Sustained attentional performance in patients with schizophrenia

Abstract

Two tests of sustained attention were administered to three groups of participants (n = 51 each): chronic schizophrenia, traumatic brain injury (TBI) and healthy controls, matched for age, education and gender. The monotone counting task required participants to count the total number of tones in a series of trial. The sustained attention response to task (SART) required participants to refrain from responding to randomly presented targeted stimuli (digit) but to respond to non-targeted stimuli. Three major findings were found in these comparisons. In general, patients with schizophrenia performed the worst in both tasks among the three groups. Second, schizophrenic patients performed significantly worse in monotone counting than the SART [t950 = 2.479, p = 0.017]. The effect size was found to be modest to large (0.46). Third, a reverse pattern was observed in patients with TBI: they tended to have a higher proportion of SART correct response and lower proportion of monotone counting [t(50) = 1.792, p = 0.079; effect size of 0.27]. However, such reversed pattern disappeared after partialling out the accuracy–speed trade-off component. The SART performance was consistently and significantly worse than the monotone counting task among the three groups (p < 0.005.. Taken together, these findings suggest that although both the monotone counting task and SART were impaired in patients with schizophrenia and TBI, the severity and modality of such impairments were qualitatively different in these patient groups.