Exploring the relationship between physical activity, beta-amyloid and tau: A narrative review.

Several prospective cohort studies have reported an association between higher levels of physical activity and decreased risk of cognitive decline and dementia, years later. To support physical activity as a preventative measure against dementia, including Alzheimer's disease (AD; the most common form of dementia), evidence regarding the underlying mechanisms is vital. Here, we review previous work examining the role of physical activity in modulating levels of AD pathological hallmarks, beta-amyloid (Aβ) and tau (in the brain, cerebrospinal fluid and blood). Robust evidence from transgenic animal studies suggests that physical activity (voluntary wheel running) and exercise (forced wheel running) are implicated in lowering levels of brain Aβ and tau. Nevertheless, evidence from human studies, utilising measurements from positron emission tomography and cerebrospinal fluid biomarkers, is less consistent. Rigorous randomised controlled trials utilising long exercise interventions are vital to further understand the relationship between physical activity and Alzheimer's disease.