How stress affects the brain: Hippocampus

Stress is often talked about as something we “feel”, but biologically, it is something the brain does.

The brain initiates a hormonal cascade that releases cortisol, the body’s main stress hormone, where we are under pressure.

In short bursts, cortisol can be extremely useful. It sharpens focus, boosts energy availability and helps us respond quickly to challenges. However, cortisol starts to affect the structure and function of the brain, when stress persists for an extended period of time. This negatively affects the hippocampus in particular, which is in charge of learning, memory, and emotional control.

Since the hippocampus has a large number of glucocorticoid receptors, it is particularly

sensitive to cortisol. These receptors assist the brain in tracking our level of stress and

indicating when the body should return to a relaxed state. Nonetheless, these receptors are

overloaded by the continuous flood of cortisol during chronic stress. This may eventually interfere with the hippocampal formation and retrieval of memories.

Long-term cortisol exposure has been shown to weaken synaptic connections, decrease the production of new neurons in the hippocampus, and even cause a discernible reduction in hippocampal volume. This explains why memory loss, difficulty focusing, or feeling mentally “foggy” are common symptoms of long-term stress.

These neural changes do not all happen at once. They build slowly as stress becomes a daily

norm rather than an occasional experience. When the hippocampus becomes less effective at regulating stress signals, the brain enters a loop where stress becomes self-sustaining;

cortisol interrupts normal functioning, which leads to more stress, producing more cortisol.

This cycle can make small challenges feel overwhelming and can reduce the brain’s capacity to learn new information or adapt to changing situations. The result is not just feeling stressed, but thinking and living in a stressed-state.

Despite how sensitive the hippocampus is to cortisol, it is also one of the most adaptable

regions of the brain. Neuroplasticity allows damaged or weakened neural connections to repair themselves when stress decreases.

Daily habits such as quality sleep, mindfulness practices and intellectually stimulating activities all support the release of growth factors like BNDF, which help the hippocampus recover. Simple routines such as short walks and social connection can shift the brain back toward healthy neurorecognition. The hippocampus’s reaction to stress can also be measured in relation to mindset. When one approaches challenges with curiosity instead of fear, the prefrontal cortex is activated more, which promotes flexible thinking, and less cortisol is released. Reframing eros as a necessary part of learning facilitates the brain’s transition from threat-based to growth-oriented pathways. This change not only makes the hippocampus feel better, but it also improves its biological

environment.

Although stress cannot be avoided, the importance of balance, rest and deliberate habits can be better understood by considering how cortisol interacts with the hippocampus. Stress does not passively mold the brain. However, it continuously adapts, heals and rebuilds itself. Even after extended periods of pressure, it can regain strength and function under the correctcircumstances. It is simpler to take a step back, take a breath, and help the brain to do what it is designed to do - adapt - when you know what is going on beneath the surface.

By: Laura Merrin