Effects of physical activities on dementia‐related biomarkers: A systematic review of randomized controlled trials

Abstract

Introduction Physical activities (PA) may lead to improved cognition in mild cognitive impairment (MCI), Alzheimer's disease (AD), and dementia. The mechanisms mediating potential PA effects are unknown. Assessment of PA effects on relevant biomarkers may provide insights into mechanisms underlying potential PA effects on cognition. Methods We systematically reviewed randomized controlled trials (RCTs) that studied PA effects on biomarkers in MCI, AD, and dementia populations. We examined whether biological mechanisms were hypothesized to explain associations among PA, biomarkers, and cognitive functions. We used the PubMed database and searched for RCTs with PA until October 31, 2019. Results Of 653 studies examining changes in biomarkers in PA trials, 18 studies met inclusion criteria for the present review. Some studies found favorable effects of PA on neurotrophic and inflammatory biomarkers. AD pathological markers were rarely investigated, with inconclusive results. Most studies were relatively small in sample size, of limited duration, and not all studies compared the changes in biomarkers between the control and experimental groups. Discussion There is only limited use of potentially informative biomarkers in PA trials for MCI, AD, and dementia. Most studies did not examine the role of biomarkers to study associations between PA and cognitive functions in their analyses. Several potential biomarkers remain uninvestigated. Careful use of biomarkers may clarify mechanisms underlying PA effects on cognition. Our review serves as a useful resource for developing future PA RCTs aimed at improving cognitive functions in MCI, AD, and dementias.

Accelerometer‐measured physical activity and sitting with incident mild cognitive impairment or probable dementia among older women

“…These mechanisms could have contributed to the null associations for ST and MSBD in the present study. Few studies have examined the associations of PA and SB with early AD pathologic markers such as amyloid‐beta species and tau protein, and findings are equivocal 56 . Additional research is warranted to better understand how PA and SB influence the heterogenous mechanisms involved in the pathogenesis of MCI, dementia, and dementia subtypes.…”

Calanus Oil Supplementation Does Not Further Improve Short-Term Memory or Brain-Derived Neurotrophic Factor in Older Women Who Underwent Exercise Training

“…This finding is in line with study of Coelho-Júnior et al, who also observed cognitive function improvements without any positive changes in BDNF, 44 while other studies showed BDNF improvements in conjunction with improvements in physical fitness and cognitive function. 2 , 16 One possible rationale for these contradictory findings is the baseline cognitive characteristics of the subjects. For example, a previous study noted that increases of BDNF in response to an exercise program occurred in individuals with mild cognitive impairment, 15 whereas the subjects in our study did not have any cognitive impairments.…”

“…13 Although many factors likely contribute to the positive effects of exercise on cognitive function, two of the most important factors include increased blood flow to the brain (providing the necessary nutrients 14 and increased neurotrophic factors in response to physical activity (especially brain-derived neurotrophic factor (BDNF))). 1,15,16 BDNF is a polypeptide growth factor that is expressed in the central nervous system and is considered to be extremely important for learning and forming memories. It plays a crucial role in regulating synaptic plasticity, and it also plays a role in neurogenesis and neuronal survival.…”

The Internet-Based Conversational Engagement Clinical Trial (I-CONECT) in Socially Isolated Adults 75+ Years Old: Randomized Controlled Trial Protocol and COVID-19 Related Study Modifications

“…Fifth, exploratory analyses on changes in speech characteristics could yield promising behavioral markers of early cognitive decline, responding to the urgent need to identify ecologically valid outcomes sensitive to trials effects in the dementia research field ( 3 ). Finally, while exercise-based interventions often aim to examine the underlying biological mechanisms of efficacy ( 57 ), how and why social interaction affects cognition is yet to be discovered. We will use baseline characteristics of brain structures and connectivity to investigate who gains most in addition to the intervention efficacy (pre-post changes).…”