Negative symptoms are considered the most debilitating and refractory aspect of
schizophrenia, being associated with poor social, occupational and global outcomes. Conventional
antipsychotics have limited efficacy against these symptoms and poor tolerability profiles. Atypical
antipsychotics are an alternative treatment, and this 12-week, randomised, flexibly dosed study compared the efficacy, safety and tolerability of
quetiapine and
olanzapine in this regard. Of the 40 patients who entered the study (32 male; 8 female), 19 were randomised to
quetiapine (mean dose 637 mg/day, mean
treatment duration 80 days) and 21 to
olanzapine (mean dose 16 mg/day, mean
treatment duration 78 days).
Quetiapine and
olanzapine were similarly effective: in each treatment group significant improvements at Week 12 were observed for negative symptom scores on the SANS and the PANSS, and for subscale scores of affective flattening and
alogia on the SANS. Both treatments were well tolerated in this patient population, with no worsening of extrapyramidal symptoms in either case. Anxiety and
insomnia were the most common adverse events (> or =7% of patients in each group), but were not
drug-related. Although this is a small study with limited power, the results support the effectiveness of
quetiapine and
olanzapine in treating the negative symptoms of
schizophrenia.