Is the modality-shift effect specific for schizophrenia patients?

Several studies have found that the reaction time of schizophrenia patients is longer when successive imperative stimuli are of different modality (e.g., light followed by sound) than when they are identical (e.g., sound followed by sound). This effect is called the modality-shift effect. In this study, the reaction times of 175 persons were analyzed: 54 schizophrenia patients, 33 patients with mood disorders, 13 alcoholics, 17 patients with rheumatoid arthritis, 13 patients with internal diseases, and 45 normal controls. The results indicated that a shift from light to sound stimuli lengthened the reaction time for schizophrenia patients considerably more than for alcoholics, patients with rheumatoid arthritis, patients with internal diseases, or normal controls. No difference was found between the reaction times of schizophrenia patients and patients with mood disorders.