Functional Connectivity Networks in Asymptomatic and Symptomatic DYT1 Carriers.

BACKGROUND: DYT1 mutation is characterized by focal to generalized dystonia and incomplete penetrance. To explore the complex perturbations in the different neural networks and the mutual interactions among them, we studied symptomatic and asymptomatic DTY1 mutation carriers by resting-state functional MRI. METHODS: A total of 7 symptomatic DYT1, 10 asymptomatic DYT1, and 26 healthy controls were considered. Resting-state functional MRI (Oxford Centre for Functional MRI of the Brain) [FMRIB] Software Library) (FSL) MELODIC, dual regression, (as a toolbox of FSL, with Nets is referred to "networks") (FSLNets) (http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/FSLNets) was performed on 9 resting-state neural networks. RESULTS: DYT1 mutation signature (symptomatic DYT1 and asymptomatic DYT1) was characterized by increased connectivity in the dorsal attention network and in the left fronto-parietal network. Functional correlates of symptomatic DYT1 patients (symptomatic DYT1 vs healthy controls) showed increased connectivity in the sensorimotor network. DISCUSSION: This study argues that DYT1 dystonia is a network disorder, with crucial nodes in sensory-motor integration of posterior parietal structures. A better characterization of cortical networks involved in dystonia is crucial for possible neurophysiological therapeutic interventions. © 2016 International Parkinson and Movement Disorder Society.

Looking for Measures of Disease Severity in the Frontotemporal Dementia Continuum.

Frontotemporal dementia (FTD) is characterized by executive dysfunctions, behavioral disturbances, language deficits and extrapyramidal symptoms. Frontotemporal lobar degeneration-modified Clinical Dementia Rating Scale (FTLD modified-CDR) has been proposed to measure disease severity in behavioral variant FTD (bvFTD). No tools of global disease severity are available in the other FTLD phenotypes [primary progressive aphasias (PPAs), progressive supranuclear palsy (PSP), and corticobasal syndrome (CBS)]. This would be strategic as outcome measures in clinical trials. To this aim, we evaluated the association between brain volume (voxel based morphometry) and available clinical scales in FTD. In 176 FTD patients (64 bvFTD, 40 PPAs, 32 PSP, 40 CBS), instrumental activities of daily living (ADLs), FTLD-modified CDR, Mini-Mental State Examination (MMSE), Frontal Behavioral Inventory (FBI), and Neuropsychiatry Inventory (NPI) were administered and MRI performed. Whole-brain linear correlation between each clinical rating scale and brain volume was performed. In bvFTD and PPAs, FTLD-modified CDR was associated with regional brain volume, thereby providing evidence for validity of the FTLD-modified CDR. In PSP, none of the clinical indicators were associated with regional brain volume. In CBS, ADLs and MMSE correlated with frontotemporal lower volume. Considering monogenic disease, FTLD-modified CDR was the best measure. In FTD continuum, different measures able to correlate with brain damage should be considered for the different clinical phenotypes or genetic traits.

Looking for Neuroimaging Markers in Frontotemporal Lobar Degeneration Clinical Trials: A Multi-Voxel Pattern Analysis Study in Granulin Disease.

In light of future pharmacological interventions, neuroimaging markers able to assess the response to treatment would be crucial. In Granulin (GRN) disease, preclinical data will prompt pharmacological trials in the future. Two main points need to be assessed: (1) to identify target regions in different disease stages and (2) to determine the most accurate functional and structural neuroimaging index to be used. To this aim, we have taken advantage of the multivariate approach of multi-voxel pattern analysis (MVPA) to explore the information of brain activity patterns in a cohort of GRN Thr272fs carriers at different disease stages (14 frontotemporal dementia (FTD) patients and 17 asymptomatic carriers) and a group of 33 healthy controls. We studied structural changes by voxel-based morphometry (VBM), functional connectivity by assessing salience, default mode, fronto-parietal, dorsal attentional, executive networks, and local connectivity by regional homogeneity, amplitude of low frequency fluctuations (ALFF), fractional ALFF (fALFF), degree centrality, and voxel-mirrored homotopic connectivity. In FTD patients with GRN mutation, the most predictive measure was VBM structural analysis, while in asymptomatic carriers the best predictor marker was the local connectivity measure (fALFF). Altogether, all indexes demonstrated fronto-temporo-parietal damage in GRN pathology, with widespread structural damage of fronto-parietal and temporal regions when disease is overt. MVPA could be of aid in identifying the most accurate neuroimaging marker for clinical trials. This approach was able to identify both the target region and the best neuroimaging approach, which would be specific in the different disease stages. Further studies are needed to simultaneously integrate multimodal indexes in a classifier able to trace the disease progression moving from preclinical to clinical stage of the disease.

Dyslexia susceptibility genes influence brain atrophy in frontotemporal dementia.

OBJECTIVE: In this study, we evaluated whether variations within genes specifically associated with dyslexia, namely KIAA0319, DCDC2, and CNTNAP2, were associated with greater damage of language-related regions in patients with frontotemporal dementia (FTD) and primary progressive aphasia (PPA) in particular. METHODS: A total of 118 patients with FTD, 84 with the behavioral variant of FTD (bvFTD) and 34 with PPA, underwent neuropsychological examination, genetic analyses, and brain MRI. KIAA0319 rs17243157 G/A, DCDC2 rs793842 A/G, and CNTNAP2 rs17236239 A/G genetic variations were assessed. Patients were grouped according to clinical phenotype and genotype status (GA/AA or GG). Gray matter (GM) and white matter (WM) differences were assessed by voxel-based morphometry and structural intercorrelation pattern analyses. RESULTS: Patients carrying KIAA0319 A* (GA or AA) showed greater GM and WM atrophy in the left middle and inferior temporal gyri, as compared with KIAA0319 GG (p < 0.001). The effect of KIAA0319 polymorphism was mainly reported in patients with PPA. In patients with PPA carrying at-risk polymorphism, temporal damage led to loss of interhemispheric and intrahemispheric GM and WM structural association. No effect of DCDC2 and CNTNAP2 was found. CONCLUSIONS: Genes involved in dyslexia susceptibility, such as KIAA0319, result in language network vulnerability in FTD, and in PPA in particular.