By Eleanor McDermid, Senior medwireNews Reporter
Remission of positive and negative symptoms is the most important predictor of functional outcomes among patients with first-episode psychosis, with cognition having only a small impact, say researchers.
Ashok Malla (McGill University, Montreal, Quebec, Canada) and team found that the length of remission of negative symptoms had the largest effect on functional outcomes 1 year after psychosis onset. However, remission of positive symptoms had a prominent effect on 2-year outcomes, which they say illustrates “the importance of achieving lengthy remissions of both positive and negative symptoms.”
The researchers assessed 208 patients for functional outcomes on the Strauss Carpenter Scale 1 year after first-episode psychosis, at which point 30.0% had been in total symptom remission for an average of 2.4 months. Of 159 assessed after 2 years, 41.5% had been in total remission for an average of 5.7 months.
A model that included age, medication compliance, duration of untreated psychosis, substance abuse and premorbid adjustment accounted for only a very small proportion of the variance in functional outcomes at either 1 or 2 years. Adding verbal memory, measured on the Wechsler Memory Scale-III after treatment initiation when the patients were considered stable, increased the proportion of variance explained, but only to about 9% in both cases.
By contrast, adding the length of total remission increased the variance explained to 30% for 1-year outcomes and 29% for 2-year outcomes.
Negative symptoms made the largest contribution to 1-year outcomes; a baseline model including length of remission of positive symptoms explained 15% of the variance in functional outcomes, but adding negative symptom remission explained an additional 20%.
Remission of negative symptoms was difficult to achieve at both time points, with 33.2% and 48.4% of patients achieving this at 1 and 2 years, respectively, compared with 67.8% and 69.2% who achieved remission from positive symptoms.
However, positive symptoms had a more substantial effect on 2-year outcomes; together with other baseline variables, length of positive symptom remission explained 24% of the variance in functioning, while adding remission of negative symptoms explained an additional 13% of the variance.
“The difficulties associated with achieving complete remission underline the importance of searching for effective treatment of persistent positive and, especially, negative symptoms”, writes the team in the Journal of Clinical Psychiatry.
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