The effect of antipsychotic medication on neurocognitive function remains controversial, especially since most previous work has compared the effects of novel antipsychotic medications with those of high doses of conventional medications. This study compares the neurocognitive effects of olanzapine and low doses of haloperidol in patients with first-episode psychosis.

Keefe RSE, Seidman LJ, Christensen BK, Hamer RM, Sharma T, Sitskoorn M, Lewine RRJ, Yurgelun-Todd D, Gur RC, Tohen M, Tollefson GM, Sanger TM, Lieberman JA, and the HGDH Research Group. Comparative effect of atypical and conventional antipsychotic drugs on neurocognition in first-episode psychosis:  A randomized double-blind trial of olanzapine versus low-dose haloperidol.  American Journal of Psychiatry, 2004; 161(6): 985-995.