Aromatherapy May Improve Cognition in Older Adults

Study shows "olfactory enriched" scent group displayed a 226% increase in cognitive performance, measured through standardized word recall tests

Recent research from the University of California, Irvine, shows that aromatherapy may significantly enhance cognitive function in older adults. This study exposed participants aged 60 to 85, who did not have memory impairment, to specific scents for two hours nightly over a six-month period using a diffuser. Compared to a control group, individuals in the "olfactory enriched" scent group displayed a 226% increase in cognitive performance, measured through standardized word recall tests. Brain imaging also suggested improved structural integrity in pathways critical to memory and decision-making.

This approach highlights how olfactory stimulation can reinforce memory pathways, with potential implications for combating age-related cognitive decline and dementia. The study leverages the known link between smell and memory, suggesting that targeted aromatherapy could serve as an accessible, non-invasive cognitive enhancer​.

Olfactory loss precedes or accompanies cognitive decline in dementia

The olfactory system is the only sensory system that has direct projections to the limbic system which is crucial for memory and emotion, and which is the most relevant for this investigation, while the other sensory systems have indirect connections to this region via the thalamus. This unique access to the brain’s learning and memory systems may allow the olfactory system to prevent or reverse the deterioration of these systems via direct neural activation.

As people age, the deterioration of their olfactory ability occurs before the deterioration of their cognitive abilities. Additionally, olfactory loss results in a significant loss of both gray matter and white matter in human brains. Olfactory loss predicts the loss of gray matter in the hippocampus of older adults and continuing loss of olfaction predicts the further loss of hippocampal gray matter as they first develop Mild Cognitive Impairment (MCI) and then Alzheimer’s disease (Franks et al., 2015; Chen et al., 2021).

Haehner et al. (2013) showed that patients with Parkinson’s disease improved their verbal fluency after olfactory enrichment. Birte-Antina et al. (2018) provided olfactory enrichment for adults with 4 essential-oil odorants twice a day for 5 months. Controls solved daily Sudoku puzzles during that time. The olfactory-enriched group had a significant improvement of olfactory function, improved verbal function, and decreased depression symptoms.

Increased complexity of olfactory enrichment remarkably improves dementia. Cha et al. (2022) exposed older adults with moderate dementia either to 40 odorants twice a day for 15 days or to no olfactory enrichment. The olfactory-enriched group showed highly significant improvements in memory, olfactory identification, depression symptoms, attention, verbal fluidity, and language skills relative to controls.

The study shows that minimal olfactory enrichment at night using an odorant diffuser results in significant improvements in both verbal memory and the integrity of a specific brain pathway. Our findings should stimulate larger scale clinical trials systematically testing the therapeutic efficacy of olfactory enrichment in treating memory loss in older adults.