Bd. Schwartz et al., SMOOTH-PURSUIT EYE-MOVEMENT DIFFERENCES BETWEEN FAMILIAL AND NONFAMILIAL SCHIZOPHRENIA, Schizophrenia research, 17(2), 1995, pp. 211-219
Disrupted smooth pursuit eye tracking characterizes a greater proporti
on of individuals with schizophrenia than in the normal population. Th
e finding of a similar increased incidence of eye tracking abnormality
in first degree relatives of schizophrenics implicates this disorder
as a potential biological marker for schizophrenia. To test the assump
tion that the eye tracking dysfunction of schizophrenics is geneticall
y related, left and right smooth pursuit gain and phase shift were com
pared between 20 schizophrenics with a family history of schizophrenia
or schizophrenia-related disorders, 18 schizophrenics without a famil
y history, as well as for 18 normal controls. Subjects tracked pendula
r targets on an LED light bar moving at frequencies of 0.2 and 0.7 Hz.
Horizontal eye movements were recorded using DC-electro-oculography.
Results indicate that schizophrenics with a positive family history ha
d significantly reduced right pursuit gain compared with controls, whi
le right gain for negative family history schizophrenics did not diffe
r from either group. Schizophrenic subjects also were administered neu
ropsychological tests. Linear regression by groups analyses reveal tha
t neuropsychological measures significantly predicted right gain to sl
ower targets (0.2 Hz) for the positive family history schizophrenics,
but not for negative family history schizophrenics.