Understanding habits in OCD & addiction

Trevor Robbins andMáiréadHealy explain to Julia Ravey how disorders like OCD and addiction could be down to problems with goal-directed and habit-based systems...

茱莉亚-我们的大多数一天可以由习惯。We wake up at a certain time, brush our teeth, take a shower, make tea, drive to work, check emails, scroll on social media, eat lunch, do tasks, drive home, cook dinner, watch telly, scroll some more, and then go to bed. While certain habits can be good for us, there are other behaviours which may not be as beneficial. We may be in a habit of eating too much sugar, or being physically inactive, or spending too much time online. And in the most extreme instances, habitual behaviours can be disruptive. Behaviours carried out can do real damage to our health, relationships, and life as a whole. There are certain conditions where the goal-directed and habit systems are thought to be compromised, as Trevor Robbins explains...

Trevor - People talk a lot about addiction habits, don't they: "I've got a drug habit, I've got a cannabis habit, I've got a smoking habit." In certain disorders, for example, substance abuse and addiction, obsessive compulsive disorder, compulsive eating, compulsive gambling, there's going to be some tendencies to these more automatic behaviours.

Julia - Trevor is currently trying to understand the underlying biology of obsessive compulsive disorder, or OCD.

Trevor - OCD is a very serious and disabling disorder. I'm talking about people who perform rituals for 12 or 13 hours a day and their lives are shattered. We think obsessive compulsive disorder may be a derangement of control over habits.

Julia - I wanted to learn more about how Trevor and his group are trying to understand OCD, so I paid a visit to his lab. I'm here to speak to Máiréad Healy, who's with Trevor Robbins' group, to hear how they are studying this debilitating condition.

Máiréad - Our lab is focused on looking at the brain basis of compulsive behavior, or how habits are formed in people with OCD, so we can learn more about the brain basis of compulsions.

Julia - And how do you go about studying OCD?

Máiréad - Sometimes we are using neuro-imaging techniques to give insight into what's happening at the brain level. We also use behavioural tests that will give us insight into what cognitive mechanisms are underpinning these behaviours. We combine them together so we can get an overall picture of both.

Julia - Máiréad let me demo one of these behavioural tests. The screen displayed several boxes with different patterns in them. I had to select one and got told if it was correct or incorrect. And then I had to keep selecting the correct image as the display changed. Which pattern was correct would change throughout the game without me knowing, and this would assess my ability to think flexibly, updating the target pattern as I went through.As I complete my task, here is Trevor to explain how, in conditions like addiction, the habit system may take over...

Trevor - One idea would be, for example, when a drug like cocaine or amphetamine has its initial hit. That hits this Pavlovian system, which gives a strong, positive approach tendency, but the issue is what happens chronically when you get this over and over again. Because habits are probably promoted by extended training, a rat responding for cocaine is just like a rat responding for food. And eventually, maybe that behaviour becomes habitual. But then the other thing you've got to realise is that there may be a predisposition to have a relatively weak goal-directed system to begin with, and that's been demonstrated in humans and in animals. So, you've got a double whammy - you've got this gradually strengthening habit plus loss of control, which we argue equates to compulsive drug seeking.

Julia - What happens in the brain of someone with OCD is currently less well understood than addiction, but there are thought to be some similarities in the loss of control of the goal-directed system, based partially in the area of the brain that sits right behind the eyes called the frontal lobe.

Trevor - It turns out that the frontal lobes are relatively disconnected in OCD and, of course, in similar addiction. That disconnectedness correlates with the degree of compulsive behaviours. That's pretty amazing that the same area is disconnected, and it relates to compulsion in both cases, although the actual nature of the compulsions are different. But we would argue that the habit system probably must gain prominence as a result of that overall down regulation of the directed system.

Máiréad - So, that task is part of a battery of tasks that we administer to participants and in OCD sufferers, we hypothesise that they will find this task difficult to do the role reversal because they'll be stuck in a more habitual behaviour.

Julia - After someone has done this type of task, then what would you go on to do?

Máiréad - We have another task that's one of the key tasks that we use because we get the participant to perform this in the scanner, so that we can relate their behaviour to what brain circuitries or brain areas are supporting this behaviour

Julia - Now, I was going to get my brain scanned, but sadly, because I have a brace on my teeth, I can't go in the scanner. But what Máiréad will be looking out for here is how the brain of people with OCD, and individuals without OCD, differ in their activity when playing a game like the one I just took part in. The group is also looking at differences in brain chemicals in these systems too, to try to paint a clearer picture of what is going on in OCD and other habitual disorders.

Mairead - We really hope that we can make an impact into the lives of people who have OCD and better our understanding of habits. We all have to get the balance right between our goal-directed systems and our habit-based systems, so this work is really important for the clinical applications, but also just to have a better understanding of how we form habits and how we can improve our daily lives by adapting to our environment in a way that will help us achieve our goals.