Greetings Earthlings! 🙂

As I mentioned in last weeks post on taste sensitivity, this week we’re going to discuss sensitivity to smell in autism.

As with other senses we have discussed, autists can be either hyposensitive or hypersensitive to odours. One autist may enter a malodorous environment without noticing anything amiss, another autist may wretch, or worse!

As a child, my nose was particularly sensitive to my environment (although judging by how I could taste the beer my friends were drinking yesterday evening from the fumes alone, this may still be the case on occasion 😛 ). Bad smells were especially trying- the smell of salads, fish, cigarette smoke, incense, even something so simple as a bag of popcorn could easily turn my stomach.

But it wasn’t all bad- this sensitivity comes with a heightened appreciation for pleasant smells too 🙂

Baking, chocolate, nice perfumes, the outdoors, the smell of metal (don’t ask me why I love this one so much- must be something to do with my taste in music! 😛 😉 )- in fact, such smells are not only a sensory sensation, but can also be used to help calm an autist.

As easily as an unpleasant smell could unsettle me, the right smell could calm me back down again as a child.  I always kept a teddy or a blanket near at hand that I could smell to help soothe and calm me and to lull me off to sleep- I couldn’t sleep without one particular teddy until I was 16!

^^^^My teddy was a lot more raggedy than this…😬

So why does smell affect autists so much?

Interestingly, some studies indicate that there are no differences in sensitivity to smell between autists and their neurotypical peers, however, much research points to the cortex of the brain. This region is heavily involved in smell processing, and yep, you guessed it- the autistic brain shows signs of dysfunction in this region. In fact, the pre-frontal cortex shows signs of overgrowth and excessive linkage in the neurons (just like an overloaded plug), so no wonder sensory perception is altered in autists! This region is also associated with the formation and retrieval of long term memories, which could also explain why smells are often tied to memory recall in autists (which I will explore in more detail at a later stage 🙂 ).

One study also shows that autists may not inhale smells in the same way to their neurotypical peers. Evidence suggests that autists inhale deeply and intensely for both pleasant and unpleasant smells, whereas neurotypicals will tentatively sniff in the presence of an offending odour, which could further explain differences in scent processing.

In addition to this, research suggests that alterations in smell can influence social behaviours. A recent study in fact suggest that autists cannot smell fear and that there is a reversal in their response to fear. In this study, a group of autists were calm when presented with a sample of sweat from a skydiver, whereas their neurotypical peers exhibited classic signs of fear. In contrast, their fear levels increased when presented with the sweat sample from a calm individual!

In other words, an autists social behaviour may be affected by an inability to interpret social cues carried in odours- the mind boggles!

So there we have it dear Earthlings- hope this post didn’t ‘stink’ too badly 😛 😉

Enjoy the weekend everyone! 🙂

Aoife