Creatine kinase elevations and aggressive behavior in hospitalized forensic patients.

The relationship between creatine kinase (CK) and aggressive behavior was tested in 195 males consecutively admitted to a forensic hospital. Among patients receiving antipsychotic medication, the most violent patients had higher CK levels than less violent patients. This was not the case in patients who did not receive antipsychotic medication. CK levels were not influenced by age, ethnicity, or clinical diagnosis. CK levels were however influenced by prior assaultiveness and restraints. When these two factors were controlled for, CK levels remained strongly associated with subsequent violence. CK appears to be a potential predictor of violent behavior. It has the advantage of easy availability in comparison to other biological markers of aggression (e.g., 5-HIAA). Prospective studies are needed to confirm the validity of this biobehavioral association.