Performance of the continuous performance test among community samples

The Continuous Performance Test (CPT) has been modified to be used widely as a potential vulnerability marker of schizophrenia. In genetic analyses of schizophrenia, well-established norms for the CPT are essential in choosing a suitable threshold of CPT for classifying subjects as affected or unaffected. In this study, we investigated the performance of 115 adolescents and 345 adults, randomly sampled from a community, on two sessions of the CPT 1-9 (undegraded and 25% degraded). The results showed that an older age was associated with a decreasing hit rate and sensitivity (d'), while a higher level of education was associated with an increasing hit rate and d' for both sessions of the CPT. Men had higher hit rates and d' than women for the degraded CPT. A practice effect during the second session of the CPT was noted among 20 to 33 percent of the subjects. Poorer CPT performance was associated with schizotypy measured by the Perceptual Aberration Scale and the Schizotypal Personality Questionnaire. Thus, in assessing CPT performance among schizophrenia patients or high-risk populations, we must compare their results to age-, education-, and sex-corresponding norms. The data presented in this report will be valuable in this regard.