🧠 Depression May Disrupt the Adult Brain’s Ability to Make New Neurons

For decades, scientists have suspected that depression may interfere with neurogenesis — the formation of new neurons in the adult hippocampus. Most of the strongest evidence, however, came from animal studies.

Now researchers have found evidence of the same process directly in human brains.
The team analyzed nearly 500,000 individual cell nuclei from hippocampal tissue donated by people with major depressive disorder and people without psychiatric illness. Using single-cell gene sequencing, chromatin analysis, spatial transcriptomics and protein measurements, they reconstructed what is effectively a molecular atlas of the hippocampus.
They found a lineage of cells consistent with ongoing adult neurogenesis — but in people with depression, that developmental process appeared to stall before new neurons fully matured. The surrounding hippocampal circuitry also showed signs of inflammation, cellular stress, disrupted synaptic plasticity, altered metabolism and an imbalance between excitatory and inhibitory signaling.

The finding could help explain something particularly characteristic of depression: the tendency for negative memories and experiences to dominate. New hippocampal neurons are thought to contribute to pattern separation — our ability to distinguish a new experience from similar memories in the past.
There is an important caveat: this study shows an association in post-mortem human brains. It does not prove that reduced neurogenesis causes depression, nor does it mean simply increasing neuron production would cure it.

But it moves one long-standing theory of depression from animal experiments much closer to human biology.
Depression may not simply change how neurons communicate.
It may change how the brain renews itself.


#Neuroscience #Depression #Brain #Neurogenesis #MentalHealth #Science
https://www.nature.com/articles/s41591-026-04571-8