‘What if I just started shouting right now?’

Have you ever sat in a boring meeting and wondered: “What if I start yelling?” Or you’re driving down the road and you think: “What if I crash?”

These disturbing scenarios are known as “intrusive thoughts,” which most of us experience from time to time and may shrug off.

But for some, these can become overwhelming obsessions that lead to compulsive behavior.

As a child, Dr Nina Higson-Sweeney believed that unless she had only “good” thoughts on the way home from school, her family would suffer.

“If an intrusive thought had occurred to me, I would have restarted the walk from the bus stop,” he says. “I was really afraid that if I didn’t do it again and something happened, it would be my fault.”

Nina was diagnosed with obsessive compulsive disorder (OCD) at the age of 10 and now works as a psychology researcher at the University of Oxford, where she specializes in child and adolescent mental health.

Nina explains, “Obsessions are intrusive and unwanted thoughts, feelings, and sensations, where compulsions are repeated, ritualized actions performed to neutralize or alleviate the anxiety caused by the obsessions.” He tells the BBC’s Complex podcast.

It is thought that approximately 1-4% of the population lives with OCD, but The rate of 16-24 year olds in England reporting symptoms of the disease has more than tripled in a decade.

The condition is now the second most common mental health disorder among young adults, a major study from NHS England suggests.

Intrusive thoughts can be extremely distressing and often focus on issues that are completely at odds with a person’s values ​​or identity.

“You may have thoughts of harm to loved ones,” says Nina.

“Questioning a person’s sexual attractiveness may mean wondering whether you are homosexual or heterosexual. This may even be as extreme as worrying about whether you are a pedophile.”

“One really common one is intrusive thoughts about contamination and concerns about getting sick or spreading disease,” he says.

OCD most often begins in adolescence or early adolescence, but some people can be diagnosed by “masking or covering up distress for years,” he says.

Research suggests there may be a genetic component to developing OCD, as well as links to early life stressors such as bullying, bereavement, or family breakup.

Chartered psychologist Kimberley Wilson says almost everyone experiences distressing thoughts at some point.

“Research shows that: 80% of us have these thoughts” he explains.

For most people, these thoughts pass quickly.

“We might look at them and think they’re weird and put them aside,” he says.

If you can’t get the thoughts out of your mind, then you may need to seek help, he suggests.

“Thoughts associated with OCD do not go away, they become established and are never positive thoughts; they are aggressive, hostile and not easy to deal with. That’s when everything becomes all-consuming and leads to compulsions.”

Symptoms of compulsions may be mental, such as counting to a certain number, or visible, such as repeatedly checking car tires when you know they are good.

In these cases, “a professional or expert can figure out what is best for you,” says Nina.

Along with professional help, Nina says there are techniques people can use on a daily basis to reduce their distress.

One is learning to label thoughts. “Realizing that I am ‘having an unauthorized thought’ creates distance and reminds me that this is not me,” she explains.

Some people also find it helpful to visualize OCD as a separate thing.

“It might be helpful to draw what OCD looks like; there’s me, there’s OCD, and those are two different things.”

Personal care is also important. “Eating well, resting, and getting physical activity can help, because my OCD always gets worse when I’m stressed and not taking care of myself,” she says.

Today, Nina still lives with OCD but has learned how to cope with it.

“I never got over OCD, but I can deal with it. I now have mild, disturbing thoughts and have a lot of insight into how to manage it. When I’m stressed, they’re harder to ignore and can still lead to compulsions.”

• If you are affected by the issues in this story, you can find details of organizations offering advice and support to people in the UK at: BBC Action Line