News release

From: University of Technology Sydney (UTS)

A long-held view is that compulsive behaviours involve individuals getting stuck in a “habit loop” that overrides self-control, however new research in rats from the University of Technology Sydney (UTS) suggests this might not be the case.

Compulsive behaviours are common across many mental health conditions, including obsessive-compulsive disorder, substance and gambling disorders, where people repeat actions despite negative consequences. These conditions affect millions worldwide.

Senior author, behavioural neuroscientist Dr Laura Bradfield, said ordinarily habits are useful because they allow us to act on autopilot, such as when we brush our teeth or drive a familiar route, so we can think about other things.

“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 behaviour,” said Dr Bradfield.

“With compulsive behaviours such as handwashing or playing the pokies, the scientific view has been that these behaviours have become entrenched habits, so it is difficult for people to break free and take back 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 behaviour.”

The study, led by Dr Arvie Abiero as part of his PhD research at UTS, and recently published in Neuropsychopharmacology, tracked how rats learn and control their actions and found that triggering inflammation in the striatum shifted behaviour toward more deliberate, effortful decision-making rather than habit.

“Surprisingly, the animals became more goal-directed and continued to adjust their behaviour based on outcomes, even in situations where habits would normally take over,” said Dr Bradfield.

The research team traced this effect to astrocytes – star-shaped cells in the brain that support neurons. Inflammation caused these cells to multiply and interfere with nearby groups of neurons that control movement and decision-making.

The research will be of interest to psychologists, psychiatrists, patients and caregivers working with compulsive disorders. The findings suggest that, in some cases, compulsive behaviour may come from too much (albeit inappropriate) deliberate control rather than too little.

The study suggests that drugs that target astrocytes and reduce neuroinflammation, as well as broader anti-inflammatory measures such as exercise or getting better sleep, could offer new avenues for treatment.

“There’s a lot of compulsive behaviour 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 behaviours, 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.