In previous studies, we demonstrated that
tandospirone, a serotonin-5-HT1A partial agonist, added to ongoing treatment with small to moderate doses of typical
antipsychotic drugs, improved executive function and verbal learning and memory. However,
tandospirone is not available in most countries, and atypical
antipsychotic drugs (AAPDs) have largely replaced typical
antipsychotic drugs as the primary treatment for
schizophrenia. Therefore, the goal of this randomly assigned placebo-controlled double-blind study was to determine if the addition of
buspirone, a widely available 5-HT1A partial agonist, would enhance cognitive function, in subjects with
schizophrenia treated with AAPDs. Seventy-three patients with
schizophrenia, who had been treated with an AAPD for at least three months, were randomly assigned to receive either
buspirone, 30 mg/day, or matching placebo. All other medications remained unchanged. Attention, verbal fluency, verbal learning and memory, verbal working memory, and executive function, as well as psychopathology, were assessed at baseline, and 6 weeks, and 3 and 6 months after baseline. A significant Time x Group interaction effect was noted on the Digit Symbol Substitution Test, a measure of attention/speeded motor performance, due to better performance of the
buspirone group compared to the placebo group at 3 months. No significant interaction effects were noted for other domains of cognition. Scores on the Brief Psychiatric Rating Scale (Total, Positive) were improved during treatment with
buspirone but not placebo, but the effects did not reach statistical significance. The results of this study showed a possible benefit of
buspirone augmentation of AAPDs to enhance attention. However, we did not replicate the results of the previous study with
tandospirone, which may be due to the differences between
tandospirone and
buspirone, between typical
antipsychotics and AAPDs, or a combination of the above. Further study to determine the usefulness of
5-HT1A agonist treatment in
schizophrenia is indicated.