Mood disorders - review of structural MRI studies

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Mood disorders are significant causes of morbidity and mortality.
• While recognized as brain-based, the precise neural correlates of mood disorders remain unclear.
• A neuro-anatomic model involving the prefrontal cortex, amygdala-hippocampus complex, thalamus, basal ganglia, and their connections has been proposed.

Purpose of the Study:

• To review evidence of regional brain abnormalities in bipolar disorder.
• To integrate findings into a comprehensive pathophysiological model of mood disorders.
• To explore structural brain changes in mood disorders.

Main Methods:

• A comprehensive literature search of Medline Ovid (1966-2002) was performed.
• Manual searches of bibliographical references from recent reviews complemented the computerized search.
• Articles meeting specific inclusion criteria were analyzed.

Main Results:

• Hyperintense lesions in cortical and subcortical regions are consistently reported structural abnormalities.
• Smaller prefrontal cortical volume is a common finding in both bipolar disorder and unipolar depression.
• Enlarged amygdala (bipolar disorder) and smaller hippocampus (unipolar depression) have been observed, alongside varied striatal volume changes.

Conclusions:

• Bipolar and unipolar mood disorders are linked to identifiable structural brain abnormalities.
• The underlying histopathology of these anatomical changes requires further elucidation.
• Prospective longitudinal studies and integration with functional imaging are essential for definitive conclusions.