Ethnicity, aggression and serum creatine kinase in hospitalized male forensic patients.

OBJECTIVE: This study examined the relationship of serum creatine kinase (CK) levels with aggressive behavior as a function of psychosis and ethnicity in a sample of violent forensic patients. DESIGN: CK levels were determined on admission in a sample of 195 males consecutively admitted to a forensic hospital. The patients' aggressive behavior during their hospital stay was monitored using the Overt Aggression Scale (OAS). All data for this study was archival and gathered from hospital records. METHODS: Multivariate analysis of variance was used to examine whether African-American and Caucasian patients differed in serum CK levels and severity, frequency, and type (verbal vs physical) of aggression. T-tests were performed to compare ethnic groups in terms of age, weight, height, systolic and diastolic blood pressure. All patients who had been in restraints, had been administered intramuscular medications, had a history of drug or alcohol abuse, and were classified as schizophrenic were compared using chi-square analysis. For each of these variables further comparisons were made of CK levels between African-American and Caucasian patients. RESULTS: Mean serum CK in African-American patients was 64% higher than in Caucasians. African Americans displayed significantly greater physical aggression than Caucasian patients. In addition, African-American patients with a diagnosis of schizophrenia had significantly higher CK levels than African Americans with other diagnoses, with no significant differences related to schizophrenia noted within the Caucasian group. No significant differences in aggressive behavior related to schizophrenia were found in African-American patients. CONCLUSIONS: This study confirms the findings of previous reports which observed higher CK levels in African Americans than in Caucasians. It is also proposed that a confluence of physiologic and psychosocial factors may affect biological marker presentation, particularly as manifest in CK differences between ethnic groups.