Original articleMedial orbital frontal lesions in late-onset depression
Introduction
The causes of depression in the elderly are poorly understood (Byrum et al 1999). Genetic factors are of less significance in patients presenting with depression for the first time late in life (Krishnan et al 1997). Thus, other factors are believed to play a role in the etiopathophysiology of late-onset depression. Early studies using magnetic resonance imaging (MRI) suggested that subcortical vascular changes are more prevalent in late-life depression and that they may play a role in the pathophysiology of depression (Krishnan et al 1997). The importance of these changes has also been demonstrated in a recent epidemiologic study (Steffens et al 1999). Studying the location of the lesion relative to the occurrence of depression could be critical in delineating the neuroanatomic substrates of depression. The purpose of this study was to characterize these lesions in terms of location by development of statistical parametric maps of lesions that differentiate patients from control subjects.
Section snippets
Methods and materials
Magnetic resonance images were acquired for 88 elderly depressed subjects (age range 63–80 years, 63 female), assessed using the Duke Depression Evaluation Schedule (George et al 1989) and enrolled in the Duke University Clinical Research Center for the Study of Late-Life Depression, and 47 age- and gender-matched nondepressed subjects (control subjects) after obtaining written informed consent under a protocol approved by the Duke Institutional Review Board. All patients met DSM-IV criteria
Results
There was a higher rate of vascular disease in the control subjects (34) who were recruited to have a greater risk for vascular disease than in patients (38; χ2 = 10.8, p < .001). Subcortical hyperintensity was greater in patients than in control subjects (0 and 1 vs. 2 and 3; χ2 = 7.32, p < .006). Large deep white matter hyperintensities were also greater in depressed patients, although this did not reach significance (3 vs. rest, χ2 = 2.85, p < .09). The SPM analysis between groups showed two
Discussion
This study, in conjunction with other literature on the role of this part of the prefrontal cortex, suggests a critical role for these lesions in the pathophysiology of depression in late life. Previous studies with rating scales have provided evidence that large lesions, especially in the frontal cortex and basal ganglia, are related to depression. This study is the first to more precisely localize the lesions. The regions identified are consistent with other data in the literature (Ongur et
Acknowledgements
This study was sponsored by the National Institute of Mental Health (Grant No. MH40159).
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