@ Sydney Bright

Abstract There is a growing body of evidence suggesting that depression is becoming a major health concern for the modern world. Given the multitude of stressors advanced civilization provides, people are increasingly ruminating over the past and future. These repetitive non-constructive thoughts provide stress both in the mind and physically manifest itself in our bodily systems, deteriorating our health on multiple fronts. Not only are cases of depression increasing, but many seem to be resistant to current forms of treatment. These treatments include both pharmaceutical and therapeutic methods. Clinicians need to begin taking a serious look at alternate forms of treatment so they can become more equipped to treat patients with depression. Mindfulness meditation is the practice of focusing one’s thoughts entirely on the body itself and trains the mind to forgo all other extraneous thoughts. This technique not only provides the body an immediate sensation of safety and relaxation, but trains the individual to have better control over repetitive unhealthy thoughts. The more frequent feeling of relaxation coupled with the ability to subdue one’s own rumination decreases the body’s activation of its defense protocols. These defenses, also known as the sympathetic nervous system, when activated too frequently can be extremely detrimental to one’s physical and mental health and is strongly correlated to stress and depression. Much research involving mindfulness meditation has shown that it increases one’s ability to have thought control and decreases sympathetic nervous system activity. This is coupled with a heightened awareness of one’s own body, leading to a general increase in self perception and wellbeing. Dramatically reducing the occurrence of stress and depression. The body of meditation research requires further attention. In particular, studies require more standardized forms of meditation methods and an improvement of experimental design to increase statistical significance. That being said, given the effect mindfulness meditation has on depression, it should be viewed as a potential replacement for the treatment of depression through antidepressants. Antidepressants have a large list of potential side effects, are at times shown to be no more effective than a placebo, and have no evidence of preventing depression once treatment has been terminated. Meditation being costless and side effect free, if truly effective, would be a far more ethical and responsible treatment methods for physicians and therapist to prescribe. Introduction This paper will review existing literature discussing meditation and its potentially remedial effects on depression. It will argue that by providing increased ability to control and recognize non-constructive thoughts, meditation can decrease stress, thereby helping individuals with clinical depression. It is projected that by 2020, depression will become the second most common mental health issue (Kenny & Williams, 2007). Collectively, stress and depression-related symptoms account for a majority of visits to primary care physicians (Greeson et al., 2018). These disorders have become extremely prevalent and are extremely costly for individuals and the entire health care system (Greeson et al., 2018). That being said, it has been shown that 40% of depression patients are resistant to current treatment methods (Kenny & Williams, 2007), demonstrating that the entire system of treating depression is largely wasteful and inefficient, placing an unnecessary burden on society. Therefore, it is crucial that alternative approaches to treatment are explored. When looking at potential treatment methods for depression, it is important to first consider the underlying causes. Depression is a complex mental issue that can manifest itself in a variety of different ways, and can stem from a large number of causes. That being said, there appears to be a distinct connection between stress and depression. Researchers have found that repetitive, non-constructive thoughts can lead to depression, and that individuals with acute stress-induced behaviors and hormonal changes have very similar symptoms to those suffering from depression (Watkins, 2008; Kasala et al., 2014). These symptoms commonly include hypercortisolism, which is a rise in cortisol levels due to an increase in sympathetic nervous system activity. Hypercortisolism can lead to high blood pressure, impaired immune function by decreasing cytokine count, poor antibody response, high blood sugar, increased renal retention of sodium, to name a few (Spreng, 2000; Godbout & Glaser, 2006; Kasala et al., 2014). In short, it is a condition that is extremely detrimental to overall health. Neurologically speaking, the relationship between stress and depression can be attributed partly to atrophy of the hippocampus, which is caused by high levels of stress induced glucocorticoid release (Annells et al., 2016). Modern life is full of stressful situations. People tend to spend large portions of their day ruminating over the past and forecasting for the future. Often, these thoughts bring about worry and regret. Human beings evolved with a “fight or flight” defense response regulated by the sympathetic nervous system in order to protect themselves from physical harm. In modern life, these physical threats are being replaced by mental threats brought upon by our own projections of the past and future (Kuchel & Kuchel, 1991). Not ruminating over such thoughts has been shown to decrease sympathetic nervous system activity (vanOyen Witvliet et al., 2011). There is also a relationship between general cognitive load, and increased sympathetic activity (Mizuno et al., 2011). Therefore, it is of no surprise that high levels of sympathetic nervous system activity is present in cases of major depression (Veith et al., 1994). The author hypothesizes that treatment methods involving improved thought control can remove stressful thoughts, thereby reducing depressive symptoms. These changes in thought patterns will have an effect on increasing parasympathetic nervous system tone and related neurotransmitters, thereby drawing a link between the cognitive skill of removing unconstructive thoughts and the reduction of stress and depression. Alongside this, the general act of meditation causes the body to feel more relaxed and decreases the activation of the sympathetic nervous system, bringing cortisol to lower levels, which increases general health and well-being. These skills will prove not only applicable to patients for depression, but also to any individual suffering from repetitive non-constructive thoughts that hinder their daily function and worsen their bodily health. This paper, through the lens of existing literature, will explore the connection between meditation’s ability to improve thought control and its promise as a treatment for depression. Mindfulness Meditation and the Skills Provided This paper will primarily focus on one of many forms of meditation: mindfulness meditation. Mindfulness meditation is the practice of focusing attention on a single entity, such as one’s breath, in order to take attention away from other, potentially non-constructive thoughts (Wielgosz et al., 2019). Focusing on body and breath in a calm and accepting manner also provides the mind with a sense of safety (Esch, 2014). This technique allows an individual to have an increased awareness of their emotions, and greater control over their thoughts (Barnhofer et al., 2009). Meditation has been shown to increase brain plasticity in the regions used (Lazar et al., 2005). Given the existence of use-dependent brain plasticity, it can be presumed that as meditators use these techniques during their practice, they will also be more easily able to use them in everyday life (Giuliani et al., 2011; Esch, 2014). For example, attention regulation is related to the anterior cingulate cortex (ACC) which is shown to have an increased function in those who practice mindfulness meditation (Rubia, 2009; Hölzel et al., 2011; Lutz, Antoine,Jha, Amishi P.,Dunne, John D.,Saron, 2015). Not only do meditators have increased attention regulation, but they are capable of having greater control of removing irrelevant thoughts. These repetitive thoughts, in the case of depression, usually manifest themselves as negative thoughts regarding their mental condition, poor mood, lack of belief in themselves and an over analysis regarding the consequence and meaning of life events coupled with the expectation of negative outcomes (Watkins, 2008). This is supported by the evidence that alpha bands, which play a role in processing irrelevant information, are faster and significantly more present in those who commonly practice mindfulness meditation (Foxe & Snyder, 2011). Meditation also effects the right amygdala, which is related to the processing of emotions. Reducing depression through the use of SSRIs is partly done by the suppression of right amygdala activity. Those who meditate have reduced right amygdala activity during meditation, and a change in activity was also observed when the subject was no longer meditating (Annells et al., 2016). This indicates that meditation provides more adequate emotional control over incoming stressors, and can potentially act as a replacement for antidepressants. Meditation grants the general awareness and control of emotions, alleviating the body from feeling in danger while granting the individual the ability to recognize unhealthy ruminations and clear them from their thought stream. The Physiologic Responses of Mindfulness Meditation The benefit of thought control is evident when analyzing the result of experiments involving mindfulness meditation. Increases sympathetic nervous system activity is present within depression (Veith et al., 1994). Those who have increased mindfulness show decreased stress and a faster recovery from it (Greeson et al., 2018; Gamaiunova et al., 2019). In these individuals, there is a noticeable reduction in sympathetic activity and responsivity, coupled with an increase in parasympathetic nervous system tone (Hoffman et al., 1982; Esch, 2014). This means the body of a meditator shifts away from activating stressful, fight or flight systems, and relaxed state processes begin to dominate. Stress related neurotransmitters such as norepinephrine and cortisol are also shown to be less present in individuals that practice meditation (Esch et al., 2007; Esch, 2014). This also indicates that meditation has a general effect on physical health. As previously stated, high levels of cortisol have serious effects on bodily health; thus, lessening cortisol will provide general well-being, as well as the cognitive benefits discussed above. Chronic stress has been connected to lower acetylcholine levels. Interestingly enough, the breath of meditators has elevated nitric oxide levels. Presumably because there are higher levels of acetylcholine and morphine, which both increase the activity of oxide-producing enzymes (Esch, 2014). Dopamine is often related inversely to the presence of depression, and it too has been shown to increase amongst those who practice meditation (Dailly et al., 2004; Jung et al., 2010; Esch, 2014). It is also has been suggested that the increase in internalized attention during mediation, triggers activity in brain regions such as the left frontal cortex that are related to positive emotions (Rubia, 2009). This, coupled with the general health benefits of decreasing sympathetic activity and cortisol levels, is likely the reason why meditators often express a general higher satisfaction with their life and are more content (Esch et al., 2007). That being said, meditators also have a higher awareness of their own health. Meditators show an increase use of the ACC and insula, signifying that they have a greater means of modulating the self, alongside pain perception and anticipation. It is theorized that this increase in awareness grants the individual a sense of responsibility to improve their health (Esch, 2014). There is likely a feedback loops that occurs when one meditates: the individual decreases sympathetic nervous system activity, thereby increasing their health and wellbeing, while also gaining a higher perception of their health that results in further attention and improvement. The Missing Component Many metanalytical papers have attempted to synthesize the findings of mediation research. Many conclude, as this paper does, that the main neuronal mechanism of mindfulness generally involves: attention regulation of the body and mind, nonreactivity to experiences, and changes of self-perception (Hölzel et al., 2011; Esch, 2014; Wielgosz et al., 2019). Even though the effects on the autonomic nervous system are discussed, they are seemingly ignored as a key factor contributing to the higher quality of life and state of mind experienced by those that practice meditation. That being said, authors neglect to mention that there are two different arguments being put forth. The first is that people who meditate are, at that moment, putting themselves in a peaceful and quiet mindset that makes the body feel safe, thereby increasing parasympathetic nervous system activity (Esch, 2014). The second is that it is the skills learned from the meditation that allow for individuals to remove the unconstructive thoughts in the face of stressful situations, thereby preventing an increase in sympathetic nervous system activity. Of course, these two mechanisms may both occur, and perhaps due to the change in brain plasticity, the practices of stress relief during meditation aids the patient in using those same skill in everyday life. However, this distinction is key not only for general scientific understanding, but also for future research. The existence of the two possible mechanisms suggests the need for further investigation. Researchers, rather than observing the improvement in self-reported depression scores, should be focusing on changes in autonomic nervous system changes. To differentiate between the two mechanisms, researchers should monitor autonomic nervous system activity during the act of meditation and after a series of prolonged practices. This type of experiment could ascertain whether or not the bulk of decrease in sympathetic nervous system activity and increase in parasympathetic nervous system activity occurs at the moment of meditation, or afterwards through the skills obtained. Perhaps the two systems change at different times, or the changes are evenly distributed across both events. Either way, this type of experiment seems necessary to gain a deeper understanding of the mechanisms involved in treating depression. Furthermore, these distinctions are important in determining which techniques of mindfulness meditation provide the best results. Criticisms A key criticism of meditation research is that the method of meditation used in the studies is not constant. There are many forms of meditation practiced around the world, and many have different purposes. The most traditional and commonly practiced forms of meditation involve focusing attention on a single thing, which makes the research of mindfulness meditation particularly difficult because many will consider a wide range of practices to fall under the classification of mindfulness meditation. Even in this paper, that focuses exclusively on mindfulness meditation research, papers were presented that consider Tai Chi as inclusive to that criteria (Esch et al., 2007). Given the coordination of movements and the need for an instructor, Tai Chi can hardly be classified as a means of training thought control. Nonetheless, that example is quite extreme and most mindfulness-based meditation research involves one of these 4 types: traditional meditation, meditation in a clinical setting, mindfulness in a transient state and mindfulness as a dispositional trait (Chiesa et al., 2014). Despite the similarities, these all have vast differences in terms of how the meditation is practiced. For example, traditional meditation is done alone, and a more silent environment helps an individual focus on their breath. In a clinical setting, researchers conduct mindfulness-based cognitive therapy (MBCT), in which the meditation is done in a group setting led by a teacher (Kenny & Williams, 2007). In this particular study of Kenny and Williams 2007, patients were also assigned homework of 1 hour of practice per day of yoga or meditation. Even though yoga is traditionally a physical form of mindfulness meditation, it is not in western cultures. In western cultures, Yoga becomes more a practice of listening to an instructor and stretching, which is not conducive to focusing solely on the breath. This highlights the difficulty of deciding whether or not the benefits of meditation come from the practice itself or the skills learned from it, since all of these studies use methods of meditation that vaguely resemble one another in practice. If all studies use different forms of meditation, then no matter how similar the results across studies are, there is no clear conclusion on the mechanism by which these changes occur. An obvious solution to this problem is to create a method of meditation that is traditionally used by all meditators, and to have many studies done all using the same method. Since it would be hard to mandate all researchers to use the same procedures, another option is to conduct more research on the meditators’ brain activity at the time of meditation. Perhaps these observations would shed more light on the neurological processes occurring during meditation, and these results would hopefully suggest which techniques provide the same types of skills and mental processes. That being said, it is also important for researchers to consider the mechanism by which the skills of thought control are brought about before the initiation of the experiment. Practices like Thai Chi and Yoga being from eastern cultures does not classify them as mindfulness meditation and effective procedures to promote thought control. The conclusions of some experiments discussed in this paper need to be taken with skepticism. Many studies are conducted with small sample sizes (Kenny & Williams, 2007; Barnhofer et al., 2009; Kasala et al., 2014). There are even studies, such as the Kenny and Williams study in 2007 discussed above that do not have a control group or any other group to make a comparison to. They even allowed the patients to take their regular medications for their disorders. This, alongside the absence of a control group, makes it extremely difficult to scientifically show that the MBCT was the reason for the decrease in depression scores at all. While other studies had a well-constructed design, most studies that conduct a T-test or ANOVA in their analysis fail to show that their data is normally distributed (Kenny & Williams, 2007; Barnhofer et al., 2009; Greeson et al., 2018). A normal distribution of data is a key assumption for both of these commonly used statistical test, and without proper proof of normality, the results of these test are questionable at best. Sadly, much of scientific literature contains these forms of statistical errors (Halsey et al., 2015). Though these flaws are not present in all mindfulness meditation experiments, the use of these studies as concrete evidence of its effectiveness is rightfully scrutinized. Most studies tend to have similar results, which suggests that mindfulness meditation effects depression. Nonetheless, given the design flaws of experiments and inconsistency in meditation methods, these studies should be used more as an indicator of the existence of a relationship between mindfulness meditation and depression than evidence that such a relationship exists. Much more diligent and thorough work is required for there to be scientific validity, and the ability to claim that meditation is truly a useful method of treatment. To start, many of these experiments should be repeated with improvements to their design, such as including control groups and more consistent methods of mediation, in order to validate the significance of their p-values. This will provide much more statistically significant evidence suggesting that mindfulness meditation is the true cause of the alleviation of depressive symptoms. Conclusion Despite the lack of concrete evidence and methods, there is a case to adopt this practice sooner rather than later. Given most experiments involving mindfulness meditation and its effects on depression share similar results, it is reasonable to assume that there is some true effect mindfulness meditation has on alleviating the disorder. The aim of the physician should be to provide a patient that has emotional challenges the tools and skills needed to manage and subdue the unhealthy habits of thinking on their own. Traditionally, this method is through the use of pharmaceutical drugs that act to change brain chemistry. This is not only a costly expense on the individual, but there is growing evidence suggesting that many antidepressants are not much more effective than a placebo (Kirsch et al., 2002; Antonuccio et al., 2002). Not only that, but antidepressant have numerous negative long-term side effects, such as withdrawals, sexual problems, weight gain and becoming emotionally numb (Masand & Gupta, 2002; Cartwright et al., 2016). There is also no publish evidence to claim that antidepressants reduce the risk of depression once the treatment has ended (Annells et al., 2016). Therefore, antidepressants should not be thought of as a viable clinical solution in the long-run. Meditation on the other hand is completely free, and can be a useful practice in an individual’s personal life. Given its simplicity, it is also void of negative side effects, and in that sense is a much more ethical and risk-averse form of treatment from a clinical standpoint. Therefore, it is prudent that the scientific community give increased attention to meditation research, so that we can further understand its benefits and perfect its techniques, to potentially help all those who suffer from depression in a safe and cost-effective manner. Works Cited Annells S, Kho K & Bridge P (2016). Meditate don’t medicate: How medical imaging evidence supports the role of meditation in the treatment of depression. Radiography 22, e54–e58. Antonuccio DO, Burns DD & Danton WG (2002). Antidepressants: A triumph of marketing over science? Prev Treat; DOI: 10.1037/1522-3736.5.1.525c. Barnhofer T, Crane C, Hargus E, Amarasinghe M, Winder R & Williams JMG (2009). Mindfulness-based cognitive therapy as a treatment for chronic depression: A preliminary study. Behav Res Ther 47, 366–373. Cartwright C, Gibson K, Read J, Cowan O & Dehar T (2016). Long-term antidepressant use: patient perspectives of benefits and adverse effects. Patient Prefer Adherence 10, 1401–1407. 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Possible health effects of noise induced cortisol increase. Noise Health 2, 59–64. vanOyen Witvliet C, DeYoung NJ, Hofelich AJ & DeYoung PA (2011). Compassionate reappraisal and emotion suppression as alternatives to offense-focused rumination: Implications for forgiveness and psychophysiological well-being. J Posit Psychol 6, 286–299. Veith RC, Lewis N, Linares OA, Barnes RF, Raskind MA, Villacres EC, Murburg MM, Ashleigh EA, Castillo S, Peskind ER, Pascualy M & Halter JB (1994). Sympathetic Nervous System Activity in Major Depression. Arch Gen Psychiatry 51, 411. Watkins ER (2008). Constructive and unconstructive repetitive thought. Psychol Bull 134, 163–206. Wielgosz J, Goldberg SB, Kral TRA, Dunne JD & Davidson RJ (2019). Mindfulness Meditation and Psychopathology. Annu Rev Clin Psychol 15, 285–316. **Abstract** There is a growing body of evidence suggesting that depression is becoming a major health concern for the modern world. Given the multitude of stressors advanced civilization provides, people are increasingly ruminating over the past and future. These repetitive non-constructive thoughts provide stress both in the mind and physically manifest itself in our bodily systems, deteriorating our health on multiple fronts. Not only are cases of depression increasing, but many seem to be resistant to current forms of treatment. These treatments include both pharmaceutical and therapeutic methods. Clinicians need to begin taking a serious look at alternate forms of treatment so they can become more equipped to treat patients with depression. Mindfulness meditation is the practice of focusing one’s thoughts entirely on the body itself and trains the mind to forgo all other extraneous thoughts. This technique not only provides the body an immediate sensation of safety and relaxation, but trains the individual to have better control over repetitive unhealthy thoughts. The more frequent feeling of relaxation coupled with the ability to subdue one’s own rumination decreases the body’s activation of its defense protocols. These defenses, also known as the sympathetic nervous system, when activated too frequently can be extremely detrimental to one’s physical and mental health and is strongly correlated to stress and depression. Much research involving mindfulness meditation has shown that it increases one’s ability to have thought control and decreases sympathetic nervous system activity. This is coupled with a heightened awareness of one’s own body, leading to a general increase in self perception and wellbeing. Dramatically reducing the occurrence of stress and depression.  The body of meditation research requires further attention. In particular, studies require more standardized forms of meditation methods and an improvement of experimental design to increase statistical significance. That being said, given the effect mindfulness meditation has on depression, it should be viewed as a potential replacement for the treatment of depression through antidepressants. Antidepressants have a large list of potential side effects, are at times shown to be no more effective than a placebo, and have no evidence of preventing depression once treatment has been terminated. Meditation being costless and side effect free, if truly effective, would be a far more ethical and responsible treatment methods for physicians and therapist to prescribe. **Introduction** This paper will review existing literature discussing meditation and its potentially remedial effects on depression. It will argue that by providing increased ability to control and recognize non-constructive thoughts, meditation can decrease stress, thereby helping individuals with clinical depression. It is projected that by 2020, depression will become the second most common mental health issue (Kenny & Williams, 2007). Collectively, stress and depression-related symptoms account for a majority of visits to primary care physicians (Greeson *et al.*, 2018). These disorders have become extremely prevalent and are extremely costly for individuals and the entire health care system (Greeson *et al.*, 2018). That being said, it has been shown that 40% of depression patients are resistant to current treatment methods (Kenny & Williams, 2007), demonstrating that the entire system of treating depression is largely wasteful and inefficient, placing an unnecessary burden on society. Therefore, it is crucial that alternative approaches to treatment are explored. When looking at potential treatment methods for depression, it is important to first consider the underlying causes.  Depression is a complex mental issue that can manifest itself in a variety of different ways, and can stem from a large number of causes. That being said, there appears to be a distinct connection between stress and depression. Researchers have found that repetitive, non-constructive thoughts can lead to depression, and that individuals with acute stress-induced behaviors and hormonal changes have very similar symptoms to those suffering from depression (Watkins, 2008; Kasala *et al.*, 2014). These symptoms commonly include hypercortisolism, which is a rise in cortisol levels due to an increase in sympathetic nervous system activity. Hypercortisolism can lead to high blood pressure, impaired immune function by decreasing cytokine count, poor antibody response, high blood sugar, increased renal retention of sodium, to name a few (Spreng, 2000; Godbout & Glaser, 2006; Kasala *et al.*, 2014). In short, it is a condition that is extremely detrimental to overall health. Neurologically speaking, the relationship between stress and depression can be attributed partly to atrophy of the hippocampus, which is caused by high levels of stress induced glucocorticoid release (Annells *et al.*, 2016). Modern life is full of stressful situations. People tend to spend large portions of their day ruminating over the past and forecasting for the future. Often, these thoughts bring about worry and regret. Human beings evolved with a “fight or flight” defense response regulated by the sympathetic nervous system in order to protect themselves from physical harm. In modern life, these physical threats are being replaced by mental threats brought upon by our own projections of the past and future (Kuchel & Kuchel, 1991). Not ruminating over such thoughts has been shown to decrease sympathetic nervous system activity (vanOyen Witvliet *et al.*, 2011). There is also a relationship between general cognitive load, and increased sympathetic activity (Mizuno *et al.*, 2011). Therefore, it is of no surprise that high levels of sympathetic nervous system activity is present in cases of major depression (Veith *et al.*, 1994). The author hypothesizes that treatment methods involving improved thought control can remove stressful thoughts, thereby reducing depressive symptoms. These changes in thought patterns will have an effect on increasing parasympathetic nervous system tone and related neurotransmitters, thereby drawing a link between the cognitive skill of removing unconstructive thoughts and the reduction of stress and depression. Alongside this, the general act of meditation causes the body to feel more relaxed and decreases the activation of the sympathetic nervous system, bringing cortisol to lower levels, which increases general health and well-being. These skills will prove not only applicable to patients for depression, but also to any individual suffering from repetitive non-constructive thoughts that hinder their daily function and worsen their bodily health. This paper, through the lens of existing literature, will explore the connection between meditation’s ability to improve thought control and its promise as a treatment for depression. **Mindfulness Meditation and the Skills Provided** This paper will primarily focus on one of many forms of meditation: mindfulness meditation. Mindfulness meditation is the practice of focusing attention on a single entity, such as one’s breath, in order to take attention away from other, potentially non-constructive thoughts (Wielgosz *et al.*, 2019). Focusing on body and breath in a calm and accepting manner also provides the mind with a sense of safety (Esch, 2014). This technique allows an individual to have an increased awareness of their emotions, and greater control over their thoughts (Barnhofer *et al.*, 2009). Meditation has been shown to increase brain plasticity in the regions used (Lazar *et al.*, 2005). Given the existence of use-dependent brain plasticity, it can be presumed that as meditators use these techniques during their practice, they will also be more easily able to use them in everyday life (Giuliani *et al.*, 2011; Esch, 2014). For example, attention regulation is related to the anterior cingulate cortex (ACC) which is shown to have an increased function in those who practice mindfulness meditation (Rubia, 2009; Hölzel *et al.*, 2011; Lutz, Antoine,Jha, Amishi P.,Dunne, John D.,Saron, 2015). Not only do meditators have increased attention regulation, but they are capable of having greater control of removing irrelevant thoughts. These repetitive thoughts, in the case of depression, usually manifest themselves as negative thoughts regarding their mental condition, poor mood, lack of belief in themselves and an over analysis regarding the consequence and meaning of life events coupled with the expectation of negative outcomes (Watkins, 2008). This is supported by the evidence that alpha bands, which play a role in processing irrelevant information, are faster and significantly more present in those who commonly practice mindfulness meditation (Foxe & Snyder, 2011). Meditation also effects the right amygdala, which is related to the processing of emotions. Reducing depression through the use of SSRIs is partly done by the suppression of right amygdala activity. Those who meditate have reduced right amygdala activity during meditation, and a change in activity was also observed when the subject was no longer meditating (Annells *et al.*, 2016). This indicates that meditation provides more adequate emotional control over incoming stressors, and can potentially act as a replacement for antidepressants. Meditation grants the general awareness and control of emotions, alleviating the body from feeling in danger while granting the individual the ability to recognize unhealthy ruminations and clear them from their thought stream. **The Physiologic Responses of Mindfulness Meditation**             The benefit of thought control is evident when analyzing the result of experiments involving mindfulness meditation. Increases sympathetic nervous system activity is present within depression (Veith *et al.*, 1994). Those who have increased mindfulness show decreased stress and a faster recovery from it (Greeson *et al.*, 2018; Gamaiunova *et al.*, 2019). In these individuals, there is a noticeable reduction in sympathetic activity and responsivity, coupled with an increase in parasympathetic nervous system tone (Hoffman *et al.*, 1982; Esch, 2014). This means the body of a meditator shifts away from activating stressful, fight or flight systems, and relaxed state processes begin to dominate. Stress related neurotransmitters such as norepinephrine and cortisol are also shown to be less present in individuals that practice meditation (Esch *et al.*, 2007; Esch, 2014). This also indicates that meditation has a general effect on physical health. As previously stated, high levels of cortisol have serious effects on bodily health; thus, lessening cortisol will provide general well-being, as well as the cognitive benefits discussed above. Chronic stress has been connected to lower acetylcholine levels. Interestingly enough, the breath of meditators has elevated nitric oxide levels. Presumably because there are higher levels of acetylcholine and morphine, which both increase the activity of oxide-producing enzymes (Esch, 2014). Dopamine is often related inversely to the presence of depression, and it too has been shown to increase amongst those who practice meditation (Dailly *et al.*, 2004; Jung *et al.*, 2010; Esch, 2014). It is also has been suggested that the increase in internalized attention during mediation, triggers activity in brain regions such as the left frontal cortex that are related to positive emotions (Rubia, 2009). This, coupled with the general health benefits of decreasing sympathetic activity and cortisol levels, is likely the reason why meditators often express a general higher satisfaction with their life and are more content (Esch *et al.*, 2007). That being said, meditators also have a higher awareness of their own health. Meditators show an increase use of the ACC and insula, signifying that they have a greater means of modulating the self, alongside pain perception and anticipation. It is theorized that this increase in awareness grants the individual a sense of responsibility to improve their health (Esch, 2014). There is likely a feedback loops that occurs when one meditates: the individual decreases sympathetic nervous system activity, thereby increasing their health and wellbeing, while also gaining a higher perception of their health that results in further attention and improvement. **The Missing Component** Many metanalytical papers have attempted to synthesize the findings of mediation research. Many conclude, as this paper does, that the main neuronal mechanism of mindfulness generally involves: attention regulation of the body and mind, nonreactivity to experiences, and changes of self-perception (Hölzel *et al.*, 2011; Esch, 2014; Wielgosz *et al.*, 2019). Even though the effects on the autonomic nervous system are discussed, they are seemingly ignored as a key factor contributing to the higher quality of life and state of mind experienced by those that practice meditation. That being said, authors neglect to mention that there are two different arguments being put forth. The first is that people who meditate are, at that moment, putting themselves in a peaceful and quiet mindset that makes the body feel safe, thereby increasing parasympathetic nervous system activity (Esch, 2014). The second is that it is the skills learned from the meditation that allow for individuals to remove the unconstructive thoughts in the face of stressful situations, thereby preventing an increase in sympathetic nervous system activity. Of course, these two mechanisms may both occur, and perhaps due to the change in brain plasticity, the practices of stress relief during meditation aids the patient in using those same skill in everyday life. However, this distinction is key not only for general scientific understanding, but also for future research. The existence of the two possible mechanisms suggests the need for further investigation. Researchers, rather than observing the improvement in self-reported depression scores, should be focusing on changes in autonomic nervous system changes. To differentiate between the two mechanisms, researchers should monitor autonomic nervous system activity during the act of meditation and after a series of prolonged practices. This type of experiment could ascertain whether or not the bulk of decrease in sympathetic nervous system activity and increase in parasympathetic nervous system activity occurs at the moment of meditation, or afterwards through the skills obtained. Perhaps the two systems change at different times, or the changes are evenly distributed across both events. Either way, this type of experiment seems necessary to gain a deeper understanding of the mechanisms involved in treating depression. Furthermore, these distinctions are important in determining which techniques of mindfulness meditation provide the best results. **Criticisms**             A key criticism of meditation research is that the method of meditation used in the studies is not constant. There are many forms of meditation practiced around the world, and many have different purposes. The most traditional and commonly practiced forms of meditation involve focusing attention on a single thing, which makes the research of mindfulness meditation particularly difficult because many will consider a wide range of practices to fall under the classification of mindfulness meditation. Even in this paper, that focuses exclusively on mindfulness meditation research, papers were presented that consider Tai Chi as inclusive to that criteria (Esch *et al.*, 2007). Given the coordination of movements and the need for an instructor, Tai Chi can hardly be classified as a means of training thought control. Nonetheless, that example is quite extreme and most mindfulness-based meditation research involves one of these 4 types: traditional meditation, meditation in a clinical setting, mindfulness in a transient state and mindfulness as a dispositional trait (Chiesa *et al.*, 2014). Despite the similarities, these all have vast differences in terms of how the meditation is practiced. For example, traditional meditation is done alone, and a more silent environment helps an individual focus on their breath. In a clinical setting, researchers conduct mindfulness-based cognitive therapy (MBCT), in which the meditation is done in a group setting led by a teacher (Kenny & Williams, 2007). In this particular study of Kenny and Williams 2007, patients were also assigned homework of 1 hour of practice per day of yoga or meditation. Even though yoga is traditionally a physical form of mindfulness meditation, it is not in western cultures. In western cultures, Yoga becomes more a practice of listening to an instructor and stretching, which is not conducive to focusing solely on the breath. This highlights the difficulty of deciding whether or not the benefits of meditation come from the practice itself or the skills learned from it, since all of these studies use methods of meditation that vaguely resemble one another in practice. If all studies use different forms of meditation, then no matter how similar the results across studies are, there is no clear conclusion on the mechanism by which these changes occur. An obvious solution to this problem is to create a method of meditation that is traditionally used by all meditators, and to have many studies done all using the same method. Since it would be hard to mandate all researchers to use the same procedures, another option is to conduct more research on the meditators’ brain activity at the time of meditation. Perhaps these observations would shed more light on the neurological processes occurring during meditation, and these results would hopefully suggest which techniques provide the same types of skills and mental processes. That being said, it is also important for researchers to consider the mechanism by which the skills of thought control are brought about before the initiation of the experiment. Practices like Thai Chi and Yoga being from eastern cultures does not classify them as mindfulness meditation and effective procedures to promote thought control.              The conclusions of some experiments discussed in this paper need to be taken with skepticism. Many studies are conducted with small sample sizes (Kenny & Williams, 2007; Barnhofer *et al.*, 2009; Kasala *et al.*, 2014). There are even studies, such as the Kenny and Williams study in 2007 discussed above that do not have a control group or any other group to make a comparison to. They even allowed the patients to take their regular medications for their disorders. This, alongside the absence of a control group, makes it extremely difficult to scientifically show that the MBCT was the reason for the decrease in depression scores at all. While other studies had a well-constructed design, most studies that conduct a T-test or ANOVA in their analysis fail to show that their data is normally distributed (Kenny & Williams, 2007; Barnhofer *et al.*, 2009; Greeson *et al.*, 2018). A normal distribution of data is a key assumption for both of these commonly used statistical test, and without proper proof of normality, the results of these test are questionable at best. Sadly, much of scientific literature contains these forms of statistical errors (Halsey *et al.*, 2015). Though these flaws are not present in all mindfulness meditation experiments, the use of these studies as concrete evidence of its effectiveness is rightfully scrutinized. Most studies tend to have similar results, which suggests that mindfulness meditation effects depression. Nonetheless, given the design flaws of experiments and inconsistency in meditation methods, these studies should be used more as an indicator of the existence of a relationship between mindfulness meditation and depression than evidence that such a relationship exists. Much more diligent and thorough work is required for there to be scientific validity, and the ability to claim that meditation is truly a useful method of treatment. To start, many of these experiments should be repeated with improvements to their design, such as including control groups and more consistent methods of mediation, in order to validate the significance of their p-values. This will provide much more statistically significant evidence suggesting that mindfulness meditation is the true cause of the alleviation of depressive symptoms. **Conclusion**             Despite the lack of concrete evidence and methods, there is a case to adopt this practice sooner rather than later. Given most experiments involving mindfulness meditation and its effects on depression share similar results, it is reasonable to assume that there is some true effect mindfulness meditation has on alleviating the disorder. The aim of the physician should be to provide a patient that has emotional challenges the tools and skills needed to manage and subdue the unhealthy habits of thinking on their own. Traditionally, this method is through the use of pharmaceutical drugs that act to change brain chemistry. This is not only a costly expense on the individual, but there is growing evidence suggesting that many antidepressants are not much more effective than a placebo (Kirsch *et al.*, 2002; Antonuccio *et al.*, 2002). Not only that, but antidepressant have numerous negative long-term side effects, such as withdrawals, sexual problems, weight gain and becoming emotionally numb (Masand & Gupta, 2002; Cartwright *et al.*, 2016). There is also no publish evidence to claim that antidepressants reduce the risk of depression once the treatment has ended (Annells *et al.*, 2016). Therefore, antidepressants should not be thought of as a viable clinical solution in the long-run. Meditation on the other hand is completely free, and can be a useful practice in an individual’s personal life. Given its simplicity, it is also void of negative side effects, and in that sense is a much more ethical and risk-averse form of treatment from a clinical standpoint. 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