By Mark Cowen
Patients at high risk for psychosis show significant and widespread impairments in neurocognitive functioning and social cognition, results from a systematic review and meta-analysis of published studies show.
Furthermore, high-risk patients who later make the transition to full-blown psychosis show greater impairments in specific domains than those who do not, report Paolo Fusar-Poli (King's College London, UK) and colleagues.
They say the findings, published in the Archives of General Psychiatry, "may be useful in predicting psychosis and targeting early interventions."
The team searched the literature for studies published until 2011 that contained data on cognitive functioning in patients at high risk for psychosis.
In total, 19 studies, involving 1188 patients at high risk for psychosis and 1029 mentally healthy controls, met criteria for inclusion in the meta-analysis.
Examination of the pooled data revealed that high-risk patients had significantly poorer executive function, verbal fluency, attention, visual and verbal memory, and working memory compared with controls. The greatest differences between high-risk patients and controls were in the visual and verbal memory domains.
There was no significant difference between high-risk patients and controls regarding processing speed, however.
High-risk patients also showed significant impairments in social cognition compared with controls, as well as reduced general intelligence.
Among the high-risk patients, those who later made the transition to full-blown psychosis had significantly poorer baseline verbal fluency, verbal and visual memory, working memory, and general intelligence compared with those who did not. However, there was not enough data available to analyze social cognition in patients who made the transition to psychosis.
The researchers note that there was no evidence of publication bias, no significant heterogeneity across the included studies, and sensitivity analysis confirmed that the results were robust.
"This meta-analysis indicates that, despite comprising studies that varied in the method of subject ascertainment and the criteria used to define the high risk, there are consistent impairments in cognitive functioning in high-risk subjects as compared with matched controls," conclude Fusar-Poli et al.
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