Smooth pursuit eye movements in schizophrenia and attentional dysfunction: adults with schizophrenia, ADHD, and a normal comparison group

Background: Smooth pursuit eye movement (SPEM) abnormalities are found in schizophrenia. These deficits often are explained in the context of the attentional and inhibitory deficits central to schizophrenia psychopathology. It remains unclear, however, whether these attention-associated eye movement abnormalities are specific to schizophrenia or are a nonspecific expression of attentional deficits found in many psychiatric disorders. Adult attention-deficit/hyperactivity disorder (ADHD) is an alternative disorder with chronic attentional and inhibitory dysfunction. Thus, a comparison of SPEM in adult schizophrenia and adult ADHD will help assess the specificity question. Methods: SPEM is recorded during a 16.7° per second constant velocity task in 17 adults with ADHD, 49 adults with schizophrenia, and 37 normal adults; all groups included individuals between ages 25–50 years. Results: Smooth pursuit gain and the frequency of anticipatory and leading saccades are worse in schizophrenic subjects, with normal and ADHD subjects showing no differences on these variables. Conclusions: Many attention-associated SPEM abnormalities are not present in most subjects with ADHD, supporting the specificity of these findings to the attentional deficits seen in schizophrenia.