One in three people in the UK regularly suffers paranoid or suspicious fears, clinical psychologists have found.
Worry is often unnecessary
A team at the Institute of Psychiatry at King's College London interviewed 1,200 people about whether they had thoughts about others doing them harm.
They found levels of paranoia were much higher than previously suspected - and almost as high as those for depression and anxiety.
The researchers say paranoia can cause real distress.
The study found that:
- Over 40% of people regularly worry that negative comments are being made about them
- 27% think that people deliberately try to irritate them
- 20% worry about being observed or followed
- 10% think that someone has it in for them
- 5% worry that there is a conspiracy to harm them
Researcher Dr Daniel Freeman said: "We were astonished at how common paranoia and suspicion are amongst the population.
Greg, 19, student: "If I'm with a friend and someone rings them on their mobile and they tell the caller they're with me, well if the caller then says something I can't hear and the friend I'm with laughs, I always think that the person on the other end of the phone said something horrible about me."
"Understandably there are certain instances when it is important to practice caution, such as taking money from a cash machine without alerting too much attention and walking down a poorly-lit street at night.
"Following last year's London bombings, it is natural that underground train travellers are more vigilant than before.
"However, our research demonstrates that there can be a tendency to exaggerate our fears."
"Our study shows just how many of us are worrying - probably unnecessarily - about something that might not happen instead of getting on with the more enjoyable and productive parts of our lives.
"We also found in our study that these suspicious thoughts can cause real distress."
Dr Freeman said in the past paranoid thinking had been assumed to occur only in people with severe mental illness, partly because of a reticence in the general population about talking about paranoid thoughts.
WAYS TO OVERCOME PARANOIA
Remember paranoid thoughts are common
Share thoughts with trusted others
Imagine another person's perspective
Do not treat thoughts as facts and think of alternative explanations for events
Try not to ruminate on the thoughts
Do not let the thoughts stop you from doing what you want to do
Remember the positive things about yourself
From Overcoming Paranoid and Suspicious Thoughts, published by published by Constable and Robinson
He said that until recently little was known about how to help people overcome their fears.
But he said there were now effective ways - such as cognitive behaviour therapy and self-help techniques - to tackle the problem.
Dr David Harper, a senior lecturer in clinical psychology at the University of East London, agreed that paranoid thoughts were probably more common than people realised.
He said: "People need to realise that these sorts of thoughts are not that rare, and should not be too frightened by them."
Dr Harper said there was probably something about contemporary Western society which encouraged feelings of paranoia.
"There are surveys to show that people are much less willing to trust others than they once were," he said.
He suggested the media had helped create a climate of suspicion by playing on people's fears.
A new website - paranoidthoughts.com - is being launched to provide information on paranoid thoughts, advice on seeking help, and opportunities for people to share their experiences.