Psychopathic tendencies appear to be associated with an impaired sense of smell, say Australian scientists who believe inefficient processing in the front part of the brain is to blame. Details of the experiments, conducted by Mehmet Mahmut and Richard Stevenson, from Macquarie University, appear in the journal Chemosensory Perception.
Past studies have shown that people with psychopathic traits have impaired functioning in the front part of the brain – the area responsible for planning, impulse control and acting in accordance with social norms. Dysfunction in the front part of the brain has also been linked to an impaired sense of smell.
Mahmut and Stevenson decided to investigate whether a poor sense of smell was linked to higher levels of psychopathic tendencies. Their investigation assessed manipulation, callousness, erratic lifestyles, and criminal tendencies among 79 non-criminal adults living in the community. They first assessed the participants’ olfactory ability and then measured the subjects’ levels of psychopathy. They also noted how much or how little subjects emphasized with other people’s feelings.
The researchers found that those individuals who scored highly on psychopathic traits were more likely to struggle to both identify smells and tell the difference between smells. These results, says Mahmut, show that the brain areas controlling olfactory processes are less efficient in individuals with psychopathic tendencies.
The researchers think the findings might form the basis for clinical tests. “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,” they note.