Biology
The Effects of Chronic Stress on Hippocampal Neurogenesis and Memory
Quick fact
Prolonged stress can actually shrink the hippocampus, a brain region critical for forming new memories, and it reduces the birth of new neurons by up to 50% in some brain areas.
Why this is interesting
Have you ever felt so stressed that you couldn't remember where you put your keys? Chronic stress does more than that—it physically changes your brain's memory center.
Read the full explanation
Understanding The Effects of Chronic Stress on Hippocampal Neurogenesis and Memory
Think of your brain as a garden. New neurons are like fresh sprouts that keep the garden healthy and adaptable. In a part of the brain called the hippocampus, new neurons are born throughout life—this is neurogenesis. But chronic stress is like a harsh drought: the stress hormone cortisol floods the garden, stunting growth and even killing existing plants. When neurogenesis slows down, the hippocampus becomes less efficient at forming new memories and recalling old ones. So, when you're constantly stressed, your brain loses its ability to keep your memories sharp.
A deeper explanation
The mechanism involves the hypothalamic-pituitary-adrenal (HPA) axis, which releases cortisol in response to stress. Normally, cortisol helps the body cope and then returns to baseline. But with chronic stress, cortisol stays elevated, overstimulating glucocorticoid receptors in the hippocampus. This overactivation suppresses the expression of brain-derived neurotrophic factor (BDNF), a protein essential for neuron growth and survival. Reduced BDNF leads to lower rates of neurogenesis, impairments in synaptic plasticity (how neurons strengthen their connections), and eventual dendritic retraction in hippocampal neurons. As a result, the hippocampus struggles to encode new memories and retrieve old ones, and it also loses its ability to regulate the stress response—creating a vicious cycle. This mechanism is central to understanding how stress contributes to memory decline, depression, and anxiety, and highlights why stress management is critical for cognitive health.