Narrow and broad definition of mixed-handedness in male psychiatric patients.

Differences in assessment and classification procedures of many mixed-handedness studies have made comparison of findings difficult. In the present study, "narrow" and "broad" definitions of mixed-handedness were investigated using the Annett Handedness Questionnaire in patients with schizophrenia (n=68), panic disorder (n=62), borderline personality disorder (n=35), heroin addiction (n=54), and mental retardation (n=33) in comparison with 944 controls. According to the "narrow" definition of mixed-handedness, an excess of mixed-handedness was observed in patients with borderline personality disorder and mental retardation. An excess of nonmixed-handedness was found in patients with panic disorder. According to the "broad" definition of mixed-handedness, an excess of mixed-handedness was observed in patients with mental retardation, in the total sample of psychiatric patients (n=252), and in the schizophrenic patients. Thus, we can conclude that different mixed-handedness definitions can be associated with different results. Furthermore, we suggest that the neurotic part of the present psychopathology spectrum tends to be related to an excess of normal or nonmixed-handedness, and the psychotic as well as the organic portion is associated with an excess of mixed-handedness, regardless of the definition of mixed-handedness used.