What does prolonged stress do to your memory?

Prolonged stress damages two brain regions that are indispensable for memory: the hippocampus and the prefrontal cortex. In animal research, nerve cells in those regions shrink, synaptic connections are lost, and the animals displayed memory impairment and depression-like behaviour. A similar pattern has been described in humans, although the causal evidence in humans is less direct than in animals.

How exactly this works is partly understood. Chronic stress disrupts the balance between two neurotransmitters in the prefrontal cortex: glutamate (the 'accelerator') and GABA (the 'brake'). That disruption undermines the flexibility of connections between nerve cells, which translates into difficulty with working memory, decision-making and the regulation of emotions.

The largest epidemiological study cited followed more than 17,000 people and showed a clear dose-response relationship: the more severe adverse childhood experiences a person had gone through, the higher the risk of memory problems in adulthood. That stepwise pattern is a strong associative signal, although it does not prove a direct cause.

Stress also has indirect routes to memory problems. Sleep disturbances and concentration difficulties are part of the broader picture of chronic stress, although those links have not been worked out mechanistically in the available studies. With traumatic stress (such as in PTSD) something else is also at play: in addition to consciously accessible memories, automatically activated memories can arise that are triggered by environmental cues and manifest as flashbacks. That is a theoretical model with limited direct empirical testing so far.

There is little concrete to say about supplements. For plant-based adaptogens such as Panax ginseng and Rhodiola rosea, clinical studies in humans are too scarce to conclude that they counteract stress-related memory problems.