Forest plot of effect sizes of α7 nicotinic agonists on overall cognitive index and attention for subjects with schizophrenia and Alzheimer’s disease. Meta-analysis demonstrated no significant effect on overall cognition (A) compared to placebo (Effect size (ES) = −0.057, 95% CI = −0.16 to 0.044, p = 0.27), and no significant effect on attention (B) compared to placebo (ES = −0.077, 95% CI = −0.20 to 0.047, p = 0.22). Note: negative effect size favors drug treatment.