Comparison of the effectiveness of Conners' CPT and the CPT-identical pairs at distinguishing between smokers and nonsmokers with schizophrenia

Sustained attention deficits and high rates of smoking are often observed in patients with schizophrenia. This has led to the hypothesis that patients may smoke as an attempt to ameliorate cognitive deficits related to abnormal nicotinic structure and function. Continuous performance tasks (CPT) are often used to index sustained attention deficits in patients with schizophrenia, however, there are important differences between tasks that may impact performance in smokers and nonsmokers with schizophrenia differently. The Conners' CPT (C-CPT) has a high signal-to-noise ratio and is commonly used to assess impulsivity. The CPT-Identical Pairs (CPT-IP) has a low signal-to-noise ratio and is commonly used to assess negative symptoms in patients with schizophrenia. We sought to determine whether there were differences of sustained attention between patient smokers vs. nonsmokers, and if one CPT would provide a better separation of sustained attention between groups. Results revealed that both instruments detect more impaired sustained attention deficits in patient smokers compared to nonsmokers. Patient smokers performed significantly worse on the majority of the CPT-IP composite scores compared to the C-CPT composite scores. These results do not support the self-medication theory, as patient smokers performed worse than patient nonsmokers. Researchers studying sustained attention in schizophrenia may wish to consider the CPT-IP over the C-CPT, as well as control for smoking status.