Compulsive behaviors are linked to conditions like obsessive-compulsive disorder (OCD), substance use, gambling, and other addictions, and are often described as habits that take over and override conscious control.
However, new research suggests this may not always be the case. In a recent study published in Neuropsychopharmacology, researchers from the University of Technology Sydney (UTS) found that inflammation in a key decision-making region of the brain led to more deliberate behavior, rather than more compulsive actions. These findings challenge the traditional ‘habit loop’ model of compulsion.
Rethinking the Habit Loop Hypothesis
The main idea of the habit loop hypothesis is that repeating certain actions turns them into habits, which then take over from conscious, goal-driven choices. In this model, people continue harmful behaviors because the actions become automatic.
Researchers at UTS set out to test this idea. Previous brain imaging studies have shown that people with compulsive disorders often have inflammation in the striatum, a brain region involved in selecting and evaluating actions. The team wanted to test whether increasing striatal inflammation would make behavior more habit-driven. To do this, they induced inflammation in the striatum of rats and examined how the animals learned and adjusted their actions.
Inflammation Increased Deliberate Control
The results did not match the researchers’ expectations. Instead of acting impulsively, rats with striatal inflammation demonstrated more goal-directed behavior. They continued to adjust their actions based on situational outcomes, even when habits would normally take over.
“Surprisingly, the animals became more goal-directed and continued to adjust their behavior based on outcomes, even in situations where habits would normally take over,” said senior author Dr. Laura Bradfield, a behavioral neuroscientist at UTS. This suggests that inflammation did not reduce cognitive control; rather, it strengthened it.
Astrocytes Disrupt Local Circuits
The researchers connected this behavioral change to astrocytes, star-shaped support cells that help regulate neural activity and maintain brain balance. When inflammation increased, astrocytes multiplied in the striatum and disrupted nearby neural circuits involved in movement and decision-making.
Astrocytes do not transmit electrical signals like neurons do, but they shape the environment in which neurons function. When astrocytes multiply and change circuit activity, they may affect how the brain processes decisions. These findings suggest that, at least in this model, compulsive behavior may not arise from a loss of control but from an over-engaged decision system.
A New Perspective on Compulsion
This shift in perspective could influence how clinicians understand and approach compulsive disorders.
“There’s a lot of compulsive behavior that doesn’t fit neatly into the habit hypothesis,” Bradfield said. “If someone is continually washing their hands because they are worried about germs, they are not doing this without thinking, they are consciously choosing to make that effort.”
Some compulsive behaviors may result from too much deliberation. In these cases, people repeatedly evaluate outcomes but do not resolve their uncertainty. The researchers suggest that targeting astrocytes or reducing neuroinflammation could offer a new direction for treatment. Broader anti-inflammatory strategies, such as improving sleep or increasing exercise, may also affect these brain pathways.
Important Caveats
Although the striatum plays a similar role in action selection in different species, complex psychiatric conditions like OCD involve many brain networks and experiences that animal models cannot fully capture.
The researchers also induced inflammation in a controlled manner, which may not reflect the long-term, complex inflammation seen in people. More studies are needed to see if similar astrocyte-driven changes happen in humans with compulsive disorders.
Compulsion may not always indicate a loss of control. In some cases, it could reflect control systems working too hard, with the brain repeatedly recalculating outcomes in inflamed neural circuits.
As neuroscientists continue to study how immune signals affect brain function, research like this suggests that inflammation does more than disrupt thinking. It may change the balance between habit and deliberation, which could influence how compulsive disorders are understood and treated.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds a Master of Business Administration, a Bachelor of Science in Business Administration, and a Data Analytics certification. His work combines analytical training with a focus on emerging science, aerospace, and astronomical research.