How memories forgotten through dementia can be reignited with scent

​

Our sense of smell is one of our most visceral instincts. It has an instant and powerful connection to memories, especially emotional memories. Researchers such as Rachel Herz have reported that odours evoke more emotionally potent memories than some other sensory cues (auditory, verbal or visual)[1]. There is some great data which evidences the unique interconnections between the olfactory area and the amygdala- hippocampus complex of our brain’s limbic system. It is this area of our brain which supports functions including emotion, behaviour, long term memory and olfaction, which underpins why the response is so powerful.

When you smell something, such as the smell of the sea, freshly cut grass, your mum’s cooking or your dad’s aftershave, you can probably pull out a range of memories and with them a range of feelings and images of these past associations. These smells connect us with the world around us and also with our past. The importance of our sense of smell has been vividly illustrated for so many people who suffered with smell loss during infection with the Covid virus, some suffering with a feeling of being isolated as a result.

It is estimated that there are approximately 44 million people worldwide living with Alzheimer's disease or a related form of dementia. As Alzheimer’s worsens people experience greater memory loss and other cognitive difficulties. It is a problem that causes distress for the sufferers and also their carers, friends and family. So, what if we can use smells to help reignite a connection to past memories and also to the world around them?

This is something we have turned our attention to at Givaudan. As the world’s leading fragrance house, we create scents that go into everything from shampoos and prestige fine fragrances to floor cleaners or air fresheners. Ten years ago our perfumers, in consultation with therapists and rehabilitation experts in Singapore, designed smells for a memory kit. The ‘smell a memory’ kit is based on a set of over 60 odours commonly experienced during everyday life in Singapore. The team worked with a small group of patients suffering form dementia. For each patient a personalised kit of ten smells was selected based on the individual’s family history, ethnicity, age and personal stories. From this individual kit of 10 smells the patient’s carer selected five that they thought were particularly relevant or special for the person with dementia.

The care givers spent 10 to 15 minutes a day with the person with dementia and the scents. The person with dementia was encouraged to share thoughts and comments whenever the scents were presented to them. Simple prompts were given asking the patient whether the smell was familiar, if they liked it and what it reminded them of, then encouraging them to talk more. The smelling sessions were easier with some patients than others. For some the scents brought very little response but for others, memories were brought to life and stories were told that would not otherwise have been heard. For one, the smell of flowers reminded her of visits to the temple, for another the smell of fish was a memory of cooking for friends and family, and for another memories of swimming and dancing on the beach even brought her to her feet to dance.

The sessions also brought benefits for the patients’ carers because they learnt more about the patients and their lives and memories, and conversations evolved that could not otherwise have been imagined.

[1] Herz, R. (2004) A naturalist analysis of autobiographical memories triggered by olfactory visual and auditory stimuli. Chemical Senses, 29, 317-324.

​

​

​

​