<qa>  What is the term for aripiprazole treatment?This study hypothesizes that switching to aripiprazole treatment will be associated with reductions in adipose tissue mass in comparison to olanzapine. We hypothesize that aripiprazole treatment will be associated with numerical, but not statistically significant, reductions in comparison to pretreatment with risperidone or quetiapine. We hypothesize that aripiprazole treatment will be associated with no change in comparison to pretreatment with ziprasidone. These hypotheses will be evaluated by measuring body composition using dual energy x-ray absorptiometry DEXA and anthropomorphic measurements to provide estimates of total body fat, abdominal fat and fat-free mass. 