Page 211 - Read Online

THE ROLE OF MICROSTRUCTURAL WM BRAIN FA values in the right superior frontal gyrus WM of
ABNORMALITIES AS ASSESSED BY DIFFUSION depressed patients than controls.
TENSOR IMAGING IN PATIENTS WITH UNIPOLAR
MAJOR DEPRESSION de Kwaasteniet et al. [21] demonstrated that WM
integrity of the uncinate fasciculus was reduced and
An important contribution to the understanding of that functional connectivity between the subgenual
the role and significance of WMHs in patients with anterior cingulate cortex and medial temporal lobe was
mood disorders arrived from the most recent magnetic increased in 18 MDD patients when compared with
resonance techniques such as DTI. Since 2002, when 24 healthy controls. A negative correlation between
Alexopoulos et al. [75] reported an association between uncinate fasciculus integrity and subgenual anterior
lower fractional anisotropy (FA) of the right and left cingulate cortex functional connectivity with the
frontal WM regions with a low remission rate, several bilateral hippocampus was also observed only in
other DTI studies found an association between MDD subjects.
microstructural WM abnormalities and MDD. These [79]
authors identified for the first time the presence Previously, Bae et al. reported significantly lower
of microstructural WM abnormalities lateral to the FA values in WM of the right anterior cingulate cortex,
anterior cingulate and hypothesized that they were bilateral superior frontal gyri and left middle frontal
associated with a low rate of remission in 13 patients gyrus of 106 elderly depressed subjects. Furthermore,
a significant reduction in FA values of widespread
with geriatric MDD.
regions of the frontal and temporal lobes in 13 patients
with LOD was found by Nobuhara et al. Interestingly,
[80]
Very recently, Qin et al. reported that the hubs of WM
[11]
brain networks consisting of the bilateral dorsolateral the severity of depression was inversely related to
part of superior frontal gyrus, left middle frontal gyrus, reduce FA values of the inferior frontal region.
bilateral middle temporal gyrus, and bilateral inferior Zhang et al. [81] have previously reported that in a cohort
temporal gyrus may accurately distinguish patients with of 21 MDD subjects depression severity had a significant
MDD from healthy controls. Lai and Wu [13] suggested negative correlation with normalized number of fibers
that 44 patients with MDD had significantly lower in the right uncinate fasciculus. Similarly, Steffens
FA values in the left SLF as well as the right anterior et al. [82] reported a significant association between left
thalamic radiation when compared with 27 healthy uncinate fasciculus FA and resting state functional
controls. These patients had also increased radial connectivity between the left ventrolateral prefrontal
diffusivity values in the bilateral SLF and decreased cortex/left amygdala and between the left ventrolateral
axial diffusivity values in the bilateral anterior thalamic prefrontal cortex/left hippocampus. A significant
radiation. The authors suggested that FA values resulted negative correlation has also been suggested between
negatively associated with depression severity in the left ventromedial prefrontal cortex‑caudate resting state
SLF, and illness duration in the right SLF and anterior functional connectivity and left, but not right, uncinate
thalamic radiation. fasciculus FA in 24 older patients remitted from MDD.

Another recent DTI study [19] found that adolescents Another DTI study analyzed the integrity of the WM
with depression had significantly lower FA and higher of corpus callosum and its sub‑regions in 16 subjects
radial diffusivity in bilateral uncinate fasciculus. affected by MDD and 16 age‑ and gender‑matched
According to tract‑based spatial statistics findings, healthy controls. [23] The authors reported that the
lower WM FA values have been associated with corpus callosal area of the genu was smaller in MDD
the limbic‑cortical‑striatal‑thalamic circuit, corpus participants than in 16 healthy controls.
callosum, and anterior and superior corona radiata.
Similar findings have been replicated in adult subjects
In 2007, Li et al. [76] found microstructural alterations in with treatment‑responsive MDD by Guo et al. [83] The
prefrontal WM occurring early in the course of MDD authors found lower FA values in the bilateral internal
of 19 first‑episodes, untreated MDD young adults capsule, genu of corpus callosum, bilateral anterior
relative to healthy controls. In a similar cohort (14 corona radiata, and right external capsule of 22 patients
first‑episode, treatment‑naive young adult MDD compared to 19 healthy subjects.
subjects), Ma et al. [77] found significantly lower FA
values than controls in the WM of the right middle Recently, Korgaonkar et al. [29] suggested that anterior
frontal gyrus, left lateral occipitotemporal gyrus, and cingulate‑limbic WM may be a useful predictor of
subgyral and angular gyri of the right parietal lobe. antidepressant treatment outcome in 74 MDD patients
Moreover, Taylor et al. [78] reported significantly lower who completed 8‑week antidepressant treatment. The

Neuroimmunol Neuroinflammation | Volume 2 | Issue 4 | October 15, 2015 203