The article ‘Chronic stress, cognitive functioning and mentalhealth’ by Marin (2011) and colleagues is one of many scholarlypapers that address the issue of stress and its impact on mentalhealth. The paper was published in a peer reviewed journal, theNeurobiology of Learning and Memory, in 2011. The paper pickson one of the four types of stress (acute stress, episodic acutestress and chronic stress), chronic stress, with a view to show howthis particular type of stress affects the cognitive and mentalhealth functioning of individuals and also show how the majorstress-related disorders such as burnout, depression, andpost-traumatic stress disorder come into the picture. The paper doesnot present the findings of a primary study but rather it is asystematic review on studies on the said topic area. The study provesthat diagnosis of chronic stress is not only important in treatingmental health and cognitive functioning problems, but is alsocritical to understand the risk factors and the particular contextindividuals face that predisposes them to the condition thatemphasizes on the psychological approach in managing stress.
The paper starts out with a very informative and well researchedintroduction. In this section, the authors provide key basicinformation on the genesis of stress from a neurological point ofview. It indicates that stress is caused by a class of hormonescalled Glucocorticoids (GCs) that are released into the system onceindividuals are exposed to stressful impetuses. These impetuses couldbe stressful situations or events whose degree of influence intriggering the release of GCs varies. This is to mean that a singlesituation can draw different biological or hormonal reactions fromdifferent individuals. Where a situation proves to be a stressfulstimulant, GCs (mainly cortisol in humans and corticosterone inanimals) are released, courtesy of the hypothalamic–pituitary–adrenal(HPA) axis. This process involves several steps. First, the HPA axisis activated by the release of corticotropin-releasing factor (CRF)from the hypothalamus. The CRF then triggers the release ofadrenocorticotropin hormone (ACTH) from the anterior part of thepituitary gland. The ACTH is then released into the blood streamwhere it travels to the receptors on the adrenal glands located abovethe kidneys. These glands release the GCs which are then transportedto GCs receptors located all over the brain. There are two types ofthe mineralocorticoid receptor (MR or Type I) and theglucocorticoid receptor (GR or Type II).
The HPA axis is controlled by the three organs the amygdala, thehippocampus and the medial prefrontal cortex. The amygdala triggersthe HPA process while the other two inhibit the process. The amygdalais particularly known to detect fear thus triggering the HPA axis.Nonetheless, it is the hippocampus that plays the greatest role inthe whole process for three main reasons. One it is capable ofinhibiting the process, two because it contains both types of GCreceptors and third because it is associated with stress relateddisorders such as depression, Alzheimer’s Disease (AD) andpost-traumatic stress disorder (PTSD). Chronic stress thus manifestsitself after prolonged presence of GCs which is diagnosed as mentalhealth and cognitive problems
Although age plays a key role in influencing cognitive and mentalfunctioning, it is not the only determinant. Studies have shown thataged persons record higher levels of GCs meaning that they are mostvulnerable to mental health and cognitive problems. Similarly,prolonged and continued administration of GCs to middle-aged ratsshowed a similar loss in spatial memory, which is controlled by thehippocampus, to aged rats. Alternatively, inhibition of the HPA axisto reduce secretion of GCs in aging rats had the opposite effect inthat there was improved spatial memory functioning. This research isknown as the ‘neurotoxicity hypothesis.’ It conjectures thatprolonged exposure to GCs negatively affects the HPA axis and ineffect the hippocampus leading to poor mental health. However, asearlier stated, GCs secretion in response to a given stimuli, varieswidely in humans. Could this mean that some individuals facepathological aging as a result of prolonged exposure to GCs?
It is premature to clearly state the role of cortisol on predictingpathological aging. Several studies have been performed on elderlypeople, both healthy and suffering from AD, with mixed results. Somehave shown that higher cortisol levels were positively correlatedwith cognitive decline (risk of developing of AD). Other studiesregistered a negative correlation between cortisol levels andcognitive decline. The allostatic load concepthas been used to explain this ambiguousness. This concept states thatin general aging, chronic stress exerts cumulative stress on themetabolic, immune, neuroendocrine and cardiovascular systems makesindividuals more vulnerable to stress related problems (Dismadale,2008). This negative effectprogresses with age up until 60 years when it stagnates. Forpsychologists, this implies that mental health problems especiallyones that occur later in life are manifestations of physiologicaldysregulations that commenced decades ago. Such physiologicaldysregulations could be due to depression and burnout in theworkplace, early life adversity, genetics, sex hormones, andpost-traumatic stress disorder.
There are no current studies that have comprehensively investigatedthe link between biological signatures and cognitive impairment ordecline. Current knowledge however, shows that cognitive impairmentin adulthood interacts strongly with biological activities of thepast, present and future. The key link between mental health andworkplace burnout and other biological and environmental contexts isthat chronic distress triggered by the specific contexts or stimulioverwhelms the psychological capacities of an a individual thatincreases their susceptibility to mental health issues. PTSD has alsoplayed its part in the development and risks of mental health studieshave shown that PSTD diagnosed individuals react in a greater waywhen exposed to stimuli than other individuals. This suggests thatsuch conditions can lead to over secretion of GCs putting theindividual at great risks of developing more complex mental healthissues.
Sexual and genetic makeup of individuals also influences how theyrespond to stressor stimuli. Studies have shown that men display ahigher cortisol response than women to the same stimuli. Thisvariation in response is also found in age-specific differences. Thegendered differences are explained by the two distinct endocrinemilieus of women and men. This implies that different levels ofgendered hormones, testosterone and estrogen, which are agedetermined will influence how difference sexes at different ages willreact to stressor stimuli. Other condition such as menopause andpregnancy are also likely to impact reaction of stressor stimuli andthe degree of cortisol secretion. The same case applies to familygenes. Studies among twins from high adversity and low adversityfamilies showed different levels of cortisol secretion of exposurestimuli. Twins from high adversity families showed a higher cortisolreaction. Other than this early life adversities play a role.
Psychologists have always been interested in individuals’ childhoodevents. In fact psychologists believe that one childhood affectsone’s adulthood (Walsh, 2011). In this regard, early lifeadversities such as poor parenting or abuse affect theneurodevelopment of these children and program them to react tocertain stressors in a certain way. Studies in rodents have shownthat disruptive and fragmented involvement with the dam at an earlyage impairs learning and memory functions dependent on thehippocampus. Alternatively, improved neonatal handling and displayedenhanced learning and memory capabilities displayed improved memoryand cognitive functioning.
This systematic analysis by Marin and colleagues gives irrefutableevidence that chronic stress, as one of the key disorders thatpsychologists have to deal with, has a broader neurological,physiological and environmental basis than previously thought. Infact, chronic stress comes out as a potential accelerator and/oramplifier of definite pre-existing vulnerabilities. Therefore, thiscalls for psychologists to address the causal factors of stressrather than deal with a symptom. It is also clear that stress, incombination with genetic and environmental factors, poses a very hugerisk to mental and cognitive health that psychologists must beprepared to deal with. The unique experiences and contexts thatindividuals face require a contextualized psychological approach inmanaging their stress issues.
Dismadale, J.(2008). Psychological stress and cardiovascular disease. Journalof the American College of Cardiology 51(13) 1237–1246.
Marin, M., Lord,C., Andrews, J., Juster, R., Sindi, S. et al. (2011). Chronic stress,cognitive functioning and mental health. Neurobiology of Learningand Memory 96(4) 583–595.
Walsh, R. (2011). Lifestyle and mental health. The American Psychologist,66(7) 579-592