Early expression of smooth-pursuit eye movement abnormalities in children of schizophrenic parents.
OBJECTIVE
Disordered smooth-pursuit eye movements (SPEM) and, specifically, small anticipatory saccades that disrupt SPEM have been hypothesized to be a marker of genetic vulnerability to schizophrenia. This study compares SPEM in children of schizophrenic parents with normally developing control children to assess whether SPEM abnormalities are also present in a subset of at-risk children.


METHODS
With infrared oculography, SPEM was examined in 13 children of schizophrenic parents and 19 normally developing controls (aged 6 to 15 years). Measures of smooth-pursuit gain and root mean square error were used in addition to more specific measures of catch-up saccades and anticipatory saccades.


RESULTS
Children of schizophrenic parents differed from normally developing controls on gain and root mean square error, but not on catch-up saccades. Small anticipatory saccades were significantly more frequent in the at-risk group. The percentage of total eye movements due to anticipatory saccades identified 54% of the at-risk group (compared with none of the control group) as performing more than two standard deviations above (worse than) the control mean.


CONCLUSIONS
The presence of increased anticipatory saccades is evidence for an oculomotor dysfunction that may be a phenotype of the genetic risk for schizophrenia, expressed years prior to the possible development of clinical illness.
Ross
R G
RG
University of Colorado Health Sciences Center, Denver, USA. randy.ross@uchsc.edu
Hommer
D
D
Radant
A
A
Roath
M
M
Freedman
R
R
D000293:Adolescent; D002648:Child; D016241:Child of Impaired Parents / Q000523:psychology*; D004585:Electrooculography; D005260:Female; D006801:Humans; D008297:Male; D011698:Pursuit, Smooth / Q000235:genetics*; D012307:Risk Factors; D012438:Saccades / Q000235:genetics; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics*; D012569:Schizotypal Personality Disorder / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology