You may be one of the millions of people who smell the scent of evergreen and think of Christmas trees. Or the smell of a certain meal cooking in the kitchen can take you back to your childhood. This connection between your sense of smell and the memory centers in your brain is remarkable, and scientifically proven. More on that in a minute.
In recent years researchers have wondered if harnessing specific smells could help to increase your mental focus, clarity, and memory recall. This is especially important for people who are older or suffering from memory loss or even anxiety and depression. People diagnosed with clinical depression have real difficulty recalling specific events in their lives. They can remember general events (in a negative light) like regular visits to a café, but don’t remember having an enjoyable time with friends at the same café yesterday morning.
Memory Loss in Mood Disorders
An aspect of major depressive disorder (MDD) is a bias towards broad, overgeneralized negative memories such as “I am a failure” or “I fight with my friends a lot,” rather than specific times when they were successful, or when they had fun with their friends.
Interestingly, even when depressive symptoms are in remission, this inability to recall specific (autobiographical) memories persists, which suggests this type of forgetfulness is a trait of the disorder with a potentially causal role in its development.
To help unlock specific memories in patients, psychologists use trigger words or visual prompts. Certain word cues can bring back a specific memory, allowing them to escape negative thoughts, rewire thought patterns, and set off on the road to healing. But what about smells?
In the first study of its kind, researchers found that smelling certain scents was more effective than any word cue.
Specific Scents Elevate Mood and Memory
Dr. Kymberly Young at the University of Pittsburgh theorized that using scents would be a better approach to jogging autobiographical memories. She had several good reasons to believe this.
Odor has been linked with cognition, mood, and memory in many studies of healthy adults. For example, rosemary has been shown to elevate mood, enhance aspects of cognition, and improve long-term memory. Peppermint improved performance on demanding cognitive tasks and reduced mental fatigue. Citrus has relaxing, calming, and mood-uplifting effects. Extracts of sage improve cognitive performance and mood.
And it’s only the beginning...
The science shows that losing your sense of smell is linked to depression. What’s more, people with depression are more likely to have a reduced sense of smell, and the more the sense of smell diminishes, the worse symptoms of depression become.
A systematic review of a dozen randomized controlled trials published in 2017 found aromatherapy was “an effective therapeutic option for the relief of depressive symptoms in a wide variety of subjects.”
Odors Are a Direct Route to the Amygdala
As we mentioned earlier, scents trigger memories that feel vivid and “real” in healthy individuals. The likely reason for this is because they directly engage the brain’s limbic system, especially the amygdala, through nerve connections from the olfactory bulb.
Although the amygdala controls emotional responses and mood, it also directs attention and focus to important events that help with memory recall. Unlike sound and vision, odors directly communicate with the amygdala while the other senses get there via a circuitous route. That’s why scents can trigger strong, often emotional, memories in a way that other stimuli may not.
So, Dr. Young had every reason to believe her theory was correct. But would her study be able to show it?
Odors are More Vivid
Volunteers for this study included 26 women and six men aged 18 to 55 years with major depressive disorder. The researchers presented them with 24 items, including odor or spoken word cues, and then asked them to recall a specific memory – good or bad - from their life in response to each cue.
The scents included tomato ketchup, ground coffee, vanilla extract, wax shoe polish, and Vicks VapoRub.
The findings showed a whopping 68.4 percent of participants recalled more specific autobiographical memories for odor cues compared to 52.1 percent for word cues. In addition, odor-cued recall was rated “more arousing and vivid” compared to word cues, and the volunteers were more likely to remember positive events.
Dr. Young explained the results, saying, “It was surprising to me that nobody thought to look at memory recall in depressed individuals using scent cues before. If we improve memory, we can improve problem-solving, emotion regulation, and other functional problems that depressed individuals often experience.”
Dr. Young intends to extend this research by using a brain scanner to show how scents engage the amygdala of people with major depressive disorder and do so more effectively than word cues.
Our Takeaway
While this is the first scientific trial involving scent cues in people suffering from depression, there’s a wealth of research showing how scents can improve cognitive function. So, whether you’re battling depression or not, try some of the scents proven to help, such as: rosemary for long-term memory, peppermint to increase focus, sage for overall cognitive function, and citrus to relax and calm an anxious mind.
The easiest way to enjoy aromatherapy and its brain-boosting benefits is to use a diffuser and high-quality essential oils.
Best Regards,
The Green Valley Team
- Sánchez-Vidaña DI, et al. Evid Based Complement Alternat Med. 2017:5869315. The Effectiveness of Aromatherapy for Depressive Symptoms: A Systematic Review
- Leiker EK, et al. JAMA Netw Open. 2024 Feb 5;7(2):e2355958. Recall of Autobiographical Memories Following Odor vs Verbal Cues Among Adults With Major Depressive Disorder
- UPMC News 2/13/2024 Are You Depressed? Scents Might Help, New Study Says
