Background: Within the field of genetic schizophrenia research, eye-trackin
g dysfunction can be regarded as a putative trait marker in families with m
ultiple occurrences of the disease (familial schizophrenia). We concentrate
d on families with single occurrences of schizophrenia (sporadic schizophre
nia) to test whether a genetic factor may be present in these families as w
ell.
Methods: Eye movements were recorded using infrared oculography in eight fa
milies with sporadic schizophrenia (44 members), eight families with famili
al schizophrenia (66 members), and nine nonpsychotic families (77 members).
Triangle-wave stimuli at 15 degrees/sec and 30 degrees/sec were used, and
gains (eye velocity/target velocity), rates, and amplitudes of saccades (cl
assified as catch-up and anticipatory saccades) were determined
Results: I) In sporadic-schizophrenia families, gain values, saccade rates,
and anticipatory saccade amplitudes at 30 degrees/sec differed in a statis
tically significant fashion from nonpsychotic families, but not from famili
es with multiple occurrences of schizophrenia, and 2) at 30 degrees/sec, a
significant effect of target direction on smooth-pursuit maintenance was ob
served in both sporadic- and familial-schizophrenia families.
Conclusions: Our results support the hypothesis that genetic factors may be
present even in sporadic-schizophrenia families and may contribute to a mo
re precise and biologically based definition of the schizophrenia phenotype
in future molecular genetic analysis. (C) 2000 Society of Biological Psych
iatry.