THE EFFECT THAT EXERCISE HAS ON COGNITIVE FUNCTIONS – A REVIEW 1 The Effect that Exercise has on Cognitive Functions – A Review Bachelor Degree Project in Cognitive Neuroscience 15 ECTS Spring term 2019 Caroline Andersérs Supervisor: Anders Milton Examiner: Sakari Kallio THE EFFECT THAT EXERCISE HAS ON COGNITIVE FUNCTIONS – A REVIEW 2 Abstract My aim for this literature review is to present and discuss a possible relationship between physical exercise and different kinds of cognitive functions. With the increasing interest on the topic, more studies have been conducted and the results from the studies have been a little ambiguous. The most part of the studies has been showing that exercise has a positive effect on cognitive functions. The evidence from the studies also says that exercise can help the brain to regulate the production of new neurons and to increase brain volume in the prefrontal and temporal areas. That can be very beneficial for elderly people with dementia, Alzheimer's disease or other cognitive declines. Evidence of exercise combined with the right nutrition can enhance cognitive performance even more but to establish this more research is needed. Keywords: cognitive functions, physical exercise, cognitive test, neurogenesis, nutrition THE EFFECT THAT EXERCISE HAS ON COGNITIVE FUNCTIONS – A REVIEW 3 Table of Contents 1. Introduction ..................................................................................................................................... 4 2. Cognitive Functions ........................................................................................................................ 6 3. Methods to Measure Cognitive Functions ....................................................................................... 9 4. Exercise and Cognitive Function ................................................................................................... 13 5. Possible Mechanisms .................................................................................................................... 20 5.1. Neurogenesis, Hippocampal Plasticity, and Exercise ................................................................ 21 5.2. Brain Volume, Gray and White Matter ...................................................................................... 23 6. Nutrition, Exercise and Cognitive Functions ................................................................................ 25 7. Discussion ..................................................................................................................................... 28 8. Conclusion ..................................................................................................................................... 31 9. References ..................................................................................................................................... 32 THE EFFECT THAT EXERCISE HAS ON COGNITIVE FUNCTIONS – A REVIEW 4 1. Introduction There is a great deal of research indicating that physical exercise helps to improve different cognitive functions in both humans and rodents. Scientists already know that exercise is good for general health and that exercise could prevent different cardiovascular diseases such as high blood pressure and heart attacks (van Praag, 2009). Despite those researchers in the west end of the last century who started to pay attention to what effect physical exercise has, it was already in 1975 that the researchers were starting to pay more attention to this kind of research. In the past fifteen years, the interest of this kind of research has increased and scientists have got a better understanding about the subject but it is still a long way to go before we know all too it (van Praag, 2009). In this kind of research, scientists can use physical activity or physical exercise when they study the effect that physical movement has on cognitive functions. Physical activity and physical exercise are two different things. Physical activity is defined as any bodily movement produced by skeletal muscles that require energy consumption. (Hötting & Röder, 2013). While physical exercise is defined as a bodily movement to enhance or maintain physical fitness, a subcategory of physical activity that is planned, structured, repetitive, and purposeful in the sense that the improvement or maintenance of one or more components of physical fitness is the objective (Hötting & Röder, 2013). There are different kinds of exercise; aerobic and anaerobic. Aerobic exercise is swimming, walking, cycling, etc. to increase your cardiovascular strength and to maximize the capacity of oxygen uptake. While anaerobic exercise is interval training, lifting a weight, etc. to increase short term muscle strength (Hillman, Erickson & Kramer, 2008). This essay is a literature review and to find articles I used the following databases for my search; PsycINFO, PsycArtickles, MEDLINE, ScienceDirect, Academic Search Elite THE EFFECT THAT EXERCISE HAS ON COGNITIVE FUNCTIONS – A REVIEW 5 and Google Scholar. The first article of interest was from 1989 so I choose to look at articles between the years of 1989-2016. I found a large number of articles 8 608 to be exact when I used the terms of physical exercise and cognitive functions. I had to narrow them down so I concentrated on the articles that had the words cognitive function and physical exercise in the title, then I just had 246 articles to sort through. Most of the articles were conducted on elderly people and not so many articles were of adolescents or of young adults the research articles I have chosen mostly use the aerobic exercise. When I first started with this article in 2012 there were 4170 articles with the same search words. That indicates that in the past 5 years the research and publications about physical exercise and cognitive function have doubled and are a more popular subject to study. I think that this is because people are in general getting older and live longer and that results in more people that have a cognitive decline that we can study. Most of the studies were conducted on people with some sort of cognitive impairment such as Alzheimer’s, dementia or mild cognitive impairment (MCI). To narrow it down I have for the most part chosen studies with healthy adults without a cognitive decline. My aim for this essay is to present and discuss a possible relationship between physical exercise and different kinds of cognitive functions. The main focus of the essay will be to present some cognitive functions, to look at the correlation between cognitive functions and physical exercise and what is happening in the brain during exercise. In the essay, I have five sections that I am interested in. The sections are cognitive functions, different types of measurements used to measure cognitive functions, studies that discuss physical exercise and cognitive function and what effect they have on each other, different mechanism and what happens in the brain when we exercise in the end I will have a small section to look at the benefits of nutrition, physical exercise, and cognitive functions. The essay will end with a discussion and a conclusion. THE EFFECT THAT EXERCISE HAS ON COGNITIVE FUNCTIONS – A REVIEW 6 2. Cognitive Functions The term cognition and cognitive function are how we operate in the real world and what makes life richer (Weisberg & Reeves, 2013). It describes how the brain processes information and our ability to perceive the world with a number of different cognitive processes that can be both conscious and unconscious. The different cognitive processes are thinking, language, memory, learning, attention, perception, and reason. Through these processes and by learning new skills we continuing to develop our cognitive functions and the performance of our cognition during most part of our life, but when people get older our cognitive functions start to decrease. The research focus of cognitive functions is mostly on ways how to improve ability, memory, and learning by a number of different factors such as sleep, exercise, chemicals, medicine or diet. A lot of research has also been done on cognitive declines that are known to have a negative effect on cognitive functions such as Alzheimer's, Parkinson's, diabetes, dementia and depression for trying to understand how we can prevent this from happening (Coviello, 2018). Even if there is a number of different cognitive process that is included in cognitive functions I have chosen to narrow it down in my literature review. So I am focusing on the different cognitive processes that are the most common in experimental studies and in cognitive function tests. I will look at two different processes of memory, short-term (working memory) and long-term memory (only referred as memory later in the text), I will look at the process of attention and information processing speed and the process of executive functions. Executive functions defined by Smith et al., (2010) and Mizuno et al., (2011) as a set of cognitive control processes that monitor goal-directed behavior. The cognitive processes associated with executive functions are located in the pre-frontal cortex and is necessary for the control of behavior and include different areas such as attention, working THE EFFECT THAT EXERCISE HAS ON COGNITIVE FUNCTIONS – A REVIEW 7 memory, error detection, problem-solving, reasoning, and planning. The area of the prefrontal cortex is an area that declines with age and so does the cognitive processes. The human memory serves as a