< Trial Description and Rationale for Intervention >
Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD),
Lewy body dementia (LBD), and frontotemporal dementia (FTD) are major causes of cognitive
decline, with AD being the most prevalent. Dementia is characterized by cognitive
impairment, memory deficits, and neuropsychiatric symptoms, leading to loss of
independence and increased caregiver burden. Current pharmacological treatments can only
slow disease progression, with no curative therapy available.
The pathogenesis of neurodegeneration involves multiple mechanisms, including
amyloid-beta (Aβ) aggregation, tau protein hyperphosphorylation, neuroinflammation,
oxidative stress, and cholinergic dysfunction. Neuroinflammation, primarily mediated by
microglia and astrocytes, plays a central role in neuronal damage. Dysregulated microglia
contribute to synaptic dysfunction, while pro-inflammatory astrocytes promote neuronal
apoptosis through the NF-κB pathway. Oxidative stress exacerbates neurodegeneration by
inducing mitochondrial dysfunction and increasing reactive oxygen species (ROS), which
further promote Aβ accumulation and tau pathology.
Mild cognitive impairment (MCI) represents an intermediate stage between normal cognition
and dementia. Approximately 25 percent of individuals with MCI progress to dementia
within two years, while others may recover cognitive function. Current interventions,
including cholinesterase inhibitors, dietary supplements, and exercise, have shown
inconsistent results. Given the multifactorial nature of MCI and the potential for
cognitive recovery, exploring alternative neuroprotective therapies is essential.
Olfactory dysfunction is an early biomarker of neurodegeneration, as the olfactory nerve
directly connects to the limbic system, which regulates memory and emotion. Aromatherapy,
the therapeutic use of essential oils, has been investigated for its effects on cognitive
function. Studies on cellular and animal models have demonstrated that essential oils
exert neuroprotective effects through multiple mechanisms, including reducing Aβ-induced
neurotoxicity, modulating microglia-mediated neuroinflammation, regulating glutamate and
GABA neurotransmission, and inhibiting tau hyperphosphorylation via glycogen synthase
kinase-3β (GSK3β) suppression. Essential oils also activate cAMP response element-binding
protein (CREB) signaling, enhance antioxidant defense by increasing superoxide dismutase
(SOD) levels, reduce pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6, and
modulate brain-derived neurotrophic factor (BDNF) expression. Additionally, they prevent
neuronal apoptosis and mitochondrial dysfunction, inhibit acetylcholinesterase (AChE)
activity, and enhance synaptic plasticity and neurotransmitter balance.
Several essential oil constituents, including 1,8-cineole, linalool, limonene, thymol,
alpha-humulene, cis-carveol, alpha-pinene, beta-pinene, rosmarinic acid, and zingerone,
have demonstrated neuroprotective properties. These compounds may contribute to cognitive
enhancement by reducing neuroinflammation, oxidative stress, and synaptic dysfunction.
Based on this hypothesis, the investigators formulated a natural essential oil blend rich
in 1,8-cineole, linalool, limonene, and other bioactive compounds, and applied it via
inhalation as an intervention. Using the concept of olfactory training and targeting the
limbic system, the study aims to evaluate whether essential oil inhalation can promote
improvements in cognition, memory, sleep, mood, and quality of life in individuals with
MCI. The effects will be assessed through validated clinical scales and by measuring
urine and serum biomarkers related to neuroinflammation. Additionally, changes in
meridian energy and autonomic nervous system activity will be monitored. The goal is to
provide a convenient and supportive complementary therapy for individuals with MCI,
offering clinicians an evidence-based option for early intervention in cognitive decline.
< Study Procedures and Design Rationale>
This study is a randomized, double-blind, parallel-group clinical trial designed to
evaluate the effects of CXMCI-01 essential oil inhalation on cognitive function in
individuals with mild cognitive impairment (MCI). A total of 100 participants will be
enrolled and randomly allocated in a 1:1 ratio to either the experimental group or the
control group.
Randomization will be conducted using a computer-generated sequence, and allocation will
be concealed using opaque, sealed envelopes. Each participant will receive a sequential
identification number. The randomization process and distribution of the essential oil
formulations will be managed by a third party who is independent of the study procedures
to ensure blinding.
Participants will be recruited through neurology outpatient clinics at China Medical
University Hospital, Chung Shan Medical University Hospital, and Everan Hospital. Those
who meet preliminary eligibility will undergo final screening and informed consent at
Everan Hospital.
The study consists of three scheduled visits:
Visit 1 (V1): Baseline assessment prior to intervention.
Visit 2 (V2): Post-intervention assessment after 28 days of essential oil
inhalation. A visit window of + 5 days from the scheduled date is acceptable.
Visit 3 (V3): Follow-up assessment conducted 28 days after the completion of the
observation period. A visit window of ±5 days is also acceptable.
The essential oil intervention includes two types of blended formulations, each prepared
in two concentrations (100% and 0.1%):
CXMCI-01-M: A blend containing lemon, rosemary (1,8-cineole type), rose geranium,
and sweet marjoram essential oils.
CXMCI-01-N: A blend containing frankincense, true lavender, linalool, and
ylang-ylang essential oils.
The control group are diluted to 0.1% concentration using a neutral carrier oil.
Participants will perform inhalation twice daily for 28 consecutive days. And use twice
daily. The essential oil intervention was designed with consideration of the body's
natural circadian rhythm. The autonomic nervous system exhibits daily fluctuations, with
sympathetic activity typically dominant in the morning and parasympathetic activity more
prominent at night. Cortisol levels also follow a diurnal pattern, peaking in the early
morning and gradually declining throughout the day. To align with this physiological
rhythm, the morning formulation (CXMCI-01-M) was selected to support alertness and
sympathetic activation, while the evening formulation (CXMCI-01-N) was intended to
promote relaxation and enhance parasympathetic activity. This time-specific approach aims
to optimize the neurophysiological effects of essential oil inhalation, supporting both
cognitive performance and overall well-being.
In the morning, 2 drops of the assigned essential oil (intervention group with 100%
formula, placebo group with 0.1% formula) will be applied to a cotton pad.
Participants will first inhale the aroma near the nose for 5 minutes before placing
the cotton pad in an aroma necklace, which will be worn for an additional 60
minutes.
The same procedure will be repeated at night with a different formulation.
The experimental group will receive the 100% CXMCI-01 formulations (CXMCI-01-M in the
morning and CXMCI-01-N at night), while the control group will receive the 0.1% diluted
versions of the same formulas.
To ensure consistency, participants will be instructed to avoid interfering factors
during inhalation, such as eating, drinking strong-smelling beverages, smoking, or being
in scented environments. Concurrent use of other essential oils, perfumes, or
cognitive-enhancing treatments will be restricted throughout the study period.
This structured inhalation protocol, utilizing specific essential oil compositions with
known neuroprotective properties, is designed to target neuroinflammatory and oxidative
mechanisms through the olfactory-limbic pathway. The study aims to explore whether this
intervention can support cognitive, emotional, and physiological well-being in patients
with MCI.
Throughout the study period, participants or their caregivers will be asked to maintain a
daily log, recording aromatherapy usage, sleep patterns (including bedtime, time to fall
asleep, and wake-up time), physical activity (type and duration), and dietary habits.
Specific attention will be given to the intake of refined sweets, sugary beverages, and
fried or grilled foods. Participants will also document any acute medical events, such as
hospital visits, medication use, and symptoms of upper respiratory infections. Any
adverse reactions potentially related to essential oil use, such as dizziness,
palpitations, or asthma-like symptoms, will be reported in the log.
Following the post-intervention assessment, participants will continue to maintain their
daily tracking logs as previously instructed. A follow-up evaluation will be conducted
within 28 ± 5 days after the completion of the intervention to examine the sustained
effects of the essential oil inhalation.
The follow-up assessments will include a combination of clinical, cognitive,
psychological, and physiological evaluations. Cognitive assessments will include the
Contextual Memory Test (CMT), a standardized tool for assessing episodic memory in
real-life contexts; the Montreal Cognitive Assessment (MoCA), commonly used to screen for
mild cognitive impairment; and the Taiwan Odd-Even Number Sequencing Test (TOENST), which
evaluates working memory and processing speed.
Psychological and quality of life assessments will include the Pittsburgh Sleep Quality
Index (PSQI), Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and the
36-Item Short Form Health Survey (SF-36), which collectively assess sleep quality,
emotional well-being, and overall health-related quality of life.
To explore the potential biological effects of the essential oil intervention, blood
samples will be collected for biomarker analysis. These may include markers related to
amyloid and tau protein pathways, such as the Aβ42/40 ratio, total tau protein, and
phosphorylated tau protein-217 (p-tau 217), which are commonly associated with
neurodegenerative processes and Alzheimer's disease pathology. Including these biomarkers
will allow for an exploratory evaluation of possible changes in biological mechanisms
relevant to cognitive decline and mild cognitive impairment.
In addition to blood-based markers, urinary biomarkers related to neuroinflammation will
also be assessed at baseline and post-intervention. These may include lipid peroxidation
(LPO) and 8-hydroxy-2-deoxyguanosine (8-OHdG), quinolinate, kynurenine, kynurenate, and
picolinate. These biomarkers are involved in oxidative stress, mitochondrial function,
and neuroimmune activity, and may provide further insights into the systemic biological
response to the intervention.
Physiological assessments will include non-invasive testing using the Meridian Energy
Analysis Device (M.E.A.D.) to evaluate meridian energy distribution, and heart rate
variability (HRV) testing to assess autonomic nervous system function. These
comprehensive follow-up evaluations aim to assess the longer-term impact of CXMCI-01
essential oil inhalation on cognitive function, emotional status, sleep quality,
biological markers of neuroinflammation and neurodegeneration, and systemic physiological
regulation.
To minimize variability, participants will follow dietary and lifestyle restrictions
before each testing session. This includes avoiding excessive oily food and refined
carbohydrates for three days before testing and refraining from alcohol or caffeinated
beverages the day before. Morning urine samples will be collected on scheduled days, and
female participants will be asked to avoid urine collection during menstruation.
This comprehensive assessment protocol aims to evaluate not only cognitive changes but
also neuroinflammatory markers, autonomic nervous system function, and energy regulation
in response to essential oil inhalation.
< Study Summary and Expected Impact >
This randomized, double-blind, parallel-group trial is designed to evaluate the effects
of CXMCI-01 essential oil inhalation on cognitive function in individuals with mild
cognitive impairment (MCI). By integrating daily olfactory stimulation based on circadian
rhythm, this study aims to explore whether specific essential oil formulations can
influence neuroinflammation, oxidative stress, and autonomic function to support
cognitive health.
Through a comprehensive multimodal assessment, including cognitive evaluations, biomarker
analysis, and physiological testing, this study will generate valuable data on the
potential of essential oil-based interventions as a complementary approach to MCI
management. The findings may contribute to future clinical applications by providing an
evidence-based strategy for cognitive enhancement and neuroprotection.