Smooth-pursuit eye-tracking dysfunction is a putative genetic trait marker for schizophrenia. In this study 88 Japanese schizophrenics from Kyushu and Okinawa were examined for the marker using precise high-resolution instrumentation: 76% of the schizophrenics from Kyushu and 89% of those from Okinawa had pursuit dysfunction. The presence of the culture-neutral smooth-pursuit marker for schizophrenia in Japan demonstrates that the etic concept “schizophrenia” is cross-culturally valid. Furthermore, the ubiquity of the marker in biologically and culturally diverse populations may indicate a limit on the extent of meaningful heterogeneity likely to be discovered within the condition.
Allen, John S.; Matsunaga, K.; Nakamura, T.; Kitamura, F.; Furukawa, T.; Hacisalihzade, S. S.; Sarich, V. M.; and Stark, L.
"Schizophrenia, Eye Movements, and Biocultural Heterogeneity,"
3, Article 2.
Available at: http://digitalcommons.wayne.edu/humbiol/vol62/iss3/2