Neurocognition, negative symptom effects in psychotic prodrome clarified

By Lucy Piper, Senior medwireNews Reporter

The contribution of neurocognition and negative symptoms to impaired social and role functioning in patients at clinical high risk (CHR) of psychosis is important enough to warrant targeting both with therapeutic interventions, say researchers.

Findings from the first phase of the North American Prodrome Longitudinal Study “support the rationale for integrative psychosocial rehabilitation programs for early psychosis that target both negative symptoms and neurocognition as a means of improving functioning,” say researcher Larry Seidman (Commonwealth Research Center, Boston, Massachusetts, USA) and colleagues.

In all, 167 individuals at CHR of psychosis participated in the study, 96 of whom were reassessed at 12 months.

Regression analyses showed that negative symptoms, measured using the Structured Interview for Prodromal Symptoms, were significantly and independently associated with social and role functioning (assessed with the Global Function scales) at baseline and 12-month follow-up. Neither positive nor disorganized symptoms accounted for unique variance in functioning at either time point.

The researchers also found that composite neurocognition, based on the mean score of a battery of neurocognitive tests including verbal comprehension, processing speed and executive functioning, contributed uniquely to social and role functioning at baseline after taking into account negative symptoms. The significant, independent association remained for role, but not social, functioning at the 12-month assessment.

Seidman et al report in Schizophrenia Bulletin that negative symptoms were the strongest predictor of social and role functioning at baseline and 12 months, having a small-to-medium effect. Composite neurocognition had a small independent effect on social and role functioning at both time points that was stronger for role than social functioning. In both cases, negative symptoms mediated the relationship with composite neurocognition.

Of all the neurocognitive tests assessed, IQ estimate, Digit Symbol/Coding and verbal memory selectively accounted for social and role functioning at baseline and follow-up after accounting for symptoms.

The researchers note that the overlap among neurocognition, negative symptoms and functioning was only modest. Removing the two negative symptoms – social anhedonia or withdrawal and deterioration – from analyses substantially reduced the relationship between negative symptoms and functioning but strengthened the relationship between composite neurocognition and functioning.

Despite this modest overlap, the researchers say that neurocognition, social and role functioning and negative symptoms are “sufficiently independent to warrant inclusion in multivariate prediction models”.

They conclude that the generation of specific treatments designed to improve neurocognition and negative symptoms could improve the lives of CHR individuals.

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