Diffuse microstructural abnormalities of normal-appearing white matter in late life depression: a diffusion tensor imaging study.
BACKGROUND
Many recent studies have identified white matter abnormalities in late life depression (LLD). These abnormalities include an increased volume of discrete white matter hyperintensities on T2-weighted imaging (WMH) and changes in the diffusion tensor properties of water. However, no study of LLD to date has examined the integrity of white matter outside of WMH (i.e., in normal-appearing white matter).


METHODS
We performed T1- and T2-weighted imaging as well as diffusion tensor imaging (DTI) in depressed elderly subjects (n = 73) and nondepressed control subjects (n = 23) matched for age and cerebrovascular risk factors. The structural images were segmented into white matter, gray matter, cerebrospinal fluid, and WMH. The DTI parameters were calculated in white matter regions of interest after excluding the WMH.


RESULTS
Compared with control subjects, in the LLD group there were widespread abnormalities in DTI parameters, particularly in prefrontal regions. From a comprehensive neuropsychological battery, the strongest correlations were observed between cognitive processing speed and DTI abnormalities.


CONCLUSIONS
These results suggest that further investigation is warranted to determine potential reversibility and/or prognosis in LLD.
Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA.
Joshua S
JS
Shimony
Yvette I
YI
Sheline
Gina
G
D'Angelo
Adrian A
AA
Epstein
Tammie L S
TL
Benzinger
Mark A
MA
Mintun
Robert C
RC
McKinstry
Abraham Z
AZ
Snyder
D000368:Aged; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D001931:Brain Mapping; D003863:Depression / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged