The onset and time course of response of negative symptoms to add-on fluvoxamine treatment.

Not enough is known about the propensity of individual negative symptoms to respond to treatment and the dynamics of this change. We have previously shown that adding the selective serotonin reuptake inhibitor fluvoxamine to antipsychotics can improve negative symptoms, and now provide data on the response of individual negative symptoms to such treatment. We examined items on the Schedule for the Assessment of Negative Symptoms for patients participating in two published controlled studies comparing the effect of add-on fluvoxamine and placebo on negative symptoms. Using a mixed regression model, we analysed item scores at each week of the study to identify the first signs of a treatment effect. Potential confounding effects of depressive extrapyramidal and positive symptoms were statistically controlled. Eleven of 16 items tested showed improvement, five within 2 weeks and a further four within 3 weeks of starting treatment. The most rapidly responding items included core negative symptoms such as alogia. The propensity for and rate of improvement with fluvoxamine treatment differs for the various negative symptoms. Many symptoms, including those generally agreed to be core features of the illness such as alogia, improved within 2-3 weeks of treatment initiation.