“While large deficits in processing speed are already apparent at the first episode [of psychosis], deficits in verbal knowledge and memory continue to increase,” wrote Jolanta Zanelli, Ph.D., of King’s College London and colleagues. Understanding these differences can help guide cognitive remediation therapy in patients, the authors noted.
These findings were based on data collected as part of the Aetiology and Ethnicity in Schizophrenia and Other Psychoses (AESOP) study—a study that tracked changes in cognitive function in patients following a new diagnosis of psychosis. The study included 187 adults with first-episode psychosis or another psychotic disorder (for example, psychotic depression or persistent delusional disorder) who sought care in southeast London, Nottingham, or Bristol, and 177 healthy controls. All study participants were given a series of neuropsychological tests at enrollment and about 10 years later. Full 10-year data was available for 106 patients and 103 controls.
The baseline data showed that all patients with psychosis performed worse on tests measuring intellectual ability (IQ) as well as specific cognitive functions compared with controls, with patients with schizophrenia showing the greatest impairment. Approximately 10 years later, patients with schizophrenia showed worsening IQ, memory, and verbal skills compared with controls; their processing speed and visual-spatial memory did not decline. In contrast, patients with another psychotic disorder did not exhibit continued IQ decline compared with controls and only worsened in only certain memory functions.
Schizophrenia patients with severe symptoms at baseline showed greater cognitive decline over time than patients with mild or moderate symptoms; there was no evidence for an association between symptom severity and cognitive changes among patients with other psychoses. “While this subgroup was small (21% of the overall group), the magnitude of decline in the memory domain was large. Thus, this finding points to a potential subgroup of schizophrenia patients who may greatly benefit from being specifically targeted for cognitive remediation,” Zanelli and colleagues wrote.
To read more about this topic, see the Psychiatric News article “Could Cognitive Assessments Enhance Ability to Detect Transition to Psychosis?”