By Mark Cowen, Senior medwireNews Reporter
Antipsychotic-naïve patients with a first-episode of schizophrenia show deficits in all cognitive domains compared with mentally healthy individuals, researchers report.
R Andersen (Copenhagen University Hospital, Denmark) and team also found that most of these cognitive deficits in first-episode patients could be accounted for by impaired processing speed.
"The results support the contention of a global cognitive dysfunction in schizophrenia that to some extent may be determined by impaired processing speed," write the authors in European Psychiatry.
The team studied 48 antipsychotic-naïve patients (35 men) with first-episode schizophrenia who were aged a mean of 25 years, and 48 mentally healthy individuals matched for age, gender, and parental socioeconomic status.
The cognitive domains of verbal intelligence, processing speed, sustained attention, working memory, reasoning and problem solving, verbal learning and memory, visual learning and memory, and reaction time were assessed using a comprehensive battery of 17 tests. An additional domain of global cognition was derived from the summary of all cognitive domains.
The team found that first-episode schizophrenia patients had significantly poorer performance in all cognitive domains, including global cognition, than controls.
Analysis of processing speed as a covariate accounted for the significant differences between patients and controls in all cognitive domains, except for verbal intelligence and global cognition, which approached nonsignificance.
The researchers note that, in schizophrenia patients, there were significant correlations between all domain measures, except for the verbal learning and memory domains, which did not significantly correlate with sustained attention, reaction time, and visual learning and memory.
"First-episode, antipsychotic-naïve patients with schizophrenia show deficits in all the cognitive tasks and domains that were assessed, when compared to healthy controls," the researchers summarize.
They conclude: "The results of this study sharpen the hypothesis of slowed information processing as a central feature of cognitive impairment in schizophrenia, also at a stage of the illness when test performance has not been influenced by potential medication or chronicity confounders."
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