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in the left sagittal stratum, and reduced FA in the right scores were positively associated with WM volume
cingulate cortex/posterior body of corpus callosum whereas harm avoidance scores were negatively
compared to 20 controls. associated with WM volume in a cohort of 125 healthy
participants.
WMHs AND AFFECTIVE TEMPERAMENTS:
CLINICAL IMPLICATIONS REGARDING MDD AND Moreover, Bjørnebekk et al. [110] reported an association
SUICIDALITY between social reward dependency and WM
microstructure in 263 healthy volunteers. In detail,
Few studies investigated the association between the authors found that increased reward dependence
affective temperaments and WMHs as well as their was associated with reduced FA in anterior brain
possible implications on suicidal risk. areas suggesting that WM fiber tract properties may
significantly modulate individual differences in social
Weber et al. [104] conducted a 2‑year follow‑up study reward. However, no associations were found between
in a cohort of 28 EOD elderly patients and observed novelty seeking behavior as assessed by TCI and DTI
increased neuroticism factor, anxiety facet scores, and indices.
reduced warmth and positive emotions facet scores
only at baseline compared to 48 controls. Significantly Westyle et al. [111] showed that increased harm avoidance
higher depression facet scores at both baseline and after is associated with abnormalities in WM microstructure
2 years independently of depressive relapse were also in a large cohort (n = 263) of healthy adults. Increased
reported in EOD elderly patients than controls. In 2010, harm avoidance was associated with reduced FA
the same research group [105] reported no significant whereas increased mean diffusivity/radial diffusivity in
group differences in WMH rates between 38 EOD and specific WM tracts, such as corticolimbic pathways, was
62 controls. Importantly, EOD was associated with a implicated in emotional processing and reappraisal. The
significant increase of neuroticism and decrease of authors speculated that the associations between WM
extraversion facet scores as assessed by five‑factor microstructure and anxiety‑related personality traits
personality dimensions. emerged early in life suggesting that both temperament
and personality are closely shaped early and remain
Serafini et al. [106] found that patients with higher stable during the life span. [111]
dysthymia and lower hyperthymia scores (as assessed
by TEMPS‑A) were more likely to have higher suicidal There are also two voxel‑based morphometry studies
risk, more recent suicide attempts, and more deep analyzing the association between WM abnormalities
WMHs than patients with higher hyperthymia and and temperamental features in healthy subjects.
lower dysthymia scores. In this study, different
temperament characteristics are reflected by MRI In the first study, Van Schuerbeek et al. [112] suggested
findings. The mentioned results replicate the findings that individual variations in brain morphology
of prior studies showing that depressive, cyclothymic, may be associated with temperament and character
irritable and anxious temperaments may be considered dimensions in 68 young healthy female volunteers.
risk factors for suicidal behavior whereas hyperthymic The authors found correlations between temperamental
temperament is a protective factor, at least for suicide traits and WM volume. Specifically, a link between
attempters. [106,107] cooperativeness and WM volume has been observed
in the medial frontal and precentral gyrus.
There are also DTI studies analyzing the presence
of WM abnormalities in healthy individuals. Picerni In the second study, Kaasinen et al. [113] investigated
et al. [108] investigated the relationship between whether late adulthood brain structural differences
cerebellar macro‑ and micro‑structural variations may be related to differences in temperament and
detected by DTI and temperamental traits assessed character in 42 healthy aged adults.
using temperament and character inventory (TCI) in
100 healthy individuals. The authors found increased However, no significant correlations between regional
WM FA associated with higher novelty‑seeking WM volumes and personality traits were reported, and
scores suggesting that macro‑ and micro‑structural only a trend of correlation between right cerebellar WM
characteristics of posterior vermis play a critical role volume and self‑transcendence was observed.
in novelty‑seeking behaviors. In a previous report,
the same research group suggested that the scores of To our knowledge, no other studies supported the
the four temperamental scales of TCI were positively association between affective temperaments, WMHs
associated with the volumes of cerebellar WM. [109] and suicidal risk. Table 1 summarizes the most relevant
Specifically, it has been suggested that novelty seeking evidence for the association between WM abnormalities

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