Cognitive impairment, manifested as mild to moderate deviations from psychometric norms, is present in many but not all schizophrenia patients. The purpose of the present study was to compare the effect of haloperidol with that of second-generation antipsychotic drugs on the cognitive performance of patients with schizophreniform disorder or first-episode schizophrenia.

Davidson M, Galderisi S, Weiser M, Werbeloff N, Fleischhacker WW, Keefe RSE, Boter H, Keet IPM, Prelipceanu D, Rybakowski JK, Libiger J, Hummer M, Dollfus S, Lopez-Ibor JJ, Hranoy LG, Gaebel W, Peuskens J, Lindefors N, Riechler-Rossler A, Kahn RS. Cognitive effects of antipsychotics drugs in first-episode schizophrenia and schizophreniform disorder:  A randomized, open-label clinical trial (EUFEST).  The American Journal of Psychiatry, 2009; 166(6): 675-682.