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BACKGROUND: Research in modifiable behaviors, like exercise, on risk for dementia is increasing. Although many studies focus on older adults, brain pathology for Alzheimer's Disease can begin in middle age, suggesting an ideal target for intervention. METHODS: We conducted a systematic review from exercise intervention studies on cognitive function among healthy, middle-aged participants (45-65). We searched multiple databases (PubMed, PsycINFO, MEDLINE, Cochrane Central Register of Controlled Trials, Google Scholar) for studies using standard, validated, neuropsychological measures following either single- or multi-session interventions in cognitively-unimpaired, middle-aged adults. RESULTS: We identified 13 eligible studies. There was notable heterogeneity across studies, with varying design, measures, interventions, and results. Results from single-session studies showed improvement in response inhibition, while results for cognitive flexibility were mixed. No significant changes were found on measures of attention, working memory, or processing speed. Results from multi-session studies were more varied. Verbal memory was found to improve while performance on tests of attention and working memory, processing speed, and executive function were mixed. CONCLUSION: Importantly, for both single-session and multi-session studies, there was no standard set of neuropsychological tests administered, making it more difficult to synthesize the findings into a single narrative. We end with a discussion on future directions and implementation.
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PURPOSE: To characterize the impact of slowed processing speed on the efficiency of broader cognitive function in temporal lobe epilepsy (TLE). METHODS: Participants included 100 patients with TLE and 89 healthy controls (mean ages 36.8 and 33.6, respectively) administered a neuropsychological battery consisting of 15 cognitive metrics. Confirmatory factor analysis using structural equation modeling (SEM) latent variable modeling demonstrated a cognitive structure representing the domains of verbal intelligence, immediate memory, delayed memory, executive function, working memory, and processing speed. Furthermore, the latent variable measurement model determined the direct and indirect relationships of verbal intelligence and processing speed with immediate memory, delayed memory, executive function, and working memory. RESULTS: Following SEM of hypothesized structural models, the results demonstrated that, among controls, intelligence had a direct and unmediated (by processing speed) relationship with all identified cognitive domains. In contrast, among participants with TLE, processing speed mediated the relationship between verbal intelligence and performance across all cognitive domains. CONCLUSION: Slowing of cognitive/psychomotor processing speed appears to play a critical mediating role in the broader cognitive status of participants with TLE and may serve as a target through which to attempt to exert a broad positive impact on neuropsychological status.
