Smells become emotionally charged in cognitive decline because the olfactory system—the part of the brain responsible for processing smells—has a unique and direct connection to the brain’s memory and emotion centers, specifically the hippocampus and amygdala. These brain regions are crucial for forming and retrieving memories and for processing emotions. In conditions like Alzheimer’s disease and other neurodegenerative disorders, these areas are among the first to be affected, which changes how smells are perceived and emotionally experienced.
The sense of smell is different from other senses because it bypasses many brain regions and connects straight to the limbic system, which governs emotions and memory. This direct pathway means that smells can trigger vivid, emotional memories more powerfully than sights or sounds. For people experiencing cognitive decline, such as dementia, this connection remains relatively preserved even when other cognitive functions deteriorate. As a result, certain scents can evoke strong emotional responses and memories that might otherwise be difficult to access. For example, the smell of freshly cut grass or lavender can bring back feelings of comfort, calm, or nostalgia, sometimes transporting a person back to moments from their past in a way that feels immediate and real.
In cognitive decline, the loss or alteration of the sense of smell often appears early and can worsen as the disease progresses. This olfactory dysfunction is linked not only to memory loss but also to emotional changes such as increased anxiety or depression. When the ability to smell diminishes, people lose a source of pleasure and emotional connection—like enjoying the aroma of food or the scent of a loved one’s perfume—which can lead to social withdrawal and emotional distress. Moreover, changes in olfactory input affect how the brain processes emotions, potentially reducing the emotional salience of experiences and contributing to mood disorders.
Interestingly, olfactory stimulation—exposing individuals to varied and novel scents—has shown promise in improving cognitive function and emotional well-being in those with cognitive decline. Engaging the sense of smell with different aromas can activate the brain’s memory and emotion centers, potentially enhancing memory retention, reducing anxiety, and improving sleep quality. For example, lavender is known for its calming effects and ability to improve sleep by acting on the hippocampus. Regular exposure to changing scents has been found to significantly boost memory performance in older adults, suggesting that smell training might be neuroprotective and help slow cognitive decline.
The emotional charge of smells in cognitive decline also relates to how the brain’s olfactory bulb and related structures interact with inflammation and brain chemistry. In some cases, inflammation linked to respiratory or neurodegenerative diseases can affect the amygdala, altering emotional regulation and making smells more or less emotionally intense. This complex interplay means that smells can sometimes trigger strong emotional reactions, both positive and negative, depending on the individual’s brain state and disease progression.
In practical terms, this means that scent-based therapies and olfactory training are becoming important tools in dementia care. By carefully selecting and varying scents, caregivers can help unlock emotional memories, reduce agitation, and improve quality of life for people with cognitive decline. The emotional power of smell offers a unique window into the brain’s preserved pathways, allowing moments of recognition, comfort, and connection even as other cognitive abilities fade. This makes the sense of smell a vital and often underappreciated aspect of understanding and supporting those living with neurocognitive disorders.
