What is the evidence for changes in cognition and functioning over the lifespan in patients with schizophrenia?

Cognitive deficits in schizophrenia are important predictors of impairment in most functional domains and are a critical therapeutic target. These deficits appear at or before the onset of illness, are stable across time in most patients, and can be improved by cognitive remediation treatments. Recent evidence, however, suggests that cognitive function does not necessarily follow a pattern of age-related decline. Several studies evaluated this pattern of decline in schizophrenia patients compared to both natural aging and degenerative conditions such as Alzheimer's disease. Age-related differences were not comparable to either normal aging or Alzheimer's disease. Older patients with an extensive history of illness and protracted institutionalization have shown a greater progressive decline. These deficits were also observed in older patients who were no longer institutionalized, with these patients demonstrating decline in functional capacity across time compared to healthy controls and patients with no lengthy institutional stay. There were 2 clear conclusions from this body of data. First, there appear to be 2 separate periods of deterioration in schizophrenia patients. These patients appear to decline the most at 2 key time points; the first occurs some time prior to the first psychotic episode and the second begins at approximately 65 years of age. The second important conclusion is that these 2 important periods of time may be the time point at which an aggressive intervention may have the greatest impact.