Research
I’ve compiled some key research that supports the Aromatics Therapy modality
Smell Recovery
These studies collectively highlight the potential of olfactory training, including the use of essential oils and patient-preferred scents, in improving olfactory function and inducing beneficial neural changes in individuals with olfactory disorders.
Olfactory Training with Essential Oils for Patients with Post-COVID-19 Smell Dysfunction: A Case Series
(Published: 2023)
This case series explored the impact of a 30-day olfactory training protocol using plant-derived essential oils on patients experiencing prolonged post-COVID-19 smell dysfunction. Participants reported significant improvements in self-assessed olfactory function and quality of life, suggesting that essential oil-based OT may benefit post-viral olfactory impairments.
The Efficacy of Olfactory Training in Improving Olfactory Function: A Meta-Analysis
(Published: May 2024)
This comprehensive meta-analysis evaluated 36 studies to determine the effectiveness of olfactory training (OT) in rehabilitating olfactory function. The analysis revealed a moderate to large positive effect of OT on general olfactory function, with factors such as training duration, age, and anosmia diagnosis significantly influencing outcomes.
Improved Odor Identification Ability and Increased Regional Gray Matter Volume After Olfactory Training in Patients with Idiopathic Olfactory Loss
(Published: April 2021)
This study investigated the effects of a 12-week olfactory training program on patients with idiopathic olfactory loss. Results demonstrated significant improvements in odor identification abilities and increased gray matter volume in specific brain regions associated with olfaction, suggesting that OT can induce neuroplastic changes and enhance olfactory function.
Cognitive Health
The following studies suggest a significant link between olfactory function and cognitive health, indicating that olfactory assessments and interventions could help detect and mitigate cognitive decline.
Does Olfactory Training Improve Brain Function and Cognition? A Systematic Review
(Published: February 2023)
This systematic review examined the effects of olfactory training (OT) on brain function and cognition. The reviewed studies provided emerging evidence that OT is associated with improved global cognition, particularly in verbal fluency and verbal learning/memory. Additionally, OT was linked to increased volume of olfactory-related brain regions, including the olfactory bulb and hippocampus, and altered functional connectivity.
Characterizing the olfaction and dementia association in the community
(Published: March 2025)
This study provides evidence that olfactory impairment, a common sensory deficit in older adults, is among the earliest signs of Alzheimer’s disease and several other neurodegenerative diseases. The research suggests that poor olfaction is associated with Alzheimer’s disease dementia due to pathology in brain regions involved in central olfactory processing.
[Study not yet available online as of April 2025.]
Overnight olfactory enrichment using an odorant diffuser improves cognition in healthy older adults
(Published: September 2023)
This study explored olfactory enrichment at night to improve cognitive ability in healthy older adults. The results indicated that overnight exposure to various odors led to significant improvements in cognitive performance, suggesting a potential non-invasive method to enhance brain function in the aging population.
The role of olfactory dysfunction in mild cognitive impairment and Alzheimer's disease: A comprehensive meta-analysis
(Published: August 2024)
This comprehensive meta-analysis investigated the association between olfactory deficits in individuals with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). The findings highlighted that olfactory dysfunction is significantly associated with both MCI and AD, underscoring its potential as a biomarker for early diagnosis.
The role of olfactory dysfunction in mild cognitive impairment and Alzheimer's disease: A comprehensive meta-analysis
(Published: August 2024)
This comprehensive meta-analysis investigated the association between olfactory deficits in individuals with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). The findings highlighted that olfactory dysfunction is significantly associated with both MCI and AD, underscoring its potential as a biomarker for early diagnosis.
Memory
These studies highlight the significant relationship between olfactory stimulation and memory enhancement, suggesting potential therapeutic applications for olfactory training in improving cognitive health
Long-Term Olfactory Enrichment Enhances Cognitive Flexibility in Mice
(2024)
This animal study examined the impact of prolonged olfactory enrichment on cognitive abilities in aging mice. Results indicated that mice exposed to diverse odors over their lifespan exhibited improved spatial memory and cognitive flexibility. These cognitive enhancements were associated with increased noradrenergic innervation in the hippocampus, suggesting a link between olfactory stimulation and memory-related brain plasticity.
- Study [Needs Link]
Olfactory Training Increases Hippocampal Thickness in Mild Cognitive Impairment Patients
(2022)
This randomized controlled trial assessed the effects of olfactory training on brain morphology in patients with mild cognitive impairment (MCI). After four months of twice-daily exposure to various odors, participants demonstrated increased cortical thickness in the hippocampus, a region crucial for memory. These structural changes correlated with improvements in both olfactory and cognitive functions, suggesting that olfactory training may help prevent hippocampal atrophy in MCI patients.
- Study [Needs Link]
Systematic Review: Olfactory Training's Impact on Brain Function and Cognition
(2023)
This systematic review analyzed multiple studies to determine the effects of olfactory training on brain function and cognition. The findings suggest that olfactory training is associated with improvements in global cognition, particularly in verbal fluency and memory. Additionally, structural changes were observed in olfactory-related brain regions, including the olfactory bulb and hippocampus, indicating that olfactory training can induce neuroplasticity and enhance cognitive performance.
- Study [Needs Link]
Reducing Anxiety
These studies collectively suggest that certain essential oils, particularly Citrus aurantium, lavender, and copaiba, may have beneficial effects in reducing anxiety levels.
Essential Oils for Treating Anxiety: A Systematic Review of Randomized Controlled Trials and Network Meta-Analysis
(2023)
This comprehensive review analyzed 44 randomized controlled trials involving 3,419 participants to evaluate the efficacy of various essential oils in reducing anxiety. The study found that essential oils, particularly Citrus aurantium (bitter orange), significantly decreased both state and trait anxiety levels. The authors concluded that Citrus aurantium essential oil is highly recommended for treating anxiety due to its notable effectiveness.
Benefit of Inhalation Aromatherapy as a Complementary Treatment for Stress and Anxiety in a Clinical Setting – A Systematic Review
(2023)
This systematic review examined 76 randomized controlled trials and clinical studies conducted between 2000 and 2021, involving a total of 6,539 patients. The review found that over 70% of the studies reported a positive effect of inhalation aromatherapy, particularly with lavender, rose, and orange oils, on reducing stress and anxiety levels in clinical settings.
Anxiety-Reducing Effects of Lavender Essential Oil Inhalation: A Systematic Review
(2023)
This systematic review focused on the anxiolytic effects of inhaling lavender essential oil. The analysis, which included studies published between 2018 and 2022, found that lavender oil inhalation significantly reduced anxiety levels in various populations. The authors highlighted lavender’s potential as a non-invasive intervention for anxiety relief.
The Effect of Copaiba Oil Odor on Anxiety Relief in Adults under Mental Workload: A Randomized Controlled Trial
(2022)
This randomized controlled trial evaluated the impact of inhaling copaiba oil on anxiety relief in adults subjected to mental stress tasks. The study found that participants who inhaled copaiba oil exhibited significantly lower state anxiety scores, heart rates, and salivary cortisol levels compared to the control group, suggesting that copaiba oil may effectively alleviate anxiety under mental workload conditions.
Attention & Cognition
These studies suggest that certain essential oils may have beneficial effects on attention and cognitive performance.
This study investigated the impact of lavender essential oil inhalation on cognitive flexibility in healthy adults. Participants performed a task-switching paradigm before and after inhaling lavender essential oil. The results demonstrated significant improvements in reaction time and response accuracy following inhalation. Electroencephalogram (EEG) analyses revealed increased theta and alpha power in the prefrontal and frontal regions, indicating enhanced relaxation and cognitive processing. These findings suggest that lavender essential oil inhalation can facilitate attentional shifting and improve cognitive performance. Lippincott Journals
This study evaluated the cognitive and mood effects of peppermint essential oil, rich in menthol and menthone, on healthy adults. Participants received varying doses of the essential oil, and their cognitive performance was assessed at multiple intervals. The highest dose (100 µL) led to significant improvements in tasks requiring sustained attention and working memory, particularly at 1 and 3 hours post-administration. Additionally, participants reported reduced mental fatigue. These results suggest that peppermint essential oil may enhance attention and cognitive performance. PubMed
The Influence of Essential Oils on Human Vigilance
(2010)
This study examined the effects of inhaling various essential oils on human vigilance performance, including 1,8-cineol, jasmine absolute ether, linalyl acetate, and peppermint. Participants completed a visual vigilance task while exposed to these scents. The results indicated that linalyl acetate inhalation decreased reaction times, suggesting enhanced alertness. However, the study also highlighted the significant role of subjective factors in how olfactory stimuli modulate attentional functions, emphasizing the complexity of the relationship between scent and cognitive performance.
PubMed
Behavioral and Neural Changes Induced by a Blended Essential Oil on Human Selective Attention
(2019)
This study investigated the effects of a blended essential oil on selective attention in healthy adults. Participants performed attention tasks while their neural activity was monitored using EEG. The results showed that exposure to the essential oil blend improved performance by reducing response times and modulating P300 amplitude, a neural marker associated with attention and stimulus evaluation. Additionally, increased phase synchronization in frontal-parietal networks was observed, suggesting enhanced attention-related neural coordination.
Mood & Depression
These studies suggest that aromatherapy, particularly through inhalation and massage using essential oils, can have beneficial effects on mood and may help alleviate symptoms of depression.
Effects of Aromatherapy on Depression: A Meta-Analysis of Randomized Controlled Trials
(2023)
This meta-analysis evaluated the impact of aromatherapy on depressive symptoms by analyzing 32 randomized controlled trials. The results demonstrated that aromatherapy has a moderate effect in reducing depression, with inhalation methods and blended essential oils being particularly effective. The study suggests that aromatherapy can serve as a reliable non-pharmacological intervention for alleviating depressive symptoms.
PubMed
This study investigated the effects of diffused essential oils on stress and mood among clinical nurses. Over several weeks, different citrus essential oils were diffused in the workplace. The findings indicated significant improvements in stress, depression, and overall mood, suggesting that workplace diffusion of essential oils can positively influence mental well-being in high-stress professions.
PubMed
This randomized controlled trial assessed the impact of aromatherapy massage on depression and anxiety in elderly adults. Participants who received massages with essential oils showed significant reductions in both depression and anxiety levels compared to the control group. The study highlights the potential of aromatherapy massage as an effective intervention for improving mental health in the elderly population.
Aromatherapy for Postpartum Depression: A Systematic Review and Meta-Analysis
(2023)
This systematic review and meta-analysis examined the effectiveness of aromatherapy in managing postpartum depression. Analyzing data from multiple randomized controlled trials, the study found that aromatherapy may be effective in reducing postpartum depressive symptoms. However, the authors noted the limited number of high-quality studies and called for more robust research to confirm these findings.