For years, scientists have believed that compulsive behaviors happen when people become trapped in a "habit loop" that overrides self-control. But new research in rats from the University of Technology Sydney (UTS) suggests the story may be more complicated.
Compulsive behaviors appear in a range of mental health conditions, including obsessive-compulsive disorder, substance use disorders, and gambling disorder. In these conditions, people continue repeating certain actions even when they lead to harmful consequences. Millions of people worldwide are affected.
How Habits and Self-Control Normally Work
Senior author Dr. Laura Bradfield, a behavioral neuroscientist, explained that habits serve an important purpose. They allow us to run on autopilot during routine tasks like brushing our teeth or driving along a familiar road, freeing up mental energy for other thoughts.
"However, if we are driving and a child steps onto the road, then we suddenly become aware of our surroundings and focus on what we are doing. This involves taking back conscious control, thinking about possible outcomes and adjusting our behavior," said Dr. Bradfield.
In compulsive behaviors such as repeated handwashing or playing poker machines, the prevailing theory has been that these actions become deeply ingrained habits. According to this view, the behavior runs automatically, making it hard for people to regain cognitive control.
"Brain imaging studies show it's common for people with compulsive disorders to have inflammation in the striatum, a brain region involved in choosing actions, so we decided to test whether inducing inflammation in this region in rats would increase habitual behavior."
Brain Inflammation and Decision-Making
The study was led by Dr. Arvie Abiero during his PhD research at UTS and was recently published in Neuropsychopharmacology. The researchers examined how rats learn behaviors and how they regulate their actions. When inflammation was triggered in the striatum, the results were unexpected. Instead of becoming more automatic or habit-driven, the rats showed more deliberate and effortful decision-making.
"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 Dr. Bradfield.
The Role of Astrocytes in Compulsive Behavior
The team traced these changes to astrocytes, star-shaped cells in the brain that support neurons. When inflammation occurred, astrocytes multiplied and disrupted nearby neural circuits that control movement and decision-making.
These findings could have important implications for psychologists, psychiatrists, patients, and caregivers who work with compulsive disorders. Rather than reflecting a loss of control due to runaway habits, some compulsive behaviors may result from excessive, though misdirected, deliberate control.
The researchers suggest that medications aimed at astrocytes or treatments that reduce neuroinflammation may provide new therapeutic options. Broader anti-inflammatory strategies, such as regular exercise or improved sleep, could also play a role.
"There's a lot of compulsive behavior that doesn't fit neatly into the habit hypothesis. 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," said Dr. Bradfield.
"Our findings offer a new explanation for these behaviors, which goes against the accepted view. Based on this, it's possible that new treatments and interventions can be developed that more effectively treat these diseases and disorders," she said.
