Cognitive Decline and White Matter Integrity Degradation in Myotonic Dystrophy Type I.

BACKGROUND AND PURPOSE: Myotonic Dystrophy Type I (DM1) is a neurodegenerative, genetic, and multisystemic disorder with a large variety of symptoms due to a CTG trinucleotide expansion located on Dystrophia Myotonica Protein Kinase (DMPK) gene. Previous reports have shown cognitive deterioration in these patients. Given that white matter (WM) degradation has also been reported in DM1 patients, here we explored if alterations in the cognitive profile of DM1 patients could be related to the deterioration of WM. METHODS: A total of 22 classic DM1 patients with age range (18-56 years) and 22 matched healthy control subjects were neuropsychological evaluated by the Cambridge Neuropsychological Test Automated (CANTAB). Patients were evaluated with the Muscular Impairment Rating Scale (MIRS). We then evaluated the cerebral WM integrity using the Fractional Anisotropy (FA) index obtained from the Diffusion Tensor Imaging (DTI) data acquired with a 3T MR scanner. RESULTS: DM1 patients showed generalized reduction of WM integrity across the brain. Similarly, patients' neuropsychological evaluation showed significant deficits in memory and problem-solving tasks. Correlation analyses showed a significant correlation between FA deterioration at frontal, temporomedial, and parietal lobes and delayed matched to sample deficits. CONCLUSIONS: Our results suggest that despite the pervasive WM integrity loss in DM1 disorder, specific memory impairments can be associated to discreet areas of WM deterioration in these patients.

Prefrontal cortical thickness and clinical characteristics of long-term treatment response to valproate in bipolar disorder.

Valproate compositions are frequently used to treat bipolar disorder (BD); however, 87% of patients do not report full response in the long-term. There is scarce information about the clinical features and brain structural characteristics of long-term treatment response (LTTR) to this medication. In this study, we aim to evaluate the clinical characteristics and prefrontal cortical thickness (CT) of LTTR to valproate in BD. We evaluated 30 BD outpatients on valproate treatment, and 20 controls with a 3T T1-weighted 3D brain scan and Alda's scale for LTTR. An analysis of covariance was used to evaluate CT measures and a logistic regression was conducted to predict the full response (FR) using clinical features and CT measures. Patients with an insufficient response (IR) reported thinner right frontal eye fields, anterior and dorsolateral prefrontal cortexes compared with controls. FR patients presented thicker right dorsolateral prefrontal cortex than IR and no differences with controls. Patients with mixed features presented increased odds of achieving FR, while CT measures reported non-significant results. This is the first study to report mixed features as a clinical predictor of valproate LTTR. Our findings also suggest better preservation of the right prefrontal cortex of subjects with FR to valproate.

Extrastriatal degeneration correlates with deficits in the motor domain subscales of the UHDRS.

INTRODUCTION: Striatal degeneration has significant behavioral effects in patients with Huntington's disease (HD). However, there is scant evidence of the possible contribution of extrastriatal regions to the motor alterations assessed within the different domains of the Unified Huntington's Disease Rating Scale (UHDRS). OBJECTIVE: Analyze if extrastriatal grey matter decrease in patients with HD correlates with motor performance assessed with the UHDRS and its different domains. METHOD: Twenty-two molecular diagnosed patients with incipient HD, and twenty-two control participants matched for sex and age participated in this study. Voxel-based morphometry (VBM) analyses were done to identify grey matter decrease in the HD patients, and its relationship with the motor deterioration measured with the UHDRS motor scale. To further explore this relationship, a principal component analysis (PCA) was done on the UHDRS domains scores. Then the average of each component was used as a covariate in a VBM analysis. Finally, individual sub-scores from each domain were also tested for correlations with the VBM results. RESULTS: In addition to the striatal degeneration, the VBM analysis showed significant negative correlations between the global UHDRS scores and the cerebellum, insula and precuneus atrophy. The UHDRS PCA showed component-related negative correlations suggesting a specific impact of individual degnerations. Further analyses with the individual sub-scores showed more specific corelations, including: chorea, with right caudate and left posterior cingulate gyrus; ocular pursuit, with left precentral gyrus, left superior temporal gyrus, cerebellum culmen and right temporal lobe. Saccadic movements with left postcentral gyrus and left middle occipital gyrus. CONCLUSION: In the early stages of HD, it is possible to find correlations between behavioral alterations as measured with the UHDRS motor domains, and extrastriatal regions, including specific areas of the cerebellum, and insular, parietal and frontal cortices. These areas could contribute to the HD related impairments along with the classical deficits associated with the striatal degeneration.