Abnormalities during a smooth pursuit eye movement task (SPEM)
are common in schizophrenic patients and their relatives. This
study assessed various components of SPEM performance in
first-degree unaffected relatives of schizophrenic patients.
One hundred individuals with schizophrenia, 137 unaffected
first-degree relatives, and 69 normal controls completed a
16.7°/s SPEM task. Smooth pursuit gain, catch-up saccades
(CUS), large anticipatory saccades, and leading saccades (LS)
were identified. Groups were compared with parametric and admixture
analyses. Schizophrenic patients performed more poorly than
unaffected relatives and normals on gain, CUS, and LS. Unaffected
relatives were more frequently impaired than normals only on
gain and LS. Relatives of childhood-onset and adult-onset probands
had similar impairments. Gain and frequency of leading saccades
may be genetic endophenotypes in childhood-onset and adult-onset
schizophrenia.