Serum Levels of Thyroid Hormones as Biological Markers in a Swedish Forensic Psychiatric Population

Background:In a Swedish study, delinquent boys had high serum levels of triiodothyronine (T3). Furthermore, former delinquents, followed up after about 30 years, had T3 levels significantly related to repeated criminality. The aim of the present study was to shed further light on the relationship between the thyroid hormones and specific behaviors and personality characteristics. Methods:Serum levels of T3 and free thyroxine (FT4) were measured in 61 nonpsychotic male subjects at forensic psychiatric examinations and 66 normal controls. Psychopathy was determined by means of the Psychopathy Checklist-Revised (PCL-R) and DSM-III-R, DSM-IV, and ICD-10 diagnoses. Results:The study population had high T3 and low FT4 values. Elevated T3 levels were related to type II alcoholism, Cluster B personality disorders, psychopathy as measured by the PCL-R, criminality, a diagnosis of a DSM-IV antisocial disorder, and an ICD-10 dissocial disorder. Serum levels of FT4 were negatively related to the same disorders and personality traits. Conclusions:The results indicate an intimate relationship between T3 and FT4, and abuse and antisocial behavior. They emphasize the importance of further studies on T3 as a biological marker for abuse, social deviance, and repeated violent behavior.