Familial transmission of two independent saccadic abnormalities in schizophrenia

Difficulties with inhibiting inappropriate responses, i.e. disinhibition, and problems with spatial memory are both presumed to be a part of the phenotypic expression of the genetic risk for schizophrenia. Schizophrenic probands are impaired on saccadic eye movement tasks which require (a) response inhibition to prepotent stimuli and (b) generation of an accurate response to a remembered or calculated spatial location, but it is unknown how these deficits are inherited. Sixteen schizophrenic probands, their 32 parents, and two normal control groups completed a delayed oculomotor response and an antisaccade task. The parents with a positive ancestral family history for chronic psychosis (n = 8) were presumed to be more likely than their family history-negative spouses to be genetic carriers for schizophrenia. Probands and their positive family history parents had more failures of response inhibition than did normal control groups. However, it was the probands and their negative family history spouses who demonstrated impaired accuracy of the remembered- or antisaccades. Disinhibition may be closely tied to a specific genetic risk for schizophrenia. However, a second familial factor related to the maintenance or manipulation of spatial information may also contribute to the genetic risk of the full clinical disorder.