Individuals who receive chiropractic care often report improvement in cognitive performance, yet little is understood about how the improvements occur. In this study a secondary analysis of electroencephalography (EEG) data from a previous chiropractic randomized controlled trial was analyzed at three time points. The purpose of this study was to assess changes in brain communication patterns following a single chiropractic adjustment. Brain communication changes were measured using Phase Slope Index, a measure of the direction and magnitude of communication between two brain regions. Fourteen Brodmann areas were assessed that had either shown previous responses to chiropractic or were related to cognitive task performance. Similar to previous chiropractic research, the results for the adjustment group demonstrated changes within the brain in areas associated with executive function, attention, and spatial awareness. These included the prefrontal cortex and posterior cingulate cortex, with unique changes in the dorsal lateral prefrontal cortex. Contrary to expectations, changes similar to previous chiropractic research were also noted in the sham group; these included the somatosensory cortex and posterior cingulate, with a unique presentation in the visual association area. Both the adjustment and sham groups demonstrated changes in regions associated with cognitive task performance: anterior brain regions for the adjustment group and more posterior regions for the sham group. While the brain demonstrated different changes between the groups, more research is needed to delineate the effects of sham related factors such as touch from the adjustive force effects. Relative to time, few changes were noted between the baseline and post assessment, and in some instances the additional observation of the one-week time point demonstrated lack of sustained changes. Regional brain connectivity changes were most noted at the one-week time point. Overall, the results of this study suggest that a single session of chiropractic can change brain communication patterns, that those patterns are different from an applied sham adjustment, and that the changes occur over one-week. Further, additional insight was provided into the need for more research in the development of a sham adjustment protocol that accounts for individual complex elements of the chiropractic adjustment, such as touch.