Planning ability in familial and non-familial schizophrenia

Abstract

Objective: To explore planning ability in familial and nonfamilial forms of schizophrenia by examining a sample of schizophrenic patients from multiply and singly affected families, their healthy relatives and normal controls. Methods: Two groups of schizophrenic patients (familial/nonfamilial ), their first-degree healthy relatives and normal controls participated in the study (227 subjects in total). Planning ability was assessed using the 3-D Computerised Tower of London task (Morris et al., 1993) which requires the subject to reproduce a target arrangement in a specified number of moves. Results: Three measures were identified: (1) accuracy of problem solving, (2) planning times and (3) subsequent execution times. Neither familial schizophrenics (z= 1.22, P=0.22) nor their relatives (z=0.38, P=0.69) performed significantly worse than controls on accuracy of problem solving, as defined by the number of moves made above the ideal minimum. Nonfamilial schizophrenics (z=2.53, P=0.01) and their relatives (z = 2.9, P = 0.004) performed significantly worse than controls, on the same measure. There were no significant differences on either planning (Xz=5.63, df=4, P=0.22) or subsequent execution times (Z 2 = 5.16, df = 4, P = 0.27) between the groups. Conclusion: Familial and non-familial forms of schizophrenia might be subject to different aetiological mechanisms.