Methylphenidate-Induced Information Processing Dysfunction in Nonschizophrenic Patients

• To examine the relationship of aminergic overactivity to information processing, we gave methylphenidate hydrochloride, oxazepam, or placebo to 12 nonpsychotic patients in one-week blocks in a double-blind, randomized design. Methylphenidate induced a pattern of information processing dysfunction similar to that seen in schizophrenic patients, strengthening the linkage of the schizophrenia—information processing dysfunction—aminergic overactivity relationship. Further, the time course of the observed deficits in both schizophrenic and methylphenidate-induced states is strikingly compatible with the temporal mapping pattern of monoaminergic neuronal systems. More research is needed to identify definitively the aminergic influences on attentional functioning. A psychophysical task—pharmacologic probe strategy should prove useful.