Paranoia has emerged as a 21st century fear, according to a new research.

Yes, a leading psychiatrist at King's College London has carried out the decade-long research and found that one in four people suffer irrational fears of either being threatened or in danger on a regular basis.

In fact, according to Dr Daniel Freeman, paranoia is far more common than had been suspected and is on the rise, as a result of growing inequity, social isolation and a far more competitive society.

"We seem to have entered an age of paranoia. And the indications are that things may only get worse. These days, we dare not let our children play outside; we are suspicious of strangers; security cameras are everywhere," 'The Independent' quoted Dr Freeman as saying.

But, he has developed a "virtual reality" method of diagnosing paranoia, in which participants wear headsets and respond to a simulated environment then complete a set of questionnaires.

One factor in the "era of suspiciousness" is the increasing number of people living in cities, he said.

Rates of paranoia are known to be twice as high in cities than in rural communities, said Dr Freeman.

"Social bonds are much looser in cities than in smaller, rural communities where ready-made, relatively stable support networks exist,” he added.

"Social isolation, a frequent drawback to urban life, is closely associated with paranoid thoughts. Unequal distribution of wealth played a major role in fostering paranoid feelings," Dr Freeman said.

He has made his claims in an upcoming book, 'Paranoia: the 21st Century Fear'.