Determining Cortisol's Influence on Memory Requires Future Research

The glucocorticoid (GC) known as cortisol is secreted from the adrenal gland when someone is exposed to stress from their internal or external environment. Cortisol modulates various physiological functions during stress to help one adapt; however, it also has an effect on cognitive functions. One cognitive function affected by cortisol, with an increasing interest among scientists, is memory. Various experiments conducted with the goal in mind of finding cortisol‟s effect on memory, yield contradictory results. Some of the experiments show that cortisol weakens a person‟s ability to retrieve emotional memory, and enhances their ability to retrieve neutral (Kuhlmann et al., (2005); Tollenaar et al., (2008). Others show cortisol enhances a person‟s ability to retrieve emotional memory, and impairs their ability to retrieve neutral (M. Jelicic et al., (2004); P. Putman et al., (2004). This review paper focuses on analyzing these experiments and their results, to help expose methodological flaws and, as a consequence, give insight on how to improve future experiments to achieve more valid results. This collective analysis further corroborates the complex functioning of cortisol and how it affects one‟s ability to recall information of varying emotional valence while undergoing different levels of stress. Introduction When a person is exposed to stress from their internal or external environment, glucocorticoids (GC) known as cortisol are secreted into the bloodstream from the adrenal gland. When cortisol binds to glucocorticoid receptors (GR), it helps the person adapt to stress (De Kloet et al., 1998). While cortisol modulates the physiological changes associated with adapting to stress, e.g., accelerated carbohydrate metabolism, blood pressure, and heart rate, it also affects cognitive functions (De Kloet et al., 1999; Rozendaal, 2002). Scientists are conducting experiments to find the relationship between increased cortisol and cognitive functions, and yielding variable results. Memory, for example, seems to be the most controversial. Most of the studies on cortisol‟s influence on memory focus on how stress and cortisol affect emotional memory versus neutral memory. Some of the experiments show that cortisol impairs a person‟s ability to retrieve emotional memory, and enhances their ability to retrieve neutral memory (Kuhlmann et al., (2005); Tollenaar et al., (2008). Others show cortisol enhances a person‟s ability to retrieve emotional memory, and impairs their ability to retrieve neutral memory (M. Jelicic et al., (2004); P. Putman et al., (2004). The experiments testing for the correlation between cortisol and memory show contradictory results, and the validity of each of these experiments is open for interpretation. These experiment‟s validity need to be addressed because of the possible implications they have on causes of diseases like Alzheimer‟s Disease, and Parkinson„s Disease--diseases which are suggested to be associated with hyper-cortisolism (Hartmann et al., 1996). Future, valid experiments are needed to eliminate the confusion regarding cortisol‟s effect on memory. This review paper‟s main focus is to compare the current experiments and their results that test for cortisol‟s influence on memory and underscore the complex functioning of cortisol as it affects memory. Analyzing these experiments and their results will help to expose their flaws and, as result, give more insight on how to conduct future experiments that have valid results.