Evaluating multicenter DTI data in Huntington's disease on site specific effects:an ex post facto approach

Purpose: Assessment of the feasibility to average diffusion tensor imaging (DTI) metrics of MRI data acquired in the course of a multicenter study.Materials and methods: Sixty-one early stage Huntington's disease patients and forty healthy controls were studied using four different MR scanners at four European sites with acquisition protocols as close as possible to a given standard protocol. The potential and feasibility of averaging data acquired at different sites was evaluated quantitatively by region-of-interest (ROI) based statistical comparisons of coefficients of variation (CV) across centers, as well as by testing for significant group-by-center differences on averaged fractionalanisotropy (FA) values between patients and controls. In addition, a whole-brain based statistical between-group comparison was performed using FA maps.Results: The ex post facto statistical evaluation of CV and FA-values in a priori defined ROIs showed no differences between sites above chance indicating that data were not systematically biased by center specific factors.Conclusion: Averaging FA-maps from DTI data acquired at different study sites and different MR scanner types does not appear to be systematically biased. A suitable recipe for testing on the possibility to pool multicenter DTI data is provided to permit averaging of DTI-derived metrics to differentiate patients from healthy controls at a larger scale

The neuropsychology of first impressions : evidence from Huntington’s disease

Impairments of emotion recognition have been widely documented in Huntington's disease (HD), but little is known concerning how these relate to other aspects of social cognition, including first impressions of traits such as trustworthiness and dominance. Here, we introduce a novel and sensitive method to investigate the ability to evaluate trustworthiness and dominance from facial appearance, with control tasks measuring ability to perceive differences between comparable stimuli. We used this new method together with standard tests of face perception to investigate social cognition in HD. We found that a subgroup of people with HD was impaired at perceiving trustworthiness and dominance, and that perceiving trustworthiness and dominance were correlated with impaired facial expression recognition. In addition, we used diffusion tensor imaging (DTI) to provisionally identify candidate brain regions associated with social cognition by contrasting regional functional anisotropy (FA) measures between subgroups of HD participants showing normal or impaired perception of trustworthiness and dominance, and by correlating these regional brain abnormalities with behavioural performance on tests of emotion recognition. In this way we show for the first time alterations in perception of trustworthiness and dominance in people with HD and link these to regions which may map the boundaries of the social brain. The pattern of breakdown seen in this neurodegenerative disease can thus be used to explore potential inter-relationships between different components of social cognition.PostprintPeer reviewe

The neuroanatomy of sub-threshold depressive symptoms in Huntington's disease: a combined DTI and VBM study

Background: Depressive symptoms are prominent psychopathological features of Huntington’s disease (HD), impacting negatively on social functioning and well-being.Methods: We compared the frequencies of a history of depression, previous suicide attempts and current sub-threshold depression between 61 early stage HD participants and 40 matched controls. The HD group was then split based on the overall HD group’s median HADS-depression score into a group of 30 non-depressed participants (mean 0.8, SD 0.7), and a group of 31 participants with sub-threshold depressive symptoms (mean 7.3, SD 3.5 to explore the neuroanatomy underlying sub-threshold depressive symptoms in HD using Voxel-Based Morphometry (VBM) and Diffusion Tensor Imaging (DTI). Results: Frequencies of history of depression, previous suicide attempts, or current sub-threshold depressive symptoms were higher in HD than in controls. The severity of current depressive symptoms was also higher in HD, but not associated with the severity of HD motor signs or disease burden. Compared to the non-depressed HD group DTI revealed lower fractional anisotropy (FA) values in the frontal cortex, ACC, insula and cerebellum of the HD group with sub-threshold depressive symptoms. In contrast, VBM measures were similar in both HD groups. A history of depression, the severity of HD motor signs, or disease burden did not correlate with FA values of these regions.Conclusions: Current sub-threshold depressive symptoms in early HD are associated with microstructural changes - without concomitant brain volume loss - in brain regions known to be involved in Major Depressive Disorder, but not those typically associated with HD pathology. <br/