You’re cooking on the stove when a sudden thought comes in: you should put your hand in the hot flame. As soon as the thought comes, it disappears.

What you just experienced is an intrusive thought.

“Intrusive thoughts are any thoughts that are recurrent or uncontrollable,” says David Dozois, a psychology professor at Western University. “They could be ideas, thoughts, images or even impulses that they find disturbing and/or anxiety-provoking.”

Intrusive thoughts may be violent, disturbing or even sexual in nature. When one of these thoughts forces its way into your mind, you may feel ashamed or shocked by it and you’re not alone: according to a study from Concordia University, over 94 per cent of people experience some form of intrusive thoughts.

Scientists often look to the biopsychosocial model to explain the cause of these thoughts. The major model is an interdisciplinary look at the interactions between biological and psychological causes and how the environment affects our health.

“There are parts of the brain that are a bit disrupted, like the frontal cortex, in terms of brain function and we know that serotonin can reduce the intrusive thoughts,” Dozois says. “But the problem is it’s a bit backwards — it doesn’t mean that low serotonin is the cause [of intrusive thoughts]. There are multiple causes and there are behavioural conditions as well.”

Often, when people have intrusive thoughts, they’ll try to neutralize them by doing something within their control — for example, someone who experiences germaphobia may feel inclined to continuously wash their hands.

“The problem, of course, is those types of things are only helpful in the short term. You never deal with the fear structure or what’s going on behind that,” says Dozois. 

When people try to suppress intrusive thoughts, it may only get worse, which can become harmful to a person’s quality of life. 

“We think there’s more power to thought than there really is,” Dozois explains. “The reason [people] want to neutralize is because there’s a notion of ‘thought-action fusion.’”

Thought-action fusion is when you believe that thinking about an action is the equivalent to acting it out. For example, if the random thought to harm your sibling came to mind, you would think the intrusive thought is as bad as the action itself. 

So instead, we try to pretend we don’t have these thoughts at all. Unbeknownst to the average person, this only makes things worse.  

“We’re not good at suppressing thoughts — it rebounds and makes it more present, because how would you know if you’ve gotten rid of a thought if you haven’t checked if it’s still there?” says Dozois.

So the best way to deal with intrusive thoughts is to accept them.

“If I pulled the fire alarm in the building, it’s going to be just as loud whether there’s a real threat or not,” Dozois says. “It’s the same with our bodies — if our brain says ‘there’s a threat,’ the alarm system’s going to go off strongly whether that threat is real or not. Part of what we need to do is face our fears.”

Dozois also adds that cognitive behavioural therapy and medication like selective serotonin reuptake inhibitors can also help suppress these thoughts but intrusive thoughts will never fully go away. 

“Those thoughts will come and go, and they'll always be around,” explains Dozois. “When you accept it, it tends to harm you much less and treat it like brain noise. It doesn’t mean anything. The faster you accept it, the quicker it goes away.”

A complete list of mental health resources at Western can be found here.


Sarah is a Culture Editor for volume 114. Email her at or find her on Twitter @sarahkwallace7

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