Nuts, right?

Apparently if you are a psychopath, you can’t smell as well as the rest of us. That’s right, if you can’t distinguish the difference between the delicious aromas of coffee and a strawberry, it could be another one of many traits, such as an inability to show empathy and compassion, used to diagnose psychopathy.

Science writers at News Ltd. and Fairfax publications have been busy over the last week reporting the fishy-smellin’ findings of psychologists Mehmet Mahmut and Richard Stevenson of Macquarie University. Mahmut and Stevenson tested the olfactory faculty of non-criminal psychopaths with a packet of “Sniffin’ Sticks” pens as a source of odours, including coffee, leather and oranges.

Green areas of both images highlight the Orbital Frontal Cortex of the Frontal Lobe from lateral (above) and anterior (below) perspectives. Picture obtained using the Brain Explorer 2 software, developed by Allen Brain Atlas (human.brain-map.org/static/brainexplorer)

According to the article in Chemosensory Perception. All subjects (including controls) were graded on their number of psychopathic traits. Those with the highest “psychopathic scores” tended to have greater difficulty identifying and differentiating between odours.

So what does it all mean? Do we now only trust those who work in jobs that require a keen sense of smell?

Well, maybe. Failing a test in sense of smell is hardly going to define you as a psychopath. But people with psychopathic tendencies often evade or provide deceitful answers to interview/diagnostic questions. With this new piece of research, there is potential for police, psychologists and doctors to use a test in olfactory ability to help identify these people, albeit inconclusively.

Mahmut and Stevenson relate this correlation back to the orbito-frontal cortex, part of the prefrontal cortical region of the brain. This region is not only responsible for olfaction, but empathy, decision-making and reward/punishment learning characterized by theories of psychological conditioning. The prefrontal cortex is also a focus area for other neurological diseases such as schizophrenia and Alzheimer’s disease, with patients also noted for having an impaired sense of smell too.

So maybe this news isn’t as insane as first thought. It seems that people with psychopathic traits don’t smell as well as the rest of us. This is not to be mistaken with people that don’t smell as well as the rest of us and actually do not have psychopathic traits.

So just don’t jump to conclusions next time you or your friends can’t smell anything. It’s probably just a cold.


3 Responses to “Nuts, right?”

  1. Phuong says:

    Do you know or think there would be an evolutionary purpose for linking smell with empathy? I know some animals recognise each other through smell and I wonder if this is something we inherited from our primate ancestors?

  2. AJ Barty says:

    Thank you, Amanda. This work is fresh off the press. So fresh, in fact, the university hasn’t purchased the access rights to the latest volume of the journal. What I can tell you is, that from an anatomical and neurophysiological perspective, the findings are in line with what has been observed in other diseases, such as schizophrenia, where both the sense of smell and ability to feel empathy or register what is socially acceptable behaviour. The next step would be to study the sense of smell and anatomical and physiological integrity of the OFC in the context of psychopathy. What makes things difficult, is the fact that this group acknowledges a “scale” of psychopathy, that is some people exhibit more psychopathic traits than others, which could make finding association with psychopathy and any neurological dysfunction in the OFC tricky in smaller sample sizes.

    The fact is, the brain is stupidly complex. So in a way, we shouldn’t be surprised by any association between sensory perception and mental health…its all connected!

  3. Amanda says:

    Thanks for posting about such a novel finding!
    Human research is so not my area, but its something that I find really interesting.
    How has this study been received in the research area? Are people coming out to dispute the findings or is it something that is being accepted?