Key points are not available for this paper at this time.
Dear Editor, I read with great interest the recent article published in Nutrition Reviews, “Creatine and Cognition in Aging: A Systematic Review of Evidence in Older Adults” by Marshal et al.1 The topic is undoubtedly relevant, as dietary creatine has attracted increasing attention not only for its well-established effects on skeletal muscle–related outcomes,2–7 but also for its potential impact on brain health and cognitive functioning.8,9 However, I would like to raise several concerns regarding the methodological rigor of this review article and the interpretation of its findings by the authors, which, in my opinion, limit the validity of the conclusions presented. This review included 6 studies: 2 intervention trials (1 randomized controlled trial RCT10 and 1 short-duration crossover study11) and 4 observational cross-sectional studies12–15 based on dietary recall.1 The inclusion of both RCTs and cross-sectional studies poses a serious methodological challenge because these study types differ profoundly in design, purpose, and inferential capacity.16 While RCTs are experimental in nature and represent the gold standard for assessing causality,16 cross-sectional studies are descriptive “snapshots” that measure exposure and outcome simultaneously.
Marcus Vinicius Lúcio dos Santos Quaresma (Wed,) studied this question.