Cognitive health
Cognitive health refers to the state of an individual’s cognitive abilities, including memory, attention, reasoning, language, and problem-solving skills. Maintaining cognitive health is essential for overall well-being and quality of life, as cognitive decline can affect daily functioning and lead to conditions such as dementia and Alzheimer’s disease 1.
Stress
The impact of stress on cognitive function, memory, and the role of stress hormones in modulating cognitive health plays a significant role in current society. The concept of stress, however, was first defined by the “father of stress”, Hans Selye, a Hungarian – Canadian endocrinologist back in 1956. Selye defined stress as the non-specific response of the body to any demand placed upon it, which he termed a “stressor.” He proposed that stressors could be both external (e.g., physical threats) and internal (e.g., psychological pressures). The response of the body to these stressors is called the “stress response,” which includes physiological and behavioral changes aimed at adapting to the stressor 2.
Physiology of stress
The physiology of stress is a well-characterized and extensively studied phenomenon in the field of biology and neuroscience. When the body encounters a perceived threat or challenge, it initiates a complex cascade of physiological responses to cope with the stressor. The central player in this response is the hypothalamic-pituitary-adrenal (HPA) axis, a critical neuroendocrine system that coordinates the stress response 19.
Upon encountering a stressor, the hypothalamus, a small region located in the brain, is activated and releases corticotropin-releasing hormone (CRH) into the bloodstream. CRH, in turn, stimulates the anterior pituitary gland, a pea-sized structure located just below the hypothalamus, to release adrenocorticotropic hormone (ACTH)20.
ACTH travels through the bloodstream and reaches the adrenal glands, which are located on top of the kidneys. The adrenal cortex, the outer layer of the adrenal glands, responds to ACTH by releasing glucocorticoid hormones, with cortisol being the primary glucocorticoid in humans20.
Cortisol, a potent stress hormone, plays a pivotal role in orchestrating the body’s response to stress. It mobilizes energy reserves by increasing glucose availability, enhances cardiovascular function to support physical readiness, and temporarily suppresses non-essential bodily functions like digestion and immune response. These actions prepare the body for a fight-or-flight response, enabling it to confront or flee from the stressor21. In parallel with the HPA axis, the sympathetic nervous system (SNS) is also activated during stress. SNS activation leads to the release of adrenaline and noradrenaline, which prepare the body for immediate physical response to the stressor (fight-or-flight response)22.
Once the stressor is resolved, a negative feedback loop operates to restore the body to its baseline state. High cortisol levels signal the hypothalamus and pituitary gland to decrease CRH and ACTH release, respectively, leading to a decline in cortisol production23 (overviewed in Figure 1).
However, chronic stress or ongoing exposure to stressors can disrupt the balance of the HPA axis, resulting in prolonged elevation of cortisol levels. This dysregulation may lead to adverse health effects, including anxiety, depression, metabolic disorders, immune dysfunction, and cardiovascular problems24,25,26.
Adapting to Stress
In 2022, the WHO released a scientific brief that stated the COVID-19 pandemic triggered a 25% increase in the prevalence of anxiety and depression worldwide17. Therefor adapting to stressors has become common practice in modern life. Consumers are now employing various to manage stress-related conditions and promote overall well-being such as using wearable technology with stress management tools3, practicing mindfulness and mediation 4, breathing practices5, physical exercise6, social support and avoiding isolation7, sleep management18 and consuming the correct nutrition8.
Nutrition and Cognitive health
Epidemiological studies, such as the Mediterranean Diet, have shown numerous beneficial outcomes including reduced cardiovascular (CV) risk and prevention of non-communicable diseases (NCDs), which include cognitive decline and dementia. Adherence to the Mediterranean diet and cognitive decline and other dietary interventions are excellently reviewed in8. The Mediterranean diet, which emphasizes whole grains, fruits, vegetables, fish, and olive oil. Therefor elucidation of key components of these epidemiological studies supporting cognitive health are now underway and several have been studied and show to have benefits (see Table 1):
Table 1: Overview of nutrients and their role in cognitive health
Ayurveda is an ancient traditional system of medicine that originated in India more than 5,000 years ago. It is considered one of the oldest holistic healing systems in the world and focuses on balancing the mind, body, and spirit to promote health and prevent disease. Ayurveda extensively uses herbal remedies derived from plants, minerals, and other natural substances. These herbs or botanicas are believed to have specific properties that can balance the doshas and promote healing27.
Both the modern medical literature and traditional Ayurveda writings report many potential health benefits of the Ashwagandha herb (Withania somnifera, also known as Indian Ginseng or Winter Cherry under the rubrics of anti-stress, neuroprotective effects, immunomodulatory effects and rejuvenating effects, via the herd’s interplay with the nervous system, the endocrine system, the cardiopulmonary system, the energy production system and the immune system including analgesic, antimicrobial, anti-inflammatory, anti-tumor, anti-stress, anti-diabetic, neuroprotective, immune-protective and cardio-protective effects.27-32. This literature has only a small set of published papers, which is surprising because traditional Ayurveda explicitly advocates the use of Ashwagandha toward “Bala”, which means “strength” in the Sanskrit language28,29.
Ashwagandha (Withania somnifera) is a member of the family of herbs referred to as “adaptogens”. The term adaptogen was introduced into scientific literature by Russian toxicologist Nikolay Lazarev in 1957 to refer to substances that increase the “state of non-specific resistance” in stress. The term “adaptogen” is applied to an herb with phytonutrients that regulate metabolism when a body is perturbed by physical or mental stress and help the body adaptation30. The adaptogen family of herbs has many members, noteworthy among them being Ashwagandha, rhodiola, ginseng, schisandra and maca. Adaptogens are used commonly for stress relief, brain health and for ameliorating HPA-axis dysfunction. More recently, adaptogens have started to be used in sports supplements that aim to enhance physical fitness31,32.
Ashwagandha is classified as a “rasayana” (rejuvenator and have been used toward promoting health and longevity, slowing the aging process, revitalizing the body and generally creating a sense of well-being33. It also stimulates respiratory function, causing smooth muscle relaxation and stimulates thyroid activity34. Studies in humans show that Ashwagandha is well tolerated and is associated with decreases in cortisol35 and increases in testosterone36.
There are a number of biochemical parameters that are indicators of activation of the stress response, such as salivary alpha-amylase, an important enzyme in the oral cavity that has been proposed as a potential marker of sympathetic activation and rises in response to prolonged stress. Exposure to stress activates the autonomic nervous system and increases sympathoadrenomedullary drive, which causes a widespread reaction that can stresses in the face of challenges. Numerous additional systems, such as the pro-inflammatory cytokines interleukin-1β, interleukin-6, and tumour necrosis factor-α, also have temporal connections to stressful events34.
Sleep disorders and stress are related. The central nervous system and metabolism are both impacted by the bidirectional link between stresses and sleep disorders. High levels of stress hormones are connected to shorter sleep duration, while obesity and metabolic syndrome are both associated to stress and sleep-related issues. Common sleep disorders include insomnia (difficulty falling and/or staying asleep), hypersomnia (excessive daytime sleepiness), and sleep apnea (airflow is limited while sleeping, causing low oxygen saturation and disrupted sleep). Stress can cause insomnia and be the result of it, thereby explaining the positive association between stress and insomnia that is often observed. In general, stress alone had a stronger association with mental health problems than sleep disorders alone, and the combination of stress and sleep disorders had the strongest association.
