The effect of long-acting risperidone on working memory in schizophrenia: a functional magnetic resonance imaging study.

Cognitive abnormalities represent an important therapeutic target in the treatment of schizophrenia. Working memory deficits are among the core abnormalities and affect social functioning. We used functional magnetic resonance imaging to examine cortical systems supporting working memory in patients with schizophrenia treated with risperidone long-acting injections (RLAIs) versus those on conventional depot medication (CONV). Sixteen patients on RLAI, 16 patients on CONV matched for clinical symptoms and other illness variables, and 8 HCs performed an n-back task (1-, 2-, 3-back) in the scanner. The level of performance decreased with increasing memory load, which was particularly evident in the CONV group. Patients on RLAI and controls demonstrated task-dependent decreases in activation in medial PFC, whereas the CONV group overactivated that region. The CONV group also showed underactivation of VLPFC compared with controls under conditions of increasing memory load, with the RLAI group showing an activation pattern not significantly different from either group. We conclude that RLAI may contribute to normalization of brain activation in regions involved in working memory functioning in people with chronic schizophrenia.