BackgroundUnderstanding how physical activity (PA) influences cognitive function in populations with cognitive impairments, such as dementia, is an increasingly studied topic yielding numerous published systematic reviews. In contrast, however, there appears to be less interest in examining associations between PA and cognition in cognitively healthy individuals. Therefore, the objective of this review was to evaluate and synthesize randomized controlled trial (RCT) studies that investigated the effects of both chronic and acute PA on working memory performance (WMP) in physically and cognitively healthy individuals.MethodsFollowing the preferred reporting items for systematic review and meta-analysis (PRISMA) guidelines, a systematic review of studies published between August 2009 and December 2016 was performed on RCTs investigating the effects of chronic and acute PA on WMP with healthy participants as the sample populations. Searches were conducted in Annual Reviews, ProQuest, PsycARTICLES, PsycINFO, PubMed, and Web of Science. Main inclusion criteria stipulated (1) healthy sample populations, (2) PA interventions, (3) WMP as an outcome, and (4) RCT designs. Descriptive statistics included cohort and intervention characteristics and a risk of bias assessment. Analytical statistics included meta-analyses and moderation analyses.ResultsFrom 7345 non-duplicates, 15 studies (eight chronic PA and seven acute PA studies) met the inclusion criteria and were evaluated. Overall, there was noticeable variance between both cohort and intervention characteristics. Sample populations ranged from primary school children to retirement community members with PA ranging from cycling to yoga. The majority of studies were characterized by “low” or “unclear” risk of selection, performance, detection, attrition, reporting, or other biases. Meta-analysis of chronic PA revealed a significant, small effect size while analysis of acute PA revealed a non-significant, trivial result. Age and intensity were significant moderators while allocation concealment, blinding, and intervention length were not.ConclusionsChronic PA can significantly improve WMP while acute PA cannot. The limiting factors for acute PA studies point to the diversity of working memory instruments utilized, unequal sample sizes between studies, and the sample age groups. Large-scale, high-quality RCTs are needed in order to provide generalizable and more powerful analysis between PA and WMP in a systematic approach.Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-017-0514-7) contains supplementary material, which is available to authorized users.

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Transthoracic echocardiography (TTE) is frequently utilized in the initial evaluation of cardioembolic stroke. However, the diagnostic utility of TTE is often operator-dependent, and in conjunction with anatomical limitations, there is a range of sensitivities reported in the literature specifically in the evaluation of nonbacterial thrombotic endocarditis (NBTE). Thus, relying on TTE findings to rule out NBTE in the setting of cardioembolic stroke evaluation can lead to misdiagnosis in the absence of confirmatory transesophageal echocardiography (TEE).We present a case of a 67-year-old female with a past medical history of hypertension, diabetes mellitus, human immunodeficiency virus (HIV), and recurrent ischemic strokes who was referred by her neurologist for TEE. Despite an initial TTE with a bubble study showing no evidence of intra-atrial septum, left ventricular thrombus, or any valvular pathology, there remained high suspicion of a cardioembolic source due to the bi-hemispheric presentation of the patient's previous strokes. Prior electrocardiography and cardiac event monitor showed normal sinus rhythm. Her TEE revealed a large, dense thrombus measuring 1.0 x 0.8 centimeters involving the anterior mitral valve leaflet with associated moderate mitral regurgitation. The patient was placed on systemic anticoagulation and discharged home with outpatient follow-up with cardiology. Our case highlights the diagnostic pitfalls of TTE use in the evaluation of cardioembolic stroke with a particular emphasis on NBTE in addition to discussing the rationale for followup TEE when TTE is otherwise unrevealing.