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The identification of biological and pathophysiological processes implicated in different forms of dementia is itself dependent on reliable descriptions of cognitive performance and capacities. However, traditional instruments are often unable to detect subtle declines in cognitive functions due to natural variation at the time of testing. Mobile technologies permit the repeated assessment of cognitive functions and may thereby provide more reliable descriptions of early cognitive difficulties that are inaccessible to clinic or hospital-based instruments. This assessment strategy is also able to characterize in real-time the dynamic associations between cognitive performance and specific daily life behaviors or activities. In a cohort of elderly rural residents, 60 individuals were administered neuropsychological and neuroimaging exams as well as a one-week period of electronic ambulatory monitoring of behavior, semantic memory performance, and daily life experiences. Whereas imaging markers were unrelated to traditional neuropsychological test scores, they were significantly associated with mobile assessments of semantic memory performance. Moreover, certain daily life activities such as reading or completing crossword puzzles were associated with increases in semantic memory performance over the subsequent hours of the same day. The revolution in mobile technologies provides unprecedented opportunities to overcome the barriers of time and context that characterize traditional hospital and clinical-based assessments. The combination of both novel and traditional methods should provide the best opportunity for identifying the earliest risk factors and biomarkers for Alzheimer's disease and other forms of dementia.

The MeDi appears to benefit brain health through preservation of structural connectivity. Potential mediation by a favorable impact on brain vasculature deserves further research.

Background: Several imaging studies have identified localized anatomical and functional brain changes in medicationoveruse headache (MOH). Objective: The objective of this article is to evaluate whole-brain functional connectivity at rest together with voxel-based morphometry in MOH patients, in comparison with episodic migraine (EM) patients and healthy controls (HCs). Methods: Anatomical MRI and resting-state functional MRI scans were obtained in MOH patients (n ¼ 17 and 9, respectively), EM patients (n ¼ 18 and 15, respectively) and HCs (n ¼ 17 and 17). SPM8 was used to analyze voxel-based morphometry and seed (left precuneus) to voxel connectivity data in the whole brain. Results: Functional connectivity at rest was altered in MOH patients. Connectivity was decreased between precuneus and regions of the default-mode network (frontal and parietal cortices), but increased between precuneus and hippocampal/ temporal areas. These functional modifications were not accompanied by significant gross morphological changes. Furthermore, connectivity between precuneus and frontal areas in MOH was negatively correlated with migraine duration and positively correlated with self-evaluation of medication dependence. Gray matter volumes of frontal regions, precuneus and hippocampus were also negatively related to migraine duration. Functional connectivity within the defaultmode network appeared to predict anxiety scores of MOH patients while gray matter volumes in this network predicted their depression scores. Conclusions: Our data suggest that MOH is associated with functional alterations within intrinsic brain networks rather than with macrostructural changes. They also support the view that dependence-related processes might play a prominent role in its development and maintenance.

High cognitive demand causes beneficial cerebral recruitment failure, leading to cognitive impairment in patients with RRMS. Functional compensatory mechanisms preserving good cognitive performances operate by a new cerebral strategy involving medial prefrontal regions recruitment, instead of cerebellar regions seen in controls. This new recruitment is diffuse tissue damage-dependent. Missing cerebellar involvement argues for an inability to generate proficient cognitive automation processes in patients, directly leading to recruitment of high-level decision-making areas. Recurrent mobilization of cortical regions could explain the limiting effect of the cognitive load on the cognitive compensatory phenomena in patients with MS.

These results suggest that a dysfunction of DMN functional connectivity involved in emotional control is associated with the severity of poststroke depression. Further studies are necessary to determine the mechanisms of this functional impairment.

Microstructural changes of White Matter (WM) associated with aging have been widely described through Diffusion Tensor Imaging (DTI) parameters. In parallel, White Matter Hyperintensities (WMH) as observed on a T2-weighted MRI are extremely common in older individuals. However, few studies have investigated both phenomena conjointly. The present study investigates aging effects on DTI parameters in absence and in presence of WMH. Diffusion maps were constructed based on 21 directions DTI scans of young adults (n = 19, mean age = 33 SD = 7.4) and two age-matched groups of older adults, one presenting low-level-WMH (n = 20, mean age = 78, SD = 3.2) and one presenting high-level-WMH (n = 20, mean age = 79, SD = 5.4). Older subjects with low-level-WMH presented modifications of DTI parameters in comparison to younger subjects, fitting with the DTI pattern classically described in aging, i.e., Fractional Anisotropy (FA) decrease/Radial Diffusivity (RD) increase. Furthermore, older subjects with high-level-WMH showed higher DTI modifications in Normal Appearing White Matter (NAWM) in comparison to those with low-level-WMH. Finally, in older subjects with high-level-WMH, FA, and RD values of NAWM were associated with to WMH burden. Therefore, our findings suggest that DTI modifications and the presence of WMH would be two inter-dependent processes but occurring within different temporal windows. DTI changes would reflect the early phase of white matter changes and WMH would appear as a consequence of those changes.