What is smell therapy for dementia?

There’s something about the scent of freshly baked bread, the smell of your mother’s perfume or the earthy aroma of rain on dry soil. These scents don’t just fill the air – they take us back to specific moments in time, to memories we didn’t even know we were holding onto.    

For many, these smells serve as gentle triggers, reconnecting us with people, places and feelings long past. Now imagine if this power could be harnessed as therapy.    

That’s the premise of smell therapy for dementia, an exciting and emerging area of research.    

While there’s currently no known cure for dementia – a condition that impacts memory, thinking, mood and behaviour – prevention and symptom management are key research areas. Therapies like smell-based interventions, which are being researched in the Mind Your Nose Study, show the potential for psychological or cognitive treatments to help slow down or even prevent the development of dementia. 

New ‘smell therapy for dementia’ research proves promising    

For more than 15 years, Associate Professor Alex Bahar-Fuchs – a clinical neuropsychologist in Deakin’s SEED Lifespan – and his colleagues have studied memory training and other thinking skills through vision and hearing.   

But it wasn’t until recently that they’ve become increasingly interested in training memory through the sense of smell.    

 In the Mind Your Nose Study, funded by the Alzheimer’s Association, Assoc. Prof. Bahar-Fuchs and his colleagues developed game-like tasks designed to train memory. In one version of the task, participants were required to remember the locations of pairs of smells. In the other version, they were asked to remember the location of pairs of visual stimuli.   

The challenge? Participants needed to recall the location of these paired stimuli and remove them from the board in as few steps as possible. Picture something like the childhood card game ‘Memory’, but with sensory objects.   

‘We were very interested in seeing whether people can not only improve on their memory for smells, but also whether that improvement will generalise to memory beyond the sense of smell,’ says Assoc. Prof. Bahar-Fuchs.   

What’s the link between scent and dementia?    

Researchers have long known about the close link between the sense of smell, the loss of sense of smell and the development of cognitive decline in dementia.   

 ‘We understand that there are very close links between the parts of the brain where smells are processed and parts of the brain that are affected in many of the neurodegenerative diseases that lead to dementia,’ says Assoc. Prof. Bahar-Fuchs.   

Alzheimer’s disease, which is the most well-known cause of dementia, causes changes in the brain in areas that are critical for not only memory and thinking, but also for the processing of smells.   

‘We now know that people who lose their sense of smell in the context of ageing are at higher risk of developing dementia,’ explains Assoc. Prof. Bahar-Fuchs.   

This is why new groundbreaking research in smell therapy for dementia has made such significant waves.  

Smell therapy for dementia: unpacking the latest research on dementia treatments    

Interestingly, research has shown that the sense of smell is highly trainable. ‘It means that people who are exposed systematically to odours can actually show significant improvements in their ability to detect and identify smells,’ says Assoc. Prof. Bahar-Fuchs. ‘This may hold true particularly when exposure is intentional and mindful rather than passive.’  

He adds that this improvement in discriminating, identifying and recalling smells can play an important role in improving cognitive function, such as thinking and memory skills.    

What happens to your sense of smell with dementia?    

The sense of smell begins in the brain when it detects an odour. ‘This starts through perceptual processing, and characterising some qualities of the smell, its intensity, its pleasantness and whether it’s the same or different from some other smell,’ explains Assoc. Prof. Bahar-Fuchs.   

From there, the brain then moves on to more complex processing of the information. This includes identifying and being able to name the smell, making some associations of what it is related to and determining if the scent is familiar or new.   

In Alzheimer’s disease and other neurodegenerative conditions, damage in the brain impacts these levels of processing, which results in a gradual loss of these abilities.   

‘In the early stages of Alzheimer’s disease, for example, people are still typically able to detect the presence of a smell but are less likely to be able to differentiate it from other smells – and even less likely to call it by its name, identify some of its general properties and so on,’ says Assoc. Prof. Bahar-Fuchs.   

The more complex processes are impacted first, and as the individual’s condition worsens, other abilities are gradually lost. This is where smell therapy for dementia comes in.   

Why scents are being used to treat cognitive decline and depression     

The good news? Research into dementia and smell sensitivity shows groundbreaking promise for treatment.    

The Mind Your Nose Study showed that when older participants with subjective cognitive concerns underwent smell therapy, they didn’t just get better at remembering scents – they also showed improvement when they were assessed on visual memory tests.    

This is noteworthy because, while it’s long been demonstrated that people who train on visual memory tasks improve on visual memory tasks, they didn’t improve on a measure of olfactory (smell) memory.   

‘That shows an interesting dissociation where people can improve their memory for smells and simultaneously that improvement generalises to another type of memory,’ says Assoc. Prof. Bahar-Fuchs. ‘We believe that the sense of smell is more potent, more flexible in bringing about this type of generalisation than training memory through the sense of through vision or auditory. So that’s a very exciting finding.’     

What other current research on dementia is making waves?    

Dementia research has exploded in the last couple of decades. Assoc. Prof. Bahar-Fuchs attributes this to significant strides made in understanding the disease – from the changes in the brain and genetics to early diagnostic markers and the development of both pharmacological and non-pharmacological interventions.   

There has been a lot of discussion in the media about a new drug treatment for Alzheimer’s disease that reduces the accumulation of amyloid, which is a protein in the brain and implicated in the onset of Alzheimer’s disease. Two new anti-amyloid drugs (donanemab and lecanemab) have recently been approved in the US by the Food and Drug Administration (FDA) but rejected by the Australian TGA, leading to disappointment among some key researchers in Australia.   

This is yet another reason why developments in non-pharmacological interventions – like Deakin’s research into smell therapy for those at risk of dementia – are so significant.    

A final word on smell therapy for dementia     

In many ways, research into smell therapy for those at risk of dementia is still in its infancy. ‘In the field of non-pharmacological interventions and olfactory based interventions, we are still learning a lot about how to design these interventions in a way that maximises their relevance for individual people,’ says Assoc. Prof. Bahar-Fuchs.   

He believes that there is always something that can be done to improve the quality of life of people with or at risk of dementia. The development of smell therapy for those at risk of dementia is just one example.  

People will now live with dementia for more than a decade, 15 years, 20 years,’ he says.   

It’s absolutely critical that we leave a legacy through which they are included as part of society, that they are seen as valuable members of society, even with a chronic condition like dementia.’