Executive functions in schizophrenia aging: differential effects of age within specific executive functions

Cognitive deficits are considered to be one of the core features of schizophrenia, but their course in late-life schizophrenia is still controversial. Specifically, it remains unclear whether schizophrenia patients show accelerated aging despite the importance of this question for cognitive remediation. Moreover, although the diversity of executive functions is well established, most studies continue to use general, unspecific tests. The aim of this study was to determine how each of the four specific executive functions (shifting, updating, inhibition and access to long-term memory) described in Miyake et al. (2000) and Fisk and Sharp (2004) is affected by aging in schizophrenia compared to healthy aging. 20 younger (age 18-34), 17 middle-aged (age 35-49) and 25 older (age 59-76) schizophrenia patients and 62 healthy comparison subjects matched for gender, age and education performed a neurocognitive battery evaluating the four specific executive functions. Results showed that schizophrenia patients performed worse than comparison subjects on shifting, updating and access, whereas inhibition seemed preserved. Age affected the four functions with increased degradation of shifting and access in schizophrenia patients, whereas updating and inhibition showed a normal decline with age. As age affected the specific executive functions differently, remediation programs should be adapted to older patients by targeting shifting abilities and strategic access to memory. Our results also stress the need to assess executive functioning accurately before admitting patients to remediation programs. Models of specific executive functions are very interesting for understanding the complexity of cognition in schizophrenia and its course during later life so that healthcare can be adapted accordingly.