Sustained attention deficit and schizotypal personality features in nonpsychotic relatives of schizophrenic patients.
OBJECTIVE
The authors investigated whether nonpsychotic relatives of schizophrenic probands have an elevated risk of deficits in sustained attention as measured by the Continuous Performance Test (CPT), whether such deficits are associated with specific factors of schizotypy, and whether poor CPT performance by probands predicts poor performance by their relatives. In addition, the heritability of CPT performance in the families of schizophrenic probands was estimated.


METHODS
The study subjects were 60 schizophrenic probands, 148 of their first-degree relatives, 20 normal comparison probands, and 42 of the comparison probands' first-degree relatives. Subjects completed undegraded and 25% degraded sessions of the CPT and were interviewed with use of the Chinese version of the Diagnostic Interview for Genetic Studies. Subjects' CPT sensitivity indexes, d', were standardized against those of a community sample of 345 subjects, with adjustment for age, sex, and level of education.


RESULTS
On average, the d' values of the relatives of schizophrenic probands were lower than those of the relatives of comparison probands but higher than those of schizophrenic probands. Lower sensitivity indexes among the relatives of schizophrenic patients were associated with the interpersonal dysfunction and disorganization factors of schizotypy but not the cognitive/perceptual factor. When schizophrenic probands were divided into two subgroups by a cutoff of -3.0 for adjusted z score on the CPT, the d' values of relatives of probands with CPT deficits were lower than those of relatives of probands without deficits. The estimated heritability of performance on the CPT ranged from 0.48 to 0.62.


CONCLUSIONS
Sustained attention deficit may be a genetic vulnerability marker for schizophrenia, and it may be more useful in linkage analysis than traditional phenotype definitions of schizophrenia.
Chen
W J
WJ
Institute of Epidemiology, College of Public Health, National Taiwan University, Taipei.
Liu
S K
SK
Chang
C J
CJ
Lien
Y J
YJ
Chang
Y H
YH
Hwu
H G
HG
D000328:Adult; D001288:Attention; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D015897:Comorbidity; D005190:Family; D005260:Female; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011597:Psychomotor Performance; D011930:Reaction Time; D012559:Schizophrenia / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D012565:Schizophrenic Psychology; D012569:Schizotypal Personality Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D013624:Taiwan / Q000453:epidemiology
D005819:Genetic Markers