Cognitive impairment predates psychosis onset

By Eleanor McDermid, Senior medwireNews Reporter

People at clinical or familial risk for schizophrenia have similar cognitive deficits to those in patients with first-episode schizophrenia, a study shows.

At-risk individuals and those with first-episode schizophrenia had impaired performance across a range of neurocognitive tests relative to mentally healthy controls, report Alp Üçok (Istanbul Faculty of Medicine, Turkey) and co-workers.

The impaired performed on individual tests translated to significantly worse composite scores for memory/learning, executive function, and attention, as well as global cognition. The only exception was that the memory/learning score was not significantly worse in people at familial high risk than in controls.

But there were also differences between the patient and at-risk groups, with the 53 first-episode schizophrenia patients having significantly worse sustained attention than 30 of their siblings (ie, people at familial risk). They also had poorer scores for working memory and attention than 52 patients meeting the clinical criteria for ultra-high risk, and had a significantly lower composite global cognitive score, at –0.32 versus –0.04, compared with +0.64 in controls.

Cognitive performance in the first-episode schizophrenia patients was unrelated to the duration of untreated psychosis.

The difference in cognitive scores between the patients and at-risk groups therefore implies “that cognitive deficits gradually increase in progressive stages and supports the staging model of psychosis,” write Üçok et al in Schizophrenia Research.

“On the other hand, the lack of significant differences between risk groups and those with [first-episode schizophrenia] in some domains supported the hypothesis that cognitive functions reflect an endophenotype that is already present in prodromal stages of the illness,” they add.

There were no differences in individual test results or in composite cognitive domain scores between the two at-risk groups.

“Our aim as a next step is to detect cognitive predictors of transition to psychosis in both groups in a study with a longitudinal design and with larger sample size,” say the researchers.

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