Mehmet Mahmut and Richard Stevenson of Macquarie University in Australia said studies showed people with psychopathic traits have impaired functioning in the front part of the brain -- the area largely responsible for functions such as planning, impulse control and acting in accordance with social norms.
Mahmut and Stevenson looked at whether a poor sense of smell was linked to higher levels of psychopathic tendencies among 79 non-criminal adults.
They assessed the participants' olfactory ability -- sense of smell -- as well as the sensitivity of their olfactory system. They also measured subjects' levels of psychopathy, looking at four measures: manipulation, callousness, erratic lifestyles and criminal tendencies. They also noted how much or how little they empathized with other people's feelings.
The study, published in the journal Chemosensory Perception, found individuals who scored highly on psychopathic traits were more likely to struggle to both identify smells and tell the difference between smells, even though they knew they were smelling something.
"Our findings provide support for the premise that deficits in the front part of the brain may be a characteristic of non-criminal psychopaths," the researchers said in a statement. "Olfactory measures represent a potentially interesting marker for psychopathic traits, because performance expectancies are unclear in odor tests and may therefore be less susceptible to attempts to fake good or bad responses."