compared with patients (16.4 vs 13.7 years) and a higher Intelligence Quotient (109.2 vs 102.1), the researchers note.
Meta-analysis of the pooled data from these 23 studies showed that schizophrenia patients had consistently poorer self-recognition accuracy than controls, with a moderate-to-large effect size.
In the comparison of patients with and without auditory hallucinations, the groups were well matched for age (34.0 versus 36.0 years), years of education (12.0 vs 11.0 years), age at onset (23.0 vs 22.4 years), and duration of illness (11.4 vs 13.7 years, although IQ was slightly lower in patients with than without hallucinations (100.0 vs 103.7).
Meta-analysis of the pooled data from these nine studies showed that patients with auditory hallucinations had significantly poorer self-recognition performance than those without hallucinations, with a moderate effect size.
Waters et al conclude in Schizophrenia Bulletin: "We found consistent evidence for impaired self-recognition in schizophrenia, which was most pronounced in patients with auditory hallucinations."
"This suggests an association, which may be causal in nature, between this deficit and auditory hallucinatory experiences in schizophrenia."
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