Memories can be triggered by the things we smell. The smell of gingerbread can bring back memories of childhood holiday baking with Grandma. The smell of a certain perfume can remind us of a loved one who passed away years ago.
Scientists have recently been involved with "sniffing out" the close relationship between the loss of smell and the simultaneous loss of memory associated with dementia. Could memory loss be reversed by developing a new form of smell therapy to perhaps encourage memories to resurface and improve cognition and self-identity? What is the connection between our olfactory sense and memories of the past, and why is that connection so important?
Did you know that your sense of smell is very different from the other senses? It is all in the brain!
The sense of smell is known as the olfactory sense. Olfactory memory is the recollection of smells. Olfactory memory is a seemingly simple function of the human brain, yet it plays a complex role in both conscious and subconscious memory. It is the most sophisticated of the five senses as it is located the closest to the hippocampus and amygdala, essentially forming a direct communication line to the parts of the brain responsible for learning, memories, and emotion.
The limbic system is responsible for a complex host of information processing...
All of the other senses must pass through a separate region of the brain before they are able to be processed. With the sense of smell, the olfactory cortex is linked directly to the the amygdala and hippocampus, which are key components to the limbic system. The limbic system is responsible for a complex host of information processing that impacts everything from the way we feel, to how we learn, to unconscious memories that impact the way we make daily choices, including how we feel about ourselves.
Scientists Learn the Connection between Smells and Memory
The National Institutes of Health have been studying behavioral neuroscience in regard to learning for many years. Part of this research includes the role that odors play in how the brain processes smells. They have recently found that odors play a crucial role in learning and memory in regard to events and places and are good cues for recalling emotional episodes.
In short, the things we smell stay with us. They become a part of our emotional memories and can be retrieved in the form of emotional responses. Certain smells can bring back long-term memories, memories that otherwise would have been lost to the conscious mind. This could potentially impact dementia treatment in a significant way.
The Role Memory Plays in Self-Identification
Identity loss is one of the symptoms associated with dementias such as Alzheimer's Disease. It is one of the most painful things to watch unfold as a loved one forgets things about identity and can't distinguish the identities of close relatives. What makes persons with dementia forget who they were? Researchers in Sweden may have uncovered a key piece of the dementia puzzle.
Smelling the inside of a new book, a person may be flooded with memories of the first day of kindergarten. That memory can trigger feelings of excitement and anxiety. It can lead down a memory trail of the important moments of that year and shape the way the person sees himself. The smell of a crisp, dry wine may remind a woman of her first date with her lifelong partner. It can trigger a string of memories and assorted emotions that define that relationship and her role in it. This almost autobiographical response may be beneficial in helping a dementia sufferer recall who he or she is.
Researchers have asked: What if the smell memory was gone? Would that mean the memories associated with that part of the brain would be locked away forever? Could identity loss associated with dementia be rooted in the loss of olfactory memory?
Researchers in Sweden have conducted the first of its kind, 20 year study exploring the role that olfaction impairment has on people with the gene that is a risk factor for late-onset dementia of the Alzheimer's type (the Apolipoprotein E gene). In the study, elderly people with this gene suffered from a loss of sense of smell and memory loss. Elderly people who did not have this gene had no such correlation between the losses of the two. The researchers suspect that the gene may be responsible somehow for the loss of both. If this is the case, it may be possible for new research to uncover ways to address the suppression of that gene or to develop an enzyme that counters its effects and possibly even reverses them.
Research into dementias and the sense of smell have burgeoned in the last decade or two. Hopefully, as more studies uncover potential solutions, the epidemic of dementia will one day become a thing of the past. It could be that evocative smells play a more crucial role than we know in memory and the progression of symptoms associated with dementia.
Olofsson, J. K., Josefson, M., Ekstron, I., Wilson, D., Nyberg, N., Nordin, S. et al. (2016). Long-term Episodic Memory Decline is Associated with Olfactory Deficits only in Carriers of ApoE-[?]4. Neuropsychologia, 85(May 2016): 1-9. Available at http://www.sciencedirect.com/science/article/pii/S0028393216300689. Last Visited April 18, 2016.
Sullivan, R.M., Wilson, D. A., Ravel, N., Mouly, A-M. (2015). Olfactory Memory Networks: from Emotional Learning to Social Behaviors. Frontiers in Behavioral Neuroscience, 9(36). Available at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4330889/. Last Visited April 18, 2016.
Woronczuk. J., Medwid, St., Neumann, L., Eshelman, S. Olfaction and Memory. Behavioral Neuroscience. Department of Psychology. Macalester College. Available at: http://www.macalester.edu/academics/psychology/whathap/ubnrp/smell/memory.html. Last Visited April 18, 2016.