Divergent brain network connectivity in amyotrophic lateral sclerosis

Using resting state (RS) functional magnetic resonance imaging and independent component analysis, the integrity of brain networks related to cognition and behavior was investigated in 20 nondemented patients with amyotrophic lateral sclerosis (ALS). The association between RS functional connectivity and executive functions was assessed in 16 patients with neuropsychological assessment. ALS patients compared with control subjects showed a decreased connectivity of the right orbitofrontal cortex, and an enhanced connectivity of the left precuneus in the default mode network; a decreased connectivity of the left inferior frontal cortex, and an increased connectivity of the right angular gyrus in the right frontoparietal network; and an increased connectivity of the parietal cortex in the left frontoparietal network. The enhanced parietal connectivity was associated with the clinical and cognitive deficits of the patients. In ALS, an alteration of large-scale functional brain networks associated with cognition does occur, even in the absence of overt dementia. The increased parietal connectivity may have a role in an attempt to maintain cognitive efficiency in the presence of structural frontotemporal injury.