Compulsive behaviour: Compulsive behaviours may be driven by inflammation in a decision-making hub of the brain, rather than a “habit loop” overpowering self-control, according to a new rat study that challenges a long-standing explanation for disorders marked by repetitive actions despite harmful consequences.
Compulsions, such as repeated handwashing, checking rituals, or persistent gambling, are often framed as habits that become so entrenched they take over on “autopilot,” making it difficult to switch back to conscious, flexible control.
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The new research points to a different possibility: in some cases, the problem may not be too much habit, but misdirected action control linked to neuroinflammation.
The study, published in Neuropsychopharmacology, tested what happens when inflammation is triggered in the dorsomedial striatum, a region involved in selecting actions, motivation, and the balance between habit-driven and goal-directed behaviour.
Researchers induced inflammation in this part of the striatum in rats and then assessed how the animals made choices in situations where habits would typically dominate.
Instead of becoming more habitual, the rats showed the opposite pattern. They remained highly goal-directed, continuing to adjust what they did based on outcomes, even under conditions that usually produce automatic, habit-like responding. In other words, inflammation did not “lock” behaviour into a rigid habit loop; it appeared to bias the system toward excessive, effortful control.
Laboratory analysis linked this shift to changes in astrocytes, star-shaped support cells that help maintain the brain’s chemical environment and influence how nearby neurons function. Inflammation led to astrocyte proliferation and disruption in how neighbouring neurons fired, particularly circuits that help coordinate movement and decision-making. The researchers suggest this astrocyte-related disruption may be a key mechanism explaining why action selection became unusually goal-focused rather than habitual.
The findings raise the possibility that at least some compulsive behaviours could be better understood as maladaptive goal-directed actions, repeated behaviours that feel necessary or “correct” despite negative outcomes, rather than simple habit dominance. If similar biology holds in humans, it could open the door to new approaches that focus on reducing neuroinflammation or targeting astrocyte dysfunction, alongside broader measures that lower inflammatory load, such as better sleep and regular physical activity.
Researchers cautioned that the work is based on an animal model, but said it offers a fresh direction for understanding compulsive disorders and why breaking repetitive behaviour patterns may not always be as simple as “overriding habits.”
