Orienting of attention in unmedicated patients with schizophrenia, prodromal subjects and healthy relatives

In typical orienting of attention tasks subjects have to respond as fast as possible to targets which appear in the periphery of the visual field and are preceded by spatial cues (e.g. brightening of a peripheral box where the target may subsequently appear). Reaction times (RT) are facilitated when cue and target appear at the same location (valid cueing) and the cue target interval is short (<250 ms). However, RTs slow down again when the target follows a valid cue after an interval of 250 ms and longer. This latter phenomenon is called Inhibition of Return (IOR) and is thought to reflect an automatic, inhibitory mechanism to protect the organism from redundant and distracting stimuli. Deficits of IOR were repeatedly reported in patients with schizophrenia. However, the role of medications and the nature of the deficit (trait or vulnerability indicator?) were unclear. In the present study we examined 15 unmedicated patients with schizophrenia (age: 31.2+/-11.1, m/f: 11/4, global scores SAPS: 48.33+/-33.09, SANS: 19.22+/-26.16), 29 subjects who were putatively in a prodromal state of psychosis, 30 first-degree relatives, another 8 first-degree relatives who had one child and at least one more relative with schizophrenia, and 50 healthy controls. We found an impairment of IOR only in the unmedicated patient group. In conclusion, blunted IOR in schizophrenia is not secondary to medications. According to this and previous studies blunted IOR may be most probably viewed as a trait cognitive feature of the schizophrenic disorder.