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The presence of low IQ and mental retardation among murder defendants referred for pretrial evaluation.

Dwyer RG, Frierson RL

Department of Neuropsychiatry and Behavioral Science, University of South Carolina School of Medicine, Columbia, SC 29203, USA. gdwyer@gw.mp.sc.edu

After an overview of definitions of mental retardation and recent case law regarding mental retardation and the death penalty, this paper presents a study of factors associated with a mental retardation (MR) diagnosis among murder defendants. Subjects with a full-scale IQ< or =70 (n=42) were compared with other pretrial murder defendants (n=228) referred for forensic evaluation over a 5-year period. Subjects with an IQ< or =70 who were diagnosed with MR were compared with subjects with an IQ< or =70 who did not receive this diagnosis. Female murder defendants were more likely to receive a diagnosis of MR (p=0.03). MR was also more commonly diagnosed in subjects with an Axis I cognitive disorder (p=0.018). Having an IQ< or =70 was more common in subjects with a psychotic and substance use disorder (p=0.03) and did not necessarily lead to a diagnosis of MR in this subgroup. Implications for diagnosing MR among murder defendants are discussed.

Published 15 May 2006 in J Forensic Sci, 51(3): 678-82.
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