Executive function and genetic loading in nonpsychotic relatives of schizophrenia patients.

Executive functions meet the "endophenotype candidate" criteria in neuropsychological measures for schizophrenic patients. To determine which area of executive functioning has the greatest value in differentiating the so called "candidate endophenotype" of schizophrenia through comparing the effect sizes of four commonly used executive function tests. A Wisconsin Card Sorting Test, a Stroop Test, a Trail Making Test and a Verbal Fluency Test were used to evaluate executive function in two study groups: healthy relatives of schizophrenia patients from simplex and multiplex families and a healthy control group. In all four tests, study groups performed poorly in contrast to the control group. In the B time, A error and B error results of the Trail Making Test, the multiplex group performed poorly compared to the simplex group; control group did better than both study groups. Our findings support that the presence of a schizophrenia patient in a family predicts worse performance on executive function tests in a group of healthy relatives of that individual. The results of our study suggest that the Trail Making Test in particular may signify a stronger endophenotypic trait.