Anxiety affects about one in five people in the United States, but the brain mechanisms that start anxiety are not fully known. New work at the University of Utah, published in Molecular Psychiatry, points to an unexpected role for microglia, a class of immune cells that live in the brain.
Many researchers previously assumed microglia act similarly. Earlier experiments showed that blocking Hoxb8 microglia made mice act anxious, yet blocking all microglia at once left mice behaving normally. This paradox suggested different microglia types might have opposite functions. To investigate, the team used mice without microglia and transplanted either Hoxb8 microglia, non-Hoxb8 microglia, or both, allowing each population to be observed on its own.
The findings were clear: non-Hoxb8 microglia acted like an accelerator for anxiety, producing compulsive grooming and less time in open spaces. Hoxb8 microglia did not cause anxiety, and the presence of both types produced normal behaviour, indicating a balance. The senior author, Mario Capecchi, said the two populations together set appropriate anxiety levels for the mouse's environment, and Donn Van Deren called the result a paradigm shift.
The team points out that humans also have two similar microglia populations. Most psychiatric drugs target neurons, but these results suggest an alternative: therapies that change microglial activity by activating anxiety-preventing cells or weakening anxiety-promoting cells. Researchers caution treatments are not near-term, though future pharmacological or immunotherapeutic methods might target specific brain immune cells. Support for the work came from the National Institutes of Health, including the National Institute of Mental Health, the Dauten Family Foundation, and the University of Utah Flow Cytometry Facility.
Difficult words
- microglia — immune cells that live inside the brain
- immune cell — a cell that helps fight infection or injuryimmune cells
- transplant — move cells or tissue into another bodytransplanted
- compulsive grooming — repeated, uncontrollable cleaning of the body
- accelerator — something that increases a process or activity
- balance — a state where different forces act evenly
- paradigm shift — a big change in how people understand something
- therapy — treatment to improve health or reduce symptomstherapies
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What are possible advantages and risks of targeting microglia instead of neurons to treat anxiety? Give reasons from the article.
- How might the idea of a balance between two cell populations change the way we think about mental health treatments?
- What steps should researchers take before trying microglia-targeting therapies in humans, based on the article?
Related articles
Africa uses AI to strengthen health systems and self-reliance
At the CPHIA conference in Durban, Africa CDC said AI and digital tools can help protect 1.4 billion people, improve surveillance and support primary health care. Data governance, infrastructure and domestic financing are key concerns.
Clock disruption speeds breast cancer in models
New research finds that repeating disruption of the body’s 24-hour clock changes breast tissue, weakens immune defenses and leads to faster, more aggressive breast cancer in experimental models. The study links altered light–dark schedules to worse outcomes.
Forest loss in tropics raises local heat and deaths
A study using satellite data found that tropical deforestation from 2001–2020 exposed 345 million people to local warming and likely caused about 28,000 heat-related deaths per year, mainly in Africa, Southeast Asia and Latin America.
