REDUCED LATENT INHIBITION IN PEOPLE WITH SCHIZOPHRENIA - AN EFFECT OFPSYCHOSIS OR OF ITS TREATMENT

Background People with schizophrenia show impaired attention. This cou ld result from reduced latent inhibition (a measure of ability to filt er out irrelevant stimuli). Previous studies have found reduced audito ry latent inhibition in people with acute schizophrenia: we tested whe ther this results from psychosis or from drug treatment. Method We mea sured auditory latent inhibition in two studies. One compared antipsyc hotic-naive people with acute schizophrenia with patients within two w eeks of starting antipsychotic treatment. The second compared healthy volunteers given either saline or 1.0 mg haloperidol, intravenously. R esults Latent inhibition was absent in treated patients, but was clear ly present in patients who were naive to antipsychotics. Latent inhibi tion was absent in volunteers given haloperidol, but was clearly prese nt in those given saline. Conclusions The reduced auditory latent inhi bition seen in acute schizophrenia is more plausibly due to antipsycho tic treatment than to the disorder. Unless neuropsychological models o f schizophrenia incorporate evidence from drug-free patients and drug- treated healthy controls, they may be invalid.