6.27 VA Reading - Segobin 2015 HBM

Segobin S, Ritz L, Lannuzel C, Boudehent C, Vabret F, Eustache F, Beaunieux H, Pitel AL (2015). Integrity of White Matter Microstructure in Alcoholics With and Without Korsakoff's Syndrome. Human Brain Mapping; in progress.

Results: UA(uncomplicated alcoholism) v.s. HC (healthy control)

• Nonparametric permutation tests
• Reported value: T_max, k, n^2
• Lower FA values found in: corpus callosum, anterior limb of the internal capsule, anterior corona radiata, fornix, cingulum, middle cerebellar peduncle, superior cerebellar peduncle (I still don't know where these are!)

KS (Korsakoff's Syndrome) v.s. HC

• Similar to that between UA and HC
• FA was lower in KS
• T and k values are higher
• Regions: corpus callosum, anterior corona radiata, anterior limb of the internal capsule, cingulum, fornix, middle cerebellar peduncle, superior cerebellar peduncle

UA v.s. KS

• Differences mainly found in the corpus callosum and anterior corona radiata
• No gender effect
• In control group, Mann-Whitney U test shows differences between men and women for the cingulum

 Discussion The use of a voxel-based approach may have enabled the observation of the latter finding since a ROI approach, which would average the FA values within a region defined a priori, would not reveal any localized impairments within the fibers. Thus, WM abnormalities in the middle and superior cerebellar peduncles revealed by TBSS suggest that disruption may be more localized than spread-throughout in those fibers.
The study provides consolidating evidence of WM disruptions in the PC that is linked to episodic memory deficits and therefore amnesia [Kessels and Kopelman, 2012 for review). Damaged FCC has been hypothesized to be involved in working memory and executive dysfunction in KS [Wijnia and Goossensen, 2010].
Still difficult to evaluate the cascade of events (neurotransmission dysfunction - local or global network disruption - cellular damage/atrophy) that effectively governs the pathophysiological mechanism of KS when using a cross-sectional paradigm. Longitudinal studies are required to concretely establish this mechanism.
The abnormalities in the microstructural integrity of the corpus callosum have also been hypothesized to be due to thiamine deficiency as observed in a study with rats [He et al., 2007].
Significance: The use of DTI may be particularly relevant as a structural biomarker toward the early identification of UA patients at risk of developing KS. The early identification is important for clinicians to apply the correct and optimal treatment with the aim of preventing severe, debilitating and irreversible neurological complications.
Multi-modalneuroimaging, combined with biological and neuropsychological analyses will enable researchers to explore the characteristics of these clinical forms in terms of detailed microstructure, regional volume, function, enzyme metabolism, and cognitive deficits.