1. ¹MOOD-CNS Program (Mood Disorders Clinical Neurosciences Program), Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
2. ²South Texas Veterans Health Care System, Audie L Murphy Division, San Antonio, TX, USA
3. ³Department of Psychiatry, Dokuz Eylül University School of Medicine, Izmir, Turkey
4. ⁴Deparment of Orthodontics, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
5. ⁵Department of Pathology and Experimental and Clinical Medicine, Section of Psychiatry, University of Udine, Udine, Italy
6. ⁶Scientific Institute IRCCS E Medea, Pasian di prato, Udine, Italy
7. ⁷Interdisciplinary Lab of Neuroimaging and Cognition (LiNC), Department of Psychiatry, Federal University of Sao Paulo, Sao Paulo, Brazil
8. ⁸Institute of Psychiatry, University of Sao Paulo School of Medicine, Sao Paulo, Brazil
9. ⁹Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
10. ¹⁰Department of Psychiatry and Behavioral Sciences, Wayne State School of Medicine, Detroit, MI, USA
11. ¹¹Department of Radiology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA

Correspondence: Dr JC Soares, Division of Mood and Anxiety Disorders, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA. E-mail: soares@uthscsa.edu

Received 3 February 2006; Revised 8 August 2006; Accepted 13 September 2006; Published online 5 December 2006.

Abstract

Our knowledge about the neurobiology of suicide is limited. It has been proposed that suicidal behavior generally requires biological abnormalities concomitant with the personality trait of impulsivity/aggression, besides an acute psychiatric illness or psychosocial stressor. We investigated fronto-limbic anatomical brain abnormalities in suicidal and non-suicidal adult female patients with unipolar depression. Our sample consisted of seven suicidal unipolar patients, 10 non-suicidal unipolar patients and 17 healthy female comparison subjects. The criterion for suicidality was one or more documented lifetime suicide attempts. A 1.5T GE Signa Imaging System running version Signa 5.4.3 software was used to acquire the magnetic resonance imaging images. All anatomical structures were measured blindly, with the subjects' identities and group assignments masked. We used analysis of covariance with age and intracranial volume as covariates and the Tukey–Kramer procedure to compare suicidal patients, non-suicidal patients and healthy comparison subjects. Suicidal patients had smaller right and left orbitofrontal cortex gray matter volumes compared with healthy comparison subjects. Suicidal patients had larger right amygdala volumes than non-suicidal patients. Abnormalities in the orbitofrontal cortex and amygdala in suicidal patients may impair decision-making and predispose these patients to act more impulsively and to attempt suicide.