The olfactory experience, particularly scents that trigger nostalgic memories, holds a remarkable power to enhance our memory recall abilities. Experts assert that individuals, regardless of their mental health status, can harness the potency of familiar aromas to summon recollections and uplift their mood.
A recent study, featured in the February 13 edition of JAMA Network Open, delved into the potential of familiar scents in aiding individuals with depression. The findings suggest that these individuals may benefit from the evocation of specific memories through familiar aromas, potentially leading to an amelioration of their symptoms. This highlights the profound interplay between olfaction, memory, and emotional well-being, offering new avenues for therapeutic interventions in mental health care.
“Our key takeaway from this study is that people with depression have memories, they just have trouble accessing them. Odors could be one way to help these individuals improve their memory recall,” study senior author, Kymberly Young, PhD, said. She is a neuroscience researcher and an associate professor of psychiatry at the University of Pittsburgh Medical Center.
The research results indicate that scents are more potent than words in triggering memories of specific events. Moreover, the authors propose that incorporating smells into therapy sessions could aid individuals struggling with depression by breaking negative thought cycles and reshaping cognitive patterns.
“This is a terrific study from a strong group with a track record of excellent memory research in adults with depression,” said Daniel Dillon, PhD. He is an associate professor of psychiatry at Harvard Medical School in Boston. He also was not part of this new research. In fact, this may be the first study to make use of use olfactory cues to help trigger autobiographical memory retrieval for those suffering from major depressive disorder. Dillon said that the results are very promising. Dillon is also a leading researcher in the role of memory in depression.
The Importance of the Connection Between Depression and Memory
Dillon stated that there is substantial evidence suggesting that adults experiencing depression encounter difficulties in recalling specific memories.
“This has been associated with poor problem-solving and a longer course of depressive illness,” he said.
The kind of memories investigated in this study are explicit memories, which is what people typically mean when they refer to “memory” in the everyday sense — specifically, episodic memory, or recalling discrete events in your life, he explained.
There are a few reasons why this type of memory is crucial, Dillon stated. “We can use them to make smarter choices going forward, and we can use positive memories to regulate our emotions and repair our moods. In some cases, we can use negative memories to do the same. For example, remembering a past failure to help us try harder or stay on track better now,” he said.
Additionally, he noted that there are instances where retrieval can pose a challenge, particularly when it involves automatically recalling highly negative and intrusive memories.
Human Brain Is Wired to Connect Scent to Memory
Previous studies have demonstrated that among individuals without depression, aromas have the remarkable ability to evoke memories that are vivid and palpable in nature.
This phenomenon is thought to occur due to the involvement of the amygdala, a component of the brain often referred to as the “reptilian brain” responsible for regulating primal responses like fight or flight. The olfactory bulb transmits signals to the amygdala, engaging it in the process. Notably, the amygdala also plays a crucial role in directing attention towards significant events and facilitating memory retrieval.
Building upon this understanding, researchers set out to explore whether stimulating the amygdala could potentially enhance memory retrieval in individuals experiencing depression.
Researchers Compared the Effectiveness of Word Cues and Scent Cues for Recall
The research involved 32 individuals aged between 18 and 55 diagnosed primarily with major depressive disorder (MDD). Participants were permitted to use antidepressants provided they had maintained a stable dosage.
A set of 24 items, comprising equal parts word cues and odor cues, was administered to the participants. Regarding the odors, participants experienced various scents with their eyes shut. The range of potent familiar scents included oranges, ground coffee, shoe polish, and even Vicks VapoRub.
Participants were asked to think back to a specific memory from their life, be it good or bad, in response to each cue presented. Before they were exposed to the odor, they were instructed and presented with this example of a specific memory: “If the word ‘bold’ made you think of the fact that you tend to go to your local coffee shop every morning, that would not be a specific memory because it’s not a single event. Instead, you would want to think of a particular morning that you went to your local coffee shop.”
Scientists were taken aback by findings revealing that individuals experiencing depression exhibited stronger memory recall when prompted by odor cues compared to word cues. Those exposed to odor cues showed a higher likelihood of recollecting specific events, such as visiting a coffee shop last Friday, rather than general memories, like previous visits to coffee shops.
Memories triggered by odors tended to be notably vivid, imbuing a greater sense of immersion and reality. Intriguingly, odor cues were more effective in evoking recollections of positive events, despite participants not being explicitly instructed to recall positive memories, as noted by the researchers.
Findings May Help in Present Depression Treatments
The discovery that depressed adults show improved ability to recall specific memories when exposed to odor cues is a significant and novel finding. This indicates a potential clinical utility: odors could potentially be utilized to aid in memory retrieval or training for individuals with depression, as suggested by Dillon.
Dr. Young concurred, noting that existing treatments for depression primarily rely on word cues to enhance specific memory recall. However, this study suggests that odors might offer a more effective alternative.
“If we improve memory, we can improve problem-solving, emotion regulation, and other functional problems that depressed individuals often experience,” she said.
Why Different Such as Like Smells, Sights, Words, or Music Trigger
Dillon explained that every experience activates various brain regions, and when the experience is encoded into memory, the corresponding pattern of activation across these brain regions is also stored.
“When it comes time to retrieve that memory, a cue can be very helpful because it can re-instantiate part of the pattern of activation that was elicited in the first place,” he said. That can bring about a ripple effect where one region activates another region in the brain, and this continues until all the regions that “encoded” the memory are activated once more and you experience the memory, explained Dillon.
Present Mood and Tapping Into Everyday Scents
Given that many of the odors used in the study were smells that were available on a daily basis, could people tap into this in their day-to-day life simply by being more aware of what they’re smelling? Absolutely, said Young. “Taking time to appreciate smells and thinking of the memories they bring to mind could be a way to boost mood more generally,” she says.
Young pointed out that a potential drawback is the triggering of negative memories by certain smells, which might prove distressing for certain individuals.
Dillon says that people could “definitely” use these findings to retrieve past memories. “As the paper points out, none of the smells used here were exotic, and our memories are being cued to odors, sounds, and sights all the time,” he said.
The secret here is to be mindful, said Dillon. “Most of this retrieval is done when we’re on autopilot, but if a depressed adult (or anyone who wants to improve their memory) wanted to hone their memory retrieval ability, they could be more attentive to the cues in their environment, the memories those cues elicit, and whether or not those memories are specific,” he explained.
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