Whether transient or long-lasting, the physiological response to stress impairs memory, causing difficulty in retaining new information and retrieving already established memories.
however, the effects of stress on memory can be somewhat contradictory and differ depending on whether we are talking about acute or chronic stress.
Relationship between stress and memory loss
When the demands of the situation we find ourselves in exceed our physical and / or cognitive capacities, our body activates the stress response. This involves the release of glucocorticoids, stress hormones, into the bloodstream.
Glucocorticoids have different effects on the body, including increased heart and respiratory rates, reduced gastrointestinal activity, and the release of stored glucose stores for use as an energy source.
If your concentration of glucocorticoids is excessive, among which cortisol stands out, they can have a negative effect on the functions of the hippocampus, a brain structure associated with the formation and retrieval of memories. This is in part due to the fact that glucocorticoids redirect glucose from the hippocampus to nearby muscles.
Two types of stress have been described according to their origin: extrinsic and intrinsic. Extrinsic stress is caused by non-cognitive factors, such as those arising from a particular situation, while the intrinsic is related to the level of intellectual challenge that a task requires. Some people have chronic intrinsic stress.
Stress interferes with both our ability to retain new information and to retrieve memories and knowledge, causing memory loss. Additionally, extrinsic stress appears to affect spatial learning. In the following sections, we will describe these effects in more detail.
Yerkes-Dodson’s law: the inverted O
Yerkes-Dodson’s Law states that stress does not always negatively interfere with cognitionBut a moderate degree of brain activation improves memory and performance in intellectual tasks. In contrast, an excessive increase in stress levels worsens cognitive functions.
This gives rise to what is called the “inverted U effect”: if our body responds to environmental demands with responses to mild or moderate stress, the efficiency of our productivity increases until it reaches a threshold (the site of ‘ideal activation) from which performance gradually decreases and memory loss occurs.
Too intense stress responses interfere with the performance of intellectual tasks because they are associated with physical and cognitive symptoms such as difficulty concentrating, tachycardia, sweating, dizziness or hyperventilation.
Effects of acute or transient stress
When we are in a stressful situation, our attention is focused on the most outgoing stimuli, while we pay less attention to the rest; this phenomenon is known as “tunnel vision” and makes it easier to consolidate some memories while interfering with others, leading to memory loss.
Acute stress can have beneficial effects on certain types of memory, but only under certain conditions. In this sense, it is necessary to mention again the law of Yerkes-Dodson; On another side, some studies have shown that glucocorticoids improve the formation of new memories but they worsen the recovery of other existing ones.
Additionally, emotionally relevant stimuli are better remembered if the stress response has occurred before, information retrieval takes place soon after coding, and the memory situation is similar to that of learning.
Other research suggests that under stressful conditions we learn and remember more about information and situations that cause us emotional distress. This fact is associated with the mood congruence effect described by Gordon H. Bower, who describes similar findings in relation to depression.
Consequences of chronic stress
The stress response not only causes changes in memory as it occurs, but if maintained chronically, it can cause long-term damage to the brain. Since the body consumes many resources and reserves to activate these physiological processes, chronic stress is significantly more harmful than acute stress.
After acute or transient stressful situations, our body regains homeostasis, that is to say physiological balance; on the contrary, chronic stress prevents the body from regaining its homeostasis. Therefore, if stress persists, it imbalances the body’s responses.
From a physiological point of view, this facilitates symptoms such as abdominal, back and head pain, chronic difficulties in concentrating and reconciling or maintaining sleep, anxiety attacks, etc. Additionally, ongoing stress is associated with social isolation, depression, and the development of cardiovascular disease.
When it comes to memory loss, chronic stress increases the risk of dementia in older people. These effects are probably related to the activity of glucocorticoids in the hippocampus and in other areas of the brain on which memory and cognition in general depend.