Blunted inhibition of return in schizophrenia-evidence from a longitudinal study

Previous cross-sectional studies on covert orienting of visual attention in schizophrenia have been inconsistent. In the present longitudinal study, we examined 40 medicated acutely ill inpatients with a covert orienting of attention task (COVAT) shortly after admission, and again 12-16 weeks after the initial examination, while most patients were in (partial) remission. We administered a COVAT with nonpredictive peripheral cues and two stimulus-onset asynchronies (SOA; 100 and 800 ms). In addition, we examined 34 healthy control subjects twice (2 weeks apart). The most important finding was a lack of inhibition of return (IOR) in patients with schizophrenia, both at the first examination in an acute psychotic state and at the follow-up examination after considerable clinical improvement. The IOR deficit was unrelated to psychopathology, length of illness, number of previous psychotic episodes, and type of neuroleptic (NL) medication. Deficient IOR in patients with schizophrenia appears to be state-independent and might be viewed as a trait or vulnerability marker of the disorder. Subsequent studies with never-medicated populations and with schizotypal or high-risk subjects are needed in order to further analyze the possible role of NL medications and to clarify whether blunted IOR might represent a vulnerability marker of schizophrenia.