Physical activity has received substantial research attention due to its beneficial impact on cognition in ageing, particularly via the action of brain-derived neurotrophic factor (BDNF). It is well established that physical activity can elevate circulating levels of BDNF, and that BDNF has neurotrophic, neuroprotective and cognitively beneficial properties. Yet, practical implementation of this knowledge is limited by a lack of clarity on context and dose-effect. Against a shifting backdrop of gradually diminishing physical and cognitive capacity in normal ageing, the type, intensity, and duration of physical activity required to elicit elevations in BDNF, and more importantly, the magnitude of BDNF elevation required for detectable neuroprotection remains poorly characterised. The purpose of this review is to provide an overview of the association between physical activity, BDNF, and cognition, with a focus on clarifying the magnitude of these effects in the context of normative ageing. We discuss the implications of the available evidence for the design of physical activity interventions intended to promote healthy cognitive ageing.

身体活动对衰老认知的有益影响，尤其是通过脑源性神经营养因子（BDNF）的作用，已引起了广泛的研究关注。众所周知，体育锻炼可以提高BDNF的循环水平，并且BDNF具有神经营养，神经保护和认知有益的特性。然而，由于上下文和剂量效应的缺乏清晰性，限制了该知识的实际实施。在正常衰老过程中逐渐减弱的身体和认知能力的变化背景下，引起BDNF升高所需的体力活动的类型，强度和持续时间，更重要的是，可检测的神经保护所需的BDNF升高幅度仍然很差。这篇综述的目的是概述身体活动，BDNF和认知之间的关联，重点是在规范老龄化的背景下阐明这些影响的程度。我们讨论了现有证据对旨在促进健康认知老化的体育锻炼干预措施的设计意义。