Fitness, aging and neurocognitive function
Introduction
The SPARK workshop focused on the relationship among obesity, diabetes, mood and cognition. Cleary, one important factor that relates to each of these constructs is physical activity and exercise. Lack of physical activity has been implicated in various health conditions including diabetes, cardiovascular disease, cancer, and osteoarthritis [14]. Increased physical activity reduces the risk associated with these diseases. Although less well-known, there is also an emerging body of literature that has found moderate to strong associations between physical activity and cognition, mood and human brain function, particularly in a group of individuals vulnerable to the loss of independence and cognitive decline, that is, older adults.
In the present paper we focus on the literature that has examined the relationship between physical activity and exercise on human cognition, brain structure and brain function. Specifically, we will examine the question of whether exercise can reduce age-related decline in cognition and decrease the risk for age-associated neurological disorders such as Alzheimer's disease. Rather than providing a thorough historical overview of this rapidly expanding literature we will concentrate on the expansion in our knowledge of the relationship among exercise, cognition and brain that has taken place over the past decade or so. To this end we will review both prospective and retrospective epidemiological studies as well as randomized clinical trials of exercise effects on human cognition, brain structure and brain function.
However, before focusing on the human literature we believe that it is important to provide a context for these studies, which largely derives from experiments with non-human animals. The examination of exercise effects in animals represents an expansion of a research program that has focused on the influence of complex environments on the brains of rodents. Given that living in complex environments entails increased physical as well as cognitive challenges, researchers began to decompose the influence of different aspects of these environments on brain structure and function. For example, Black et al. [5] compared the influence of wheel running with motor skills training on the brain function of older rats. Interestingly, the wheel running group developed a higher density of capillaries in the cerebellum than the animals trained on motor skills or a group of inactive controls. On the other hand, the animals in the motor skill group showed a larger increase in synapses in the cerebellum than the other two groups. Other studies have shown similar effects of treadmill exercise on the vasculature in the motor cortex of middle aged monkeys [19].
Exercise training in aging animals has also been shown to increase levels of key neurochemicals that improve plasticity and neuronal survival, such as brain-derived neurotrophin factor (BDNF) and insulin-like growth factor 1 (IGF-1), serotonin, as well as reduced corticosteroid levels [4], [6], [12]. There have also been a number of recent demonstrations of enhanced learning and memory and neurogenesis with exercise training [21], [22]. Finally, voluntary exercise has been found to decrease amyloid load in a transgenic mouse model of Alzheimer's disease [2]. Such data provide a promising context in which to examine the influence of fitness training on human cognition, brain structure and function.
Section snippets
Epidemiological studies of fitness effects on human cognition
A number of recent prospective studies with fairly large numbers of older participants have examined the relationship between measures of physical activity and cognition. For example, Yaffe et al. [23] reported a study of 5925 high functioning community dwelling women (>65 years of age), who were characterized in terms of the number of blocks that they walked per week. The central question was whether higher levels of activity, particularly the number of blocks walked per week, would serve a
Fitness training effects on cognition and brain
Human fitness training studies conducted over the past several decades have produced a varied pattern of results. Some studies find a positive relationship between fitness training and cognition while other studies fail to observe such a relationship. There are a multitude of potential reasons for this mixed pattern of results including the use of different physical training and assessment protocols, different cognitive assessments, and generally small sample sizes. To increase the power to
Conclusions and future directions
The human behavioral and brain data discussed above suggest that fitness training holds great promise as a neuroprotective intervention during the course of the adult lifespan. The human data also are compatible with non-human animal studies of fitness training effects on performance, brain function, and brain structure.
However, there clearly are important questions that remain to be answered. For example, it is still unclear as to the dose response relationship among mode, duration and
Conflict of interest
None of the authors have any conflict of interest to report. The study was conducted consistent with ethical principles.
Acknowledgements
We would like to thank the National Institute on Aging (AG25667 and AG25032) and the Institute for the Study of Aging for their support of our research.
References (23)
- et al.
Exercise: a behavioral intervention to enhance brain health and plasticity
Trends Neurosci
(2002) - et al.
Synaptic plasticity in cortical systems
Curr Opin Neurobiol
(1999) - et al.
Does active leisure protect cognition? Evidence from a national birth cohort
Soc Sci Med
(2003) - et al.
Walking and dementia in physically capable elderly men
J Am Med Assoc
(2004) - et al.
Voluntary exercise decreases amyloid in a transgenic model of Alzheimer's disease
J Neurosci
(2005) - et al.
A longitudinal study of cardiorespiratory fitness and cognitive function in healthy older adults
J Am Geriatr Soc
(2003) - et al.
Estrogen and exercise interact to regulate brain-derived neurotropic factor mRNA and protein expression in the hippocampus
Eur J Neurosci
(2001) - et al.
Learning causes synaptogenesis, whereas motor activity causes angiogenesis, in cerebellar cortex of adult rats
Proc Natl Acad Sci
(1990) - et al.
Circulating insulin-like growth factor 1 mediates the protective effects of physical exercise against brain insults of different etiology and anatomy
J Neurosci
(2001) - et al.
Aerobic fitness reduces brain tissue loss in aging humans
J Geron: Med Sci
(2003)
Cardiovascular fitness, cortical plasticity, and aging
Proc Natl Acad Sci
Cited by (178)
Cardiorespiratory fitness and prefrontal cortex oxygenation during Stroop task in older males
2021, Physiology and BehaviorCitation Excerpt :Several reviews suggest that cardiorespiratory fitness (CRF) may protect the brain against the typical effects of aging as well as the cumulative effects of age-associated health problems [1–3].
Exergames: What they are and how they can be used to successful aging?
2021, Assessments, Treatments and Modeling in Aging and Neurological Disease: The Neuroscience of AgingObese but Fit: The Benefits of Fitness on Cognition in Obese Older Adults
2020, Canadian Journal of Cardiology