Cognitive function and suicide risk in Han Chinese inpatients with schizophrenia.

The lifetime risk of suicide in patients with schizophrenia is estimated to be 4.9-13%. While there are many known risk factors for suicide in schizophrenia, the relationship between cognitive function and suicide risk is unclear, particularly in non-Caucasian populations. In our cross-sectional study, we administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to 316 Han Chinese chronic inpatients with schizophrenia and compared the performance of those who had attempted suicide (n=25) to non-attempters (n=291). The lifetime suicide attempt data were collected from medical records and interviews with patients and their family members. We found a lifetime suicide attempt rate of 7.9%. Suicide attempters were more likely to be single, but showed no significant differences in other demographic factors such as age, gender, or living arrangements. Contrary to our hypothesis, there was no significant relationship between performance on the RBANS test and lifetime risk of suicide attempts in Han Chinese inpatients with schizophrenia. The literature remains mixed on this topic. Culturally influenced differences in suicidal behavior may have affected the outcome of this study and further investigation of this topic is necessary.

Cognitive function, plasma MnSOD activity, and MnSOD Ala-9Val polymorphism in patients with schizophrenia and normal controls.

Excessive reactive oxygen species are thought to produce oxidative damage that underlies neurodegeneration and cognitive impairment in several disorders including schizophrenia. The functional Ala-9Val polymorphism of the mitochondrial enzyme manganese superoxide dismutase (MnSOD), which detoxifies superoxide radicals to hydrogen peroxide, has been associated with schizophrenia. However, no study has reported its role in cognitive deficits of schizophrenia as mediated through MnSOD activity. We recruited 923 schizophrenic inpatients and 566 healthy controls and compared them on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), plasma MnSOD activity, and the MnSOD Ala-9Val polymorphism. We assessed patient psychopathology using the Positive and Negative Syndrome Scale. We showed that the MnSOD Ala-9Val polymorphism may not contribute directly to the susceptibility to schizophrenia. The Ala variant was associated with worse attention performance among chronic schizophrenic patients but not among normal controls. Plasma MnSOD activity was significantly decreased in patients compared with that in normal controls. Moreover, MnSOD activity among the schizophrenic Ala allele carriers was correlated with the degree of cognitive impairments, especially attention and RBANS total score. We demonstrated an association between the MnSOD Ala-9Val variant and poor attention in schizophrenia. The association between higher MnSOD activity and cognitive impairment in schizophrenia is dependent on the MnSOD Ala-9Val polymorphism.