The secret to making other people laugh could be darker than you think. A new study has found that comedians have an unusual personality structure, displaying high levels of psychotic personality traits.

Recent studies have looked at the common belief that creativity is linked with madness. However, these studies have tended to focus on people working in the arts, rather than in comedy. UK researchers decided to look into this further.

They looked at 523 comedians - 404 men and 119 women - who were mainly from the UK, the US and Australia. All were recruited from comedy clubs, associations, societies and agencies.

These were compared with 364 actors and 831 people who did not have creative jobs.

All of the participants carried out an online questionnaire, which aimed to measure psychotic traits in healthy people. The questionnaire looked specifically at four areas:
-Unusual experiences, such as a belief in paranormal activities
-Cognitive disorganisation, which includes a difficulty in focusing thoughts
-Introvertive anhedonia, which refers to a reduced ability to feel social and physical pleasure. This can include avoiding intimacy
-Impulsive non-conformity, which relates to impulsive or antisocial behaviour.

The study found that comedians scored much higher on all four types of psychotic traits compared to people working in non-creative jobs.

The actors also scored higher than the non-creative group, but in three of the traits and not to the same extent as the comedians.

"The creative elements needed to produce humour are strikingly similar to those characterising the cognitive style of people with psychosis - both schizophrenia and bipolar disorder. Although schizophrenic psychosis itself can be detrimental to humour, in its lesser form it can increase people's ability to associate odd or unusual things or to think ‘outside the box'.

"Equally, manic thinking, which is common in people with bipolar disorder, may help people combine ideas to form new, original and humorous connections," suggested Prof Gordon Claridge of the University of Oxford.

Details of these findings are published in the British Journal of Psychiatry.