How does stress impact memory? Why can you remember some details of a stressful event perfectly while completely forgetting others?
In her book Remember, Lisa Genova explores the fascinating relationship between stress and memory. She explains how our brain’s stress response—though vital for survival—can both enhance and impair different aspects of memory formation and recall.
Keep reading to discover how acute and chronic stress affect your memory, attention, and cognitive functioning in surprising ways.
How Stress Impacts Memory
How does stress impact memory? According to Genova, the activation of our stress response can affect our memory in different ways. When we’re stressed, the brain releases stress hormones into our bloodstream. This acute stress response was important for our ancestors to avoid dangerous situations, and it remains necessary for our daily functioning today. Genova explains that modern psychological stress affects us similarly to the physical threats our ancestors faced—the reaction an ancient human would have to being chased by a bear is the same reaction a modern human would have to committing a major social faux pas, for example.
Acute stress has a complex relationship with memory. It enhances the formation of memories related to the stressful situation by increasing attention and activating neurochemical processes that promote memory consolidation. However, this enhancement is selective, focusing on major details of the stressful situation while potentially impairing memory for peripheral details. For example, if you’re hiking in the woods and you encounter a bear, you might remember a lot about the bear’s appearance and behavior (as this is the major source of your stress), but little to nothing about details unrelated to the stressor such as the surrounding landscape.
Additionally, acute stress can interfere with retrieving memories, explaining why you may learn some information thoroughly while stressed but then be unable to remember it later.
| Acute Stress and Executive Functioning Memory is only one of the functions impacted by acute stress. Stress can influence multiple aspects of processing, particularly those related to executive function. This includes working memory, inhibition (the ability to control automatic responses in favor of responses relevant to the stressor), and cognitive flexibility (the ability to shift between different modes of thinking). The theory Genova describes—that stress biases us to attend mostly to information related to the stressor we’re facing—is the most prevalent theory on how stress impacts executive functions. Research into this theory suggests that acute stress tends to impair working memory and cognitive flexibility, but that it actually improves inhibition (which includes selective attention—in this case, the ability to attend to the details related to the stressor rather than irrelevant information). Thus it may be more accurate to say that acute stress enhances attention rather than memory in general. However, some research shows that acute stress can impair all three of these executive functions. To account for this, scientists have formulated another theory: that acute stress shifts your cognitive processing from top-down processes (and executive functions are considered top-down processes) to bottom-up processes. When using top-down processing, the brain takes its existing knowledge and uses it to interpret incoming sensory information. In contrast, bottom-up processing focuses on the incoming sensory information first, leaving higher-level cognitive processes (such as relating it to existing knowledge) for later. This may help us focus on stressors in the moment without being distracted by preconceived biases. |
Genova emphasizes that chronic stress, unlike acute stress, is uniformly detrimental to memory. Persistent stress continuously exposes us to stress hormones, which can desensitize our body’s stress response system and keep it permanently activated. This chronic activation inhibits the prefrontal cortex’s thinking abilities and can actually cause hippocampal neurons to die. And, since the hippocampus is responsible for consolidation, this reduces our capacity to form new memories.
(Shortform note: Research suggests that the chronic stress associated with the Covid-19 pandemic may have impacted many people’s memories. While the viral infection itself is known to impact memory, experts note that even those who weren’t infected faced chronic stressors such as social isolation. This stress increased people’s stress hormone levels, leading to widespread memory issues for people across the world. Studies showed a particularly severe impact on prospective and working memory.)
