Cognitive functioning in schizophrenia: a lifespan perspective

Cognitive disorders are now well known in schizophrenia, but their evolution over time and particularly during aging remains poorly described. Current evidence indicates that cognitive deficits including attention, working memory, verbal learning and memory, and executive functions are present in 80% of individuals with schizophrenia, which, on average, are around two standard deviations below that in healthy controls. Cognitive impairments are important predictors of functioning in daily life, including quality of life, inability to live independently and unemployment. From a lifespan perspective, they are evident in infancy (18 months) and continually increase between infancy and adulthood (20 years) in full-scale IQ and most of cognitive domains, accelerating during the prodromal phase. Cognitive deficits are significant predictor of the psychotic transition, and they stabilize after the first psychotic episode until the age of fifty suggesting that cognitive deficits are mainly established before the prodromal phases of psychosis. Time course of cognitive impairments in elderly patients with schizophrenia appears to be more heterogeneous. While the data suggest that they are stable with advancing age, a subgroup of institutionalized older patients stands out for a significant cognitive decline, without it being possible to determine the causal direction of this association. The twofold increased risk of developing neurodegenerative dementia in this population, combined with institutionalization, could partly explain this cognitive decline in some patients. Long-term longitudinal studies in older adults with schizophrenia are clearly needed, particularly in France. Protective factors such as recovery-focused and psychosocial approaches need to be studied in this population, which has a 15-year shorter life expectancy than the general population.