Abstract in studying the relationship between exercise

Abstract

 

The effect of exercise on
physical health is well documented. What is less studied, but by no means less
significant, is the relationship between exercise, cognition and neurological
health. Physical exercise has been found to improve executive function through
the stimulation of the anterior cingulate cortex. Additionally, physical
exercise causes cognitive processing during stimulus encoding to occur faster. This
is due to larger amplitude and shorter latency P300 components. The
relationship between exercise and cognition could be used as a treatment for
Alzheimer’s disease and Schizophrenia. In Alzheimer’s disease an increased
level of physical fitness has been found to reduce the amyloid load, decrease ??
deposits, up regulate the levels of Nepresprin and increase hippocampal
functioning due to an increase in the secretion of brain-derived neurotropic
factor. In patients with Schizophrenia exercise has increased the hippocampal
volume, changed the cortical thickness and increased secretion of brain-derived
neurotropic factor. The relationship between aerobic fitness and academic
performance in children was also examined, with the trend being that children
who are more aerobically fit score higher on mathematics and reading tests. It
is postulated that the frontopariteal network is linked to both cognition and
exercise. When used in conjunction with other forms of treatment exercise has
the capacity to improve the symptoms of various neurological diseases, and
healthcare policy should be updated to reflect this.

 

Introduction

 

We all know that exercise is
key to a healthy lifestyle, but could exercise improve your neurological health?
In recent years, there has been an increase of interest in studying the relationship
between exercise and cognition. This relationship becomes increasingly important
when studied in conjunction with a variety of neurological disorders. The
potential for exercise to reduce the risk of developing age associated neurodegenerative
disorders, such as Alzheimer’s disease and vascular dementia (Paillard 2015), is an important area. It has also
been shown that regular exercise can help improve the clinical symptoms of
patients with psychological conditions such as Schizophrenia (Nuechterlein 2016). The effect of exercise on the cognition
and academic performance of children is also an interesting area of research,
many school teachers will tell you that children perform better academically
after a break from their schoolwork, but is there a scientific explanation for
this? Whilst the molecular mechanisms for these effects are relatively unknown,
some progress has been made in understanding the structural alterations to the
brain during exercise that have an effect on cognition.

 

Effects
of exercise on the human brain

 

Physical exercise has the
capacity to improve cognition, specially, it has been found to improve
executive control processes.  Therefore
it follows that brain structures that are involved in executive control are
likely to be altered by physical exercise. The anterior cingulate cortex (ACC),
which is a part of the limbic system, is one such region. Physical activity has
a significant effect on the ACC. Neuroimaging studies that focused on the
effect of changes in aerobic fitness and the ACC found that adults that had partaken
in an exercise program showed a decrease in behavioral conflict when performing
a task that required differing levels of executive control, when compared
against untrained participants. This supports the view that higher levels of physical
activity are associated with increased top down control, mediated through the
ACC, resulting in increased performance of tasks that require high levels of
executive control. (Hillman 2008).

 

Furthermore, aerobic fitness
also appears to have a relationship with the P3 component. The P3 component is
thought to be generated by a network of neural structures (including the ACC) that
has a role in cognition. Specifically these neural structures have roles in
stimulus updating and memory processing. (Polich
2004). Multiple studies have found that larger
amplitude and shorter latency P3s are found in individuals with

 

 

higher levels of aerobic
fitness. This suggests, that a high level of aerobic fitness is beneficial in cognitive
processing. In particular, processing that is involved in the allocation of attentional
resources and faster cognitive processing during stimulus encoding (Hillman 2008).

 

Alzheimer’s
disease and exercise

 

By
2050 the number of people living with Alzheimer’s disease (AD) in the United
States is projected to increase by 10million (Alzheimer’s
A 2015). This is a trend that is reflected worldwide, partly due to the
fact that people are living longer, emphasizing an already pressing need to understand and develop: novel treatments,
preventative measures and changes in healthcare policy for AD. Encouraging
patients who are likely to develop AD or other age associated neurodegenerative
disorders to engage in regular physical exercise could be a way of reducing their
risk of developing these diseases. This is because physical exercise has the
capacity to prevent age related cognitive decline (Bhreer
2013). It has been shown that as you get older, if you increase (or
maintain) your cognitive function you reduce the risk for devolving age
associated neurodegenerative disorders (Hilman). Highlighting
a use for so called “prescribed exercise” as a preventative
measure to lower the risk of developing AD.

 

The aggregation of Amyloid ?-peptide (??) plaques in
cerebellum is a key event in AD Pathogensis (Fig one). The rest of the diseases
processes, including TAU tangle formation, is a result of an imbalance of ??
production and clearance. (Hardy 2002). It has
been shown in animal models that regular exercise reduces the amyloid load (Adlard 2005). A 2005 study in mice found that
regular voluntary exercise significantly decreases the ?? load, and that
exercise could be a simple behavioral change to prevent or slow the development
of AD. Another study, again in mouse models, shows that an increase in exercise
leads to a decrease in cerebral ?? peptides and amyloid deposits in vivio. Additionally,
in this study the animals that had increased levels of exercise also showed
differences in gene expression. For example, the activity of Neprilysin (NEP),  a compound that degrades amyloid, is up
regulated in the brains of these mice (Karsten 2005).

 

In addition to accumulation of
??, AD causes changes in the brain structure- such as loss of cortical neurons
and loss of connections between brain systems (Dennis
2014). Additionally in AD, there is severe atrophy in the hippocampus.
The hippocampus is involved in episodic memory, which can be defined as the
ability to recall memory’s from ones past in context (La
Joie 2014). Physical exercise has the capacity to improve hippocampal function;
this is done by the increase of secretion of a molecule known as BDNF (brain-derived
neurotropic factor) during exercise (Intlekofer 2013). BDNF, along with additional
growth factors, promotes the processes of neurogenesis, angiogenesis and
synaptic plasticity. Physical activity has also been shown to preserve
hippocampal volume in elderly people with a high genetic risk of developing AD (Smith 2014).

 

Whilst this is an emerging
area of research, it highlights the potential for exercise to improve the cognition,
and potentially reduce the risk of developing AD. Therefore, encouraging people
who have a high risk of developing AD is something that should be considered in
Healthcare policy.

 

 

Exercise
and Schizophrenia

 

Schizophrenia
is a psychological condition which affects 1 in 100
people. The clinical symptoms of Schizophrenia include hallucinations,
delusions and disorganized behavior. Cognitive impairment is another symptom of
schizophrenia, specifically in executive function (Elliot
2003). This makes behaviors such as planning and reasoning difficult,
reducing the patient’s quality of life. As exercise has previously been shown
to improve cognition (and specifically executive function) in healthy individuals
it stands to reason that exercise may have the capacity to improve the
cognition in individuals with Schizophrenia.

 

The use of exercise as a form of treatment for individuals
with Schizophrenia becomes increasingly important when you consider that, for
many patients, cognitive behavioral therapy and Pharmacotherapy have already
been tried, and both may have unpleasant side effects making the treatment
somewhat redundant (Revvel 2015). Physical
exercise presents itself as a novel area to treat some of the symptoms of
Schizophrenia. In patients with Schizophrenia the Hippocampal volume is lowered
(Fig 2). Whilst antipsychotic medications do not have an effect on hippocampal
volume, exercise is known to increase it (Pajonk 2010).
Exercise also causes an increase in acetylcholine in the cerebral cortex,
increasing neural transmission and activity. The cumulative effect of exercise
has shown to demonstrate significant physiological changes in patients with
Schizophrenia. Specifically, changes in hippocampal volume, cortical thickness
and increased serum brain-derived neurotropic factor. (Subramaniapillai, M 2016).
Furthermore, individuals with Szchizoprenia have
lowered levels of the presynaptic proteins SNAP-25 and complexin I and II, leading
to increased levels of cognitive impairment. Exercise may induce changes in the
plasticity of synaptic proteins in the hippocampus thus improving cognitive
function (Pajonk 2010). Additionally, a
recent study found that in first episode patients promoting exercise as well as
cognitive training could promote recovery. Showing that exercise can be used
along side cognitive training, to boost its effects in reducing symptoms whilst
also improving social interaction. (Ventura 2017).  

 

 

Exercise
and academic performance in school aged children

 

Most teachers will tell you
that children are better behaved after they spend break time outside running
around. What might be more surprising to learn is that, statistically, children
who engaged in regular aerobic exercise have higher levels of academic
achievement that their sedate counterparts (Kim 2003). Many countries have Removed Physical
Education from their curriculum in an effort to focus more on standardized
testing and indeed, increase academic performance. However, recent studies have
shown that this actually has the inverse effect. Aerobic fitness has a positive
correlation to academic achievement ( and bmi a negative one) (Castelli 2007). When mathematics and reading
scores were analyzed against aerobic fitness, the students with a higher level
of fitness outperformed the students with a lower level of fitness (Californian Department of Education 2001).

Neuroanatomy involved in
reading comprehension in children includes the prefrontal cortex (PFC) as well
as the posterior cingulate cortex (PCC) (Maguire
1999). Additionally, one of the
regions in the brain involved in mathematics is the bilateral regions of the
intraparietal sulcus, in children specifically the dorsolateral prefrontal
cortex is also activated.  Both
mathematics and reading require activation of the frontopariteal network.
Interestingly, fitness has also been linked to this network (Colcombe 2004). Therefore, it may follow that children
will potentially perform better academically with an increase in aerobic
fitness.

 

It is important to note that
some studies have found little or no correlation between children’s aerobic fitness
level and academic performance (Ahamed 2007).
However, it is reasonable to assume that physical education is an important part
of children’s wellbeing and that it does not dampen academic achievement,
indeed in some cases it may enhance it.

 

 

Conclusions

 

Exercise presents itself as a novel treatment for a
variety of disorders and diseases. The relationship between aerobic fitness and
neurodegenerative diseases is of crucial importance as the number of people
living to a later age is increasing. This means that, statistically, there is
going to be more people developing these diseases. If prescribed exercise is
incorporated into healthcare policy then there may be a delay in the
development of these diseases. This may result in a reduced economic strain for
healthcare organisations. Additionally, encouraging patients who experience a
first episode with Schizophrenia to engage in regular physical activity has
been shown to quicken their recovery time. The effect of exercise on the
academic achievement of children is also an interesting area as academic
achievement (and inherently cognition) is not something traditionally
associated with physical fitness.

 

Whilst the use of exercise as a treatment for a variety
of diseases provides another treatment option for many patients it is important
to note that studies are not claiming that exercise should be the only form of
treatment issued. Additionally, there may be challenges in getting patients to
comply with exercise programs prescribed to them. This is an interesting and
developing area of research but at present, there has been little investigation
into the molecular mechanisms as to how exercise can have these effects and
further research should be done to determine this. To conclude, exercise, when
used in conjunction with other treatment plans, has the capacity to improve the
symptoms of many patients with neurological diseases.