May 15, 2021

I, Science

The science magazine of Imperial College

Obsessive compulsive disorder (OCD) is a debilitating condition affecting millions everyday. It is estimated that, in the UK, 2% of people aged between 18 and 56 suffer from some form of obsessive compulsive behaviour. Despite this widespread occurrence, however, there is much we do not know about the condition.

Historically, OCD has been dismissed as having no physiological cause, but scientists have shown that there are underlying biological factors in the condition. Functional magnetic resonance imaging studies have shown that the ventromedial prefrontal cortex, normally responsible for goal-based decisions, is implicated in the condition. Neurologists have also suggested several other areas play a role.

But how these physiological deficits manifest themselves is only just beginning to be understood. A recent study carried out in the Department of Experimental Psychology at Cambridge University indicates that the compulsions are due to overactive habit forming mechanisms.

Clair Gillan, a lead researcher in the study, said: ‘The goal was to look at the habit hypothesis of OCD, to see if [sufferers] had a greater predisposition to habit formation than control subjects’. The researchers were able to analyse this by comparing the abilities of control and OCD participants. Each subject was trained to use a computer programme to gain points by clicking on the correct boxes of fruit that appeared on screen. The fruits that gained the participants points were then changed. The OCD patients showed they were significantly less able than the controls to change the habit they had learned. They did not achieve their goals as successfully and thus gained fewer points. One participant, ‘Mr J’ (a severe OCD sufferer), commented that when he saw the fruits it was as if his ‘hands knew what to do’ and followed the earlier training goals, not the newer goals.

There are several different techniques currently used to treat OCD. These include the drastic (such as surgery), the experimental (such as psychedelic drugs) and the psychological (such as behavioural therapy). ‘I think it’s a very important validation of cognitive behavioural therapy’ said Gillan commenting on her study. She highlighted in particular the ‘exposure and response prevention technique’, also known as Pavlovian extinction. Patients undergoing this therapy are exposed to their feared situation.

Whilst our knowledge of OCD has no doubt improved, there is still much to discover.