Neuroanatomical and physiological changes have been identified in patients diagnosed with late-life depression (MDD) using magnetic resonance imaging (MRI) techniques. These include a decrease in the volumes of specific brain regions and an increase in high intensity lesions when compared with non-depressed controls. Smaller brain volume have been identified primarily in the prefrontal region/sub regions, head of the caudate nucleus and the hippocampus in patients with MDD. High intensity lesions occur predominantly in the periventricular and deep white matter regions of the parenchyma. More recently, attention has been focused on the biological integrity of "normal appearing white matter (NAWM) in patients with mood disorders. MRI approaches such as magnetization transfer (MT), spectroscopy (MRS) and diffusion tensor imaging (DTI) have been exploited to characterize white matter changes in vivo in patients with depression. MRS studies indicate that levels of choline and myoinositol are higher in the dorsolateral white matter in depressed patients when compared with controls. MT studies reveal lower MT ratios (indicative of demyelination and axonal damage) in normal appearing white matter regions of the brain. Recent DTI data demonstrate findings suggestive of biological abnormalities white matter tracts in elderly patients when compared with controls. These observations are intriguing and open up a 'new" field of scientific inquiry in mood disorders research - the role of white matter abnormalities in the pathophysiology of late-life depression. This presentation, will focus on the MRI methods used and the principal findings to emerge in this area of research. The clinical and behavioral implications of these observations will be discussed together with possible treatment implications.
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