Three short divulgation essays – 3 Increasing well-being: the neuroscience of good habits

©

Leandro Castelluccio

 

Well-being is a broad concept that includes many dimensions, but all are integrated by subjective states of positive mood and long-term pleasure. There are several choices that impact both positively and negatively on our well-being. The impact of small simple acts on our well-being is often underestimated and the usefulness of other things is overestimated, such as food supplements, certain therapies, self-help readings, etc., which do not always have the same empirical support. However, there is an important body of evidence about the positive impact of certain habits and how high the impact can be, which is often unknown In this essay we will review the scientific basis of the effect of exercise, meditation, sleep and nutrition on our well-being from the point of view of neuroscience.


Exercise and well-being

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Exercise has the ability to improve or prevent mental disorders. Following Taylor, Sallis and Needle (1985), mental disorders are of great importance for public health. It has been argued that vigorous physical activity has positive effects on mental health in both clinical and non-clinical populations. The strongest evidence suggests that physical activity and exercise probably alleviate some symptoms associated with mild to moderate depression. The evidence also suggests that physical activity and exercise could provide a beneficial complement to alcoholism and substance abuse programs, improve self-esteem, social skills and cognitive functioning, as well as reduce anxiety symptoms and alter aspects of the coronary disease (type A) related to behavior and physiological response to stressors.

According to Salmon (2001), the emotional effects of exercise remain confusing, as positive and negative outcomes are reported. The results of cross-sectional and longitudinal studies are more consistent in indicating that aerobic exercise training has antidepressant and anxiolytic effects and protects against the harmful consequences of stress. The antidepressant and anxiolytic effects have been demonstrated most clearly in subclinical disorder, and clinical applications have not yet been fully exploited. Cross-sectional studies link exercise habits with protection against the damaging effects of stress on physical and mental health, but the causality is unclear. However, the pattern of evidence suggests that physical exercise recruits a process that confers lasting resistance to stress. Clinically, exercise training continues to offer clinical psychologists a vehicle for non-specific therapeutic, social and psychological processes. It also offers a specific psychological treatment that can be particularly effective for patients for whom more conventional psychological interventions are less acceptable.

According to Guszkowska (2004), meta-analyzes of correlational and experimental studies reveal positive effects of exercise in healthy people and in clinical populations (also in patients with emotional disorders) regardless of sex and age. The benefits are significant, especially in subjects with a high level of anxiety and depression, because there is more room for a possible change. Most of the improvements are caused by rhythmic, aerobic exercises, based on the use of large muscle groups (jogging, swimming, cycling, walking), of moderate and low intensity. They should be done for 15 to 30 minutes and performed at least three times a week in programs of 10 weeks or more.

A more recent article, following Dunn, Trivedi, Kampert, Clark and Chambliss (2005), shows that aerobic exercise at a dose compatible with public health recommendations is an effective treatment for mild to moderate major depressive disorder. However, a lower dose is comparable to the placebo effect. Public health recommendations include 150 minutes of moderate intensity aerobic activity or 75 minutes of vigorous intensity or their equivalent combination per week (Oja & Titze, 2011).

According to Deslandes et al. (2009), specifically, during the aging process, physical exercise could represent a potential adjuvant treatment for neuropsychiatric disorders and cognitive deterioration, helping to delay the onset of neurodegenerative processes. In addition, although exercise itself could act as a stressor, it has been shown to reduce the damaging effects of other stressors when performed at moderate intensities.

According to Cotman and Engesser-Cesar (2002), it is known that exercise in general affects almost all the body’s systems, generating benefits such as an improvement in cardiovascular health, a higher bone mineral density (BMD) and a lower risk of cancer, stroke and diabetes. In addition, exercise is a means to improve and protect brain function. However, many people still do not perform any type of regular exercise. As these authors point out, the dysfunction and degeneration of age-related neurons causes cognitive decline and personality changes in some cases, but many people turn to supplements, such as gingko biloba, as a solution for cognitive disorders, however, there is no evidence that any supplement can maintain brain function at an optimal level during the aging process. But, we now know about the existence of growth factors, such as brain-derived neurotrophic factor (BDNF), which has neurons as targets, a molecule that has the ability to protect neurons, increase neuronal plasticity, improve learning and help in the general development and maintenance of the brain.

BDNF is able to mediate the beneficial effects of exercise on brain plasticity. This factor supports the health and functioning of the primary neuronal type in the brain, the glutamatergic neurons, which are the main projection neurons that connect the cognitive, sensory and brain-motor regions. BDNF is synthesized in the cell body and transported back and forth to the synapses, where neuronal communication occurs. In addition to mediating synaptic efficacy, BDNF also promotes differentiation, neurite extension, and survival of a variety of neuronal populations in culture and in vivo. BDNF is regulated by neuronal activity and the mechanisms that induce BDNF, such as exercise, also improve learning (Cotman & Engesser-Cesar, 2002). For example, in clinical studies, exercise increases brain volume in areas involved in executive processing, improves cognition in children with cerebral palsy and improves phonemic ability in school children with reading difficulties (Plowman, 2008). The latter author points out that moderate physical activity is important for young people whose brains are very plastic and perhaps even more critical for young people with physical disabilities. In addition, according to the study by Drollette et al. (2014), whose results replicate previous research that reports the beneficial influence of acute aerobic exercise on cognitive performance in children, children with less capacity for inhibitory control can benefit the most from individual exercises. The data demonstrates the differential effect of physical activity in individuals who vary in inhibitory control and further support the role of aerobic exercise for brain health during development.

Recently, microarray analysis of high-density oligonucleotides has shown that, in addition to increasing BDNF levels, exercise mobilizes the gene expression profiles that would be predicted to benefit brain plasticity processes (Cotman & Berchtold, 2002).

On the other hand, according to Ma (2008), the positive regulation of BDNF and neurogenesis imply the down-active pathway of the neurobiological mechanisms of the effects of exercise. It is suggested that activation of norepinephrine (NE) through β-adrenergic receptors may be essential for up-regulation of BDNF-induced exercise. The up-active route, on the other hand, is associated with improvements of various neurotransmitters systems afferent to hippocampus, including NE, serotonin (5-hydroxytryptamine, 5-HT), acetylcholine (ACh) and acid γ-aminobutyric acid (GABA). In addition, according to Sutoo and Akiyama, (1996) exercise leads to an increase in the level of calcium in the brain. This, in turn, improves the synthesis of dopamine, through this increase, dopamine modifies affects brain function, which could induce physiological, behavioral and psychological changes.

Following Cotman, Berchtold and Christie (2007), studies in humans and other animals show that exercise impacts many aspects of brain function and has broad effects on the overall health of the brain. The benefits of exercise have been better defined for learning and memory, protection against neurodegeneration and relief from depression, especially in elderly populations. Exercise increases synaptic plasticity by directly affecting the synaptic structure and enhancing synaptic strength, and by strengthening the underlying systems that support plasticity, including neurogenesis, metabolism, and vascular function. This structural and functional change induced by exercise has been documented in several regions of the brain, but has been studied better in the hippocampus. As we mentioned earlier, growth factors are the key elements of these effects. In addition, a common mechanism underlying the central and peripheral effects of exercise may be related to inflammation, which can affect the growth factor of signaling both systemically and in the brain. Therefore, through the regulation of growth factors and the reduction of central and peripheral risk factors, exercise ensures a successful brain function (Cotman, Berchtold, & Christie, 2007).

On the other hand, studies that examine the intensity of exercise required to optimize neurotrophins suggest that moderation is important. Sustained increases in neurotrophin levels occur with prolonged low intensity exercise, while higher intensity exercise, in a brain injury rat model, elevates the stress hormone, corticosterone (Plowman, 2008).

Meditation and well-being

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Research has provided evidence of improvements induced by meditation in psychological and physiological well-being, including benefits in higher order cognitive functions by modifying brain activity (Luders, Toga, Lepore, & Gaser, 2009). According to the research of these authors, correlates of long-term meditation were detected, with significantly larger volumes of gray matter in the meditators of the right orbital-frontal cortex, as well as in the right thalamus and the left inferior temporal gyrus when co-varying for age and/or lowering applied statistical thresholds. The meditators also showed significantly larger volumes of the right hippocampus. These orbito-frontal and hippocampal regions have been implicated in emotional regulation and response control (following Luders et al., 2009). According to the authors, the larger volumes in these regions could explain the unique skills and habits of meditators to cultivate positive emotions, maintain emotional stability and participate in conscious behaviors. This is just one of hundreds of papers that show lasting effects on brain volume and function.

One type of meditation in particular called “mindfulness” produces several positive psychological effects, including greater subjective well-being, a reduction in the psychological symptoms of emotional reactivity, and a better regulation of behavior (Keng, Smoski, & Robins, 2011). With all these benefits, mindfulness meditation has been increasingly incorporated into psychotherapeutic interventions. Evidence suggests that the practice of mindfulness is associated with neuroplastic changes in the anterior cingulate cortex, the insula, the temporoparietal junction, the fronto-limbic network and the default networks (Hölzel et al., 2011).

Conscious meditation also has a major impact on the regulation of pain. Following Zeidan, Grant, Brown, McHaffie and Coghill (2012), the cognitive modulation of pain is influenced by a series of factors that range from attention, beliefs, conditioning, expectations, mood and the regulation of the emotional responses to stressful sensory events. Recently, it has been discovered that mindfulness meditation attenuates pain through some of these mechanisms, including improved cognitive and emotional control, as well as altering the contextual evaluation of sensory events. According to the brain data, when comparing the neuronal responses during the anticipation of pain between a group with meditation experience and a control group without meditation experience, a region in the medial prefrontal cortex/anterior rostral cingulate cortex (mPFC/rACC) was activated much more in the meditation group, with greater activation predicting the reduction of unpleasant pain ratings. In the control group, an opposite correlation was found with less general activity. There is also evidence of greater activation of meditators in pain-related regions, such as the dorsal anterior cingulate cortex (dACC), the insula (INS) and the thalamus (Thal), but it is drastically reduced in the areas involved in pain evaluation, emotion and memory: medial prefrontal cortex, orbitofrontal cortex (OFC), amygdala and dorsolateral prefrontal cortex (DLPFC) (Zeidan, Grant, Brown, McHaffie, & Coghill, 2012).

This makes sense when we think about the goal of mindfulness meditation, which involves orienting oneself to ongoing events and experiences in a receptive and attentive way, without judging, which denotes an experiential processing mode, which has implications for the way we perceive and respond to situations of stress. Mindfulness would then promote more objectively informed ways of acting in stressful situations, which can then be seen in more benign or neutral terms. This is a way that mindfulness can also help with emotional problems. The evidence supports this, demonstrating that mindfulness promotes desensitization and reduction of emotional reactivity to potentially threatening stimuli (Weinstein, Brown, & Ryan, 2009). Therefore, the technique of mindfulness is a method in which thoughts are experienced as transitory, more related to psychological events than to reflections of absolute reality. This practice can facilitate and strengthen this capacity for a positive re-evaluation.

According to Modinos, Ormel and Aleman (2010), it has been shown that the regulation of negative emotion through re-evaluation induces greater prefrontal activity and less activity of the amygdala. Individual differences in dispositional attention reflect differences in the recognition, detachment and regulation typical of current experience, and it is thought that they also function as a top-down control mechanism. In the study of these authors, re-evaluation induced activity in a brain network involving predominantly dorsal portions of the prefrontal cortex, replicating previous studies. A voxelwise regression analysis showed that individual differences in the tendency to be conscious predicted activity in the neural regions underlying the revaluation, with activation of the dorsomedial prefrontal cortex increasing with more features of mindfulness. In addition, this prefrontal activation was inversely correlated with the response of the amygdala to negative scenes, further supporting its role in the negative regulation of emotion-generating regions.

In addition, mindfulness meditation could induce an experiential mode of information processing. There are several studies that approach this subject of the experiential versus conceptual way. According to Gadeikis, Bos, Schweizer, Murphy and Dunn (2017), there are indications that participating in experiential processing (through direct awareness of sensory and body experience) reinforces the experience of positive emotion. In their experiment, a greater spontaneous use of experiential processing during a memory task was associated with a greater experience of happiness. In addition, experiential processing increased the experience of happiness in relation to other conditions, although not all. The results suggest that getting involved in experiential processing is an effective way to regulate the positive experience of emotion during positive memory recall.

Conscious meditation also has the potential to increase immune function. Such as Davidson et al. (2003) found, significant increases were observed in the concentration of antibodies for the influenza vaccine among the subjects of the meditation group compared to those of the waiting list control group. The magnitude of the increase in brain activation on the left side predicted the magnitude of the increase in antibodies to the vaccine.

In addition, attention-based interventions that focus on increasing awareness of a person’s thoughts, emotions and actions have been shown to improve specific aspects of poor executive functioning (EF), including attention, cognitive control and the regulation of emotions. Poor executive function (EF) has been associated with a series of short and long-term problems throughout life, including high rates of attention deficit hyperactivity disorder, depression, drug abuse and antisocial behavior (Tang, Yang, Leve, & Harold, 2012). According to these authors, a specific intervention based on mindfulness, the integral body and mind training of (IBMT), shows improvements in specific components of EF. The specific neuronal circuits of the anterior cingulate and the autonomic nervous system are two brain mechanisms that could be the basis of the improvements related to the IBMT.

Furthermore, mindfulness-based stress reduction (MBSR) is a clinically standardized meditation that has shown constant efficacy for many mental and physical disorders. However, less attention has been paid to the possible benefits it can have in healthy subjects (Chiesa & Serretti, 2009). The meta-analysis of these authors reveals that the MBSR and standard relaxation training were equally able to reduce stress, but the MBSR was able to reduce ruminant thinking and trait anxiety, as well as increase empathy and self compassion. In general, MBSR can reduce stress levels in healthy people.

Sleep and well-being

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The conservation of sleep in all animal species suggests that sleep fulfills a vital function. Sleep has a critical function to ensure metabolic homeostasis. The sleep-restoring function may be a consequence of the improved elimination of potentially neurotoxic waste products that accumulate in the awake central nervous system (Xie et al., 2013). Obstructive sleep apnea (OSA), for example, is commonly associated with neurocognitive alterations that have not been consistently related to specific abnormalities of brain structure. The neuropsychological results in previous treatment with OSA indicate alterations in the majority of the cognitive areas, and in the state of mind and somnolence. These deficiencies are associated with focal reductions in gray matter volume in the left hippocampus (entorhinal cortex), the left posterior parietal cortex, and the right upper frontal gyrus. However, after treatment, significant improvements are observed related to memory, attention and executive functioning that, in parallel, increase the volume of gray matter in the frontal and hippocampal structures (Canessa et al., 2011). According to these authors, the cognitive and structural deficiencies in OSA may be secondary to sleep deprivation and intermittent nocturnal hypoxemia. These negative effects can be improved with a consistent and complete treatment.

According to a study by Haack and Mullington (2005), insufficient chronic sleep can contribute to the appearance and amplification of pain and affect health by compromising the optimistic perspective and psychosocial functioning. According to Tanaka and Shirakawa (2004), a small nap (30 minutes between 1:00 pm and 3:00 pm) and moderate exercise, such as walking at night, are important for the maintenance and improvement of sleep quality. In their study, mental health improved by improving the quality of sleep. In addition, physical health also improved with the improvement of sleep quality.

In a study conducted by Pilcher, Ginter and Sadowsky (1997) in subjects who slept an average of 7 hours per night, average sleep quality was better related to health, affecting balance, life satisfaction and feelings of tension, depression, anger, fatigue and confusion than the average amount of sleep. In addition, the average sleep quality was better related to sleepiness than the amount of sleep. These results indicate that health professionals should focus on sleep quality in addition to the amount of sleep in their efforts to understand the role of sleep in daily life.

According to Dahl and Lewin (2002), sleep seems to be particularly important during periods of brain maturation. There is also growing evidence that sleep deprivation has its greatest negative effects on the control of behavior, emotions and attention. According to Smaldone, Honig and Byrne (2007), approximately 15 million American children are affected by inadequate sleep, which makes it a relevant issue for children’s health.

In addition, sleep has been considered a way in which the brain strengthens the consolidation of memory after a period of learning (Ekstrand, 1967, Fishbein, 1971, Yaroush, Sullivan, & Ekstrand, 1971). Current literature on the subject abounds with examples of benefits of sleep for memory, in particular, episodic memories has proven to be better after sleep compared to the retention obtained after a waking period (Plihal & Born , 1997; Ellenbogen, Hulbert, Jiang, & Stickgold, 2009). In addition, it has been claimed that sleep could act as a selective tool for the information that will be remembered (for example, Stickgold & Walker, 2013). In general, there seems to be no convincing reason to argue that sleep does not have an effect on the consolidation of memory, given the large amount of literature that supports this fact, however, there is still debate about the scope of this effect and also about how sleep influences the generalization and integration of information.

According to a recent review by Chatburn, Lushington and Kohler (2014), 27 studies were identified in healthy adults that combined indicate a moderate sleep effect to facilitate associative memory as proven behaviorally. These authors interpret these findings as models of associative processing based on reactivation. According to them, sleep facilitates the integration of new information into existing schemes and the extraction of rules and information sets that can be generalized.

Therefore, maintaining a healthy sleep habit of good quality and quantity has a great impact on our health and general well-being.

Nutrition and well-being

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Dietary interventions have emerged as effective environmental inducers of cerebral plasticity. Among these dietary interventions, there is caloric restriction (CR: a constant reduction of the total daily food intake), intermittent fasting (IF) and dietary supplements with polyphenols and polyunsaturated fatty acids (PUFA), all of which have the potential to affect brain plasticity markers in animal studies (Murphy, Dias, & Thuret, 2014). These authors also discuss epidemiological and intervention studies that report the effects of CR, IF and dietary polyphenols and PUFAs on learning, memory and mood. The revised data reinforce the important translational concept that diet, a modifiable lifestyle factor, has the ability to modulate health and brain function.

According to Bourassa, Alim, Bultman and Ratan (2016), the benefits of a diet rich in fiber in the colon have been well documented in epidemiological studies, but their potential impact on the brain has been little studied. The authors review the evidence that butyrate, a short-chain fatty acid (SCFA) produced by the bacterial fermentation of fiber in the colon, can improve brain health. According to the authors, butyrate has been widely studied as an inhibitor of histone deacetylase (HDAC), but it also functions as a ligand for a subset of G protein-coupled receptors and as an energy metabolite. These various modes of action make it suitable for solving the wide range of imbalances that are frequently found in neurological disorders. According to the evidence, they hypothesize that the metabolism of a fiber-rich diet in the intestine can alter gene expression in the brain to prevent neurodegeneration and promote regeneration.

Diet also seems to be an important factor in psychological health, where a vegan diet in particular provides a protective effect. Tsai, Chang and Chi (2012), for example, found frequent consumption of vegetables seems to be protective against depressive symptoms in the elderly. It is worth noting that the intake of fruits, vegetables and antioxidants is lower in older adults with depression, as noted by Payne, Steck, George and Steffens (2012) in their study.

Studies regarding mood and psychological health, such as that of Akbaraly et al. (2009) confirm that dietary patterns have an impact on depressive symptoms. These authors found that after adjusting for potential confounders, participants in the highest tertile of the whole food (plant-based) pattern had lower probabilities of CES-D depression (Center for Epidemiological Studies Depression Scale) than those in the lowest tertile. In contrast, high consumption of processed foods was associated with a higher likelihood of CES-D depression. The authors conclude that in middle-aged participants, a dietary pattern of processed foods is a risk factor for CES-D depression 5 years later, whereas a whole food dietary pattern is protective. In addition, a vegan diet has the potential to increase productivity and quality of life, including the aforementioned mental health. Katcher, Ferdowsian, Hoover, Cohen and Barnard (2010) determined the acceptability of a program of vegan nutrition in the workplace and its effects on quality of life related to health and labor productivity, where the vegan group reported improvements in general health, physical functioning and mental health, vitality and general satisfaction with diet compared to the control group. The vegan group also reported a decrease in food costs and a greater difficulty finding food when they eat out, compared to the control group. The vegan group reported a 40-46% decrease in productivity deficiencies related to health at work and in daily activities.

On the other hand the Omega-6/Omega 3 relatio has a role in mental health. As the authors Vaz, Kac, Nardi and Hibbeln (2014) estimated, the prevalence of suicide risk (SR) and major depressive episode (MDE) in early pregnancy and the relationship of the serum state of fatty acids,it was found that a higher serum status of AA and ADA, two omega-6 fatty acids, were associated with a higher probability of SR and MDE in pregnant Brazilian women regardless of confounding variables.

So a plant-based diet of whole-grain foods (fruits, vegetables, legumes and nuts) is also an important factor that has the potential to have positive effects on our well-being.

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