Scent and Sensibility: The Link Between Smell and Memory

There you are, living your best life when — out of the blue — a scent transports you back in time. Maybe a savory aroma brings back memories of your dad’s soup. Or a floral waft reminds you of your grandmother’s perfume.

You’re not imagining things. Scents can evoke the memory of a loved one, a special event or a significant place in your life — or even an uncomfortable or painful moment.

“As humans, we navigate the world mainly using sight,” says psychiatrist Drew Cumming, MD. “But the primitive areas of our brains still have connections from when our ancestors relied on smell to survive. These connections are the basis for scent memories.”

Dr. Cumming explains the link between smell, memory and emotion, plus its medical implications.

How smells trigger memories

Your sense of smell starts when molecules in the air (odorants) bind to smell receptors in the back of your nose. Like a lock and key, each receptor is specific for one type of odorant. When the two meet, it produces electrical signals in nerve cells (neurons) that travel to your brain.

The first stop for these nerve signals is the olfactory bulb, located just above your nasal cavity. The olfactory bulb processes the signals and sends them to structures deeper in your brain, including your:

• Piriform cortex, which interprets nerve signals into what you know as a smell
• Amygdala, the emotional center of your brain

If there's a strong emotion with the smell, the amygdala signals the nearby hippocampus, where memories are formed. Nerve signals are also sent to the frontal lobes of your brain. This area also plays a role in memory, as well as higher-level thinking, learning and decision-making.

“Every moment, you’re bombarded with input from your senses,” says Dr. Cumming. “It’s impossible to form memories from all that input. Your brain decides whether to form a long-term memory based on the significance of the experience.”

Why are scent memories so powerful?

Research has shown that memories associated with smell carry more emotion than visual memories. One study exposed people to both smell and visual cues linked to a specific memory. Smell had a significantly greater effect on activity in the amygdala and the participants’ reported emotions.

This effect is likely due to how your brain processes smell versus your other senses. Nerve signals that relay information about sight, sound and touch typically go through the part of your brain called the thalamus. Think of your thalamus as a relay station that receives signals from all over and decides where those signals should go.

“Smell signals bypass the thalamus and go directly to the olfactory bulb and then quickly to the amygdala and hippocampus,” explains Dr. Cumming. “This unique wiring in your brain reflects the importance of smell throughout our evolutionary history.”

Smell — one of the oldest senses — evolved to help animals identify food, mating partners and danger. Although the human olfactory system has changed over time, it functions much the same as it does in animals. Scent memories result from brain connections that are designed to help us stay alive.

Why are scent memories often linked to childhood?

For many people, smell-induced memories recall experiences from childhood. The reason may have something to do with the rapid brain development in early life.

“In animals, the smell-processing parts of the brain are among the first to develop,” says Dr. Cumming. “That’s not exactly what happens in people, but childhood is when many brain connections are forming.”

As children grow, their brains go through pruning to reduce unnecessary connections and strengthen important ones. That process is a throwback to earlier periods when stronger memories meant greater survival.

What are the health implications of scent memories?

Most of the time, smells spur pleasant memories that connect you with your younger self. Afterward, you might feel calmer and happier. Some studies have reported health benefits of smell-induced memories, such as:

• Decreased markers of inflammation
• Improved memory recall in people with depression
• Slower, deeper breathing

“It also makes sense that you could use scent memories as a form of therapy,” notes Dr. Cumming. “There’s a strong link between smell and the emotional systems in our brain. Inducing a scent memory may be helpful if you’re feeling down or overwhelmed — although there’s no documented research on this.”

Sometimes, smells are linked to negative memories and emotions. One study reported scent triggers in people with post-traumatic stress disorder (PTSD). PTSD requires treatment from a healthcare provider — but there are also techniques you can use at home for less severe symptoms.

For example, if a scent memory causes mild symptoms, Dr. Cumming recommends trying grounding techniques. “These strategies can help bring you back to the present and calm stress and anxiety,” he says.