Psychopaths have a remarkably poor sense of smell, according to a new study.

Researchers in Australia tested a theory that psychopathy - a severe personality disorder characterised by lack of empathy, antisocial behaviour and callousness - may be linked to impaired smell ability.

Both phenomena have been independently traced to dysfunction in part of the brain called the orbito-frontal complex (OFC).

Mehmet Mahmut and Richard Stevenson of the Department of Psychology at Sydney's Macquarie University trialled the olfactory skills of 79 individuals, aged 19 to 21, who had been diagnosed as non-criminal psychopaths and lived in the community.

Using "Sniffin' Sticks" - 16 pens that contain different scents, such as orange, coffee and leather - they found the participants had problems in correctly identifying the smell, and then discriminating it against a different odour.