Brain inflammation may drive compulsive behavior, rat study suggests

Compulsive behavior may not be a runaway habit

Compulsive behavior may be caused by excessive deliberate control rather than a loss of control to habit, according to new research in rats. The study, from the University of Technology Sydney, challenges the long-held "habit loop" theory of conditions like OCD and addiction.

Senior author Dr. Laura Bradfield said the prevailing view is that compulsive actions become so automatic they override conscious thought. "However, if we are driving and a child steps onto the road, we suddenly become aware and adjust," she said. "That's taking back control."

An inflammation experiment yielded a surprise

The research team, led by Dr. Arvie Abiero, induced inflammation in a part of the rat brain called the striatum. Brain scans often show inflammation there in people with compulsive disorders.

The scientists expected this to make the rats more habitual. Instead, the opposite happened. "Surprisingly, the animals became more goal-directed," said Dr. Bradfield. They continued adjusting their behavior based on outcomes, even in situations designed to promote habit.

Star-shaped brain cells are the key

The team traced the effect to astrocytes, star-shaped support cells in the brain. When inflammation was triggered, these cells multiplied and disrupted nearby neural circuits for movement and decision-making.

This suggests the problem isn't a runaway autopilot. "If someone is continually washing their hands because they are worried about germs, they are not doing this without thinking," Dr. Bradfield said. "They are consciously choosing to make that effort."

The findings point to new treatments

The study, published in Neuropsychopharmacology, offers a new explanation that could lead to different therapies. Treatments might target astrocytes or reduce neuroinflammation directly.

Broader anti-inflammatory strategies could also help. The researchers point to options like:

• New medications aimed at astrocyte activity
• Therapies to reduce brain inflammation
• Lifestyle interventions including regular exercise and improved sleep

"Our findings offer a new explanation for these behaviors, which goes against the accepted view," said Dr. Bradfield. "It's possible that new treatments and interventions can be developed that more effectively treat these diseases and disorders."