To say that most of mainstream medicine is skeptical about aromatherapy – the use of essential oils distilled from plants around the globe to prevent or treat disease – would be an understatement. Most doctors would prescribe antidepressants or anti-anxiety drugs without a thought of suggesting you try inhaling citrus or lavender oil for your depression and anxiety, just as most would recommend ibuprofen or other pharmaceutical painkillers without a thought of peppermint oil for your headache.

The idea of using essential oils to treat major depression or anxiety or to ameliorate neurological conditions as serious as Alzheimer’s and Parkinson’s diseases just wouldn’t pass their sniff test. Essential oils, according to modern medicine, are sweet-smelling placebos at best and dangerous snake oil at worst, peddled to the desperately ill by quacks or through get-rich-quick pyramid schemes.

Research into essential oils has been piling up year-on-year, however, and in the past decade it has exploded. Before the year 2000, essential oils were lucky to merit 30 published studies annually. By 2012 that had climbed to 748 studies published in peer-reviewed journals, and in 2022, PubMed, the library of international medicine, carried a whopping 2,037 new studies on essential oils.

The oils of aromatic flowers and plants capture their “essence” – the volatile compounds that turn to gas quite easily at room temperature and bind to receptors in our nose.

Arabs began using essential oils (probably fermented in oil rather than distilled and concentrated like today’s oils) for both spiritual and physical healing ages ago.

In the Old Testament, God instructed Moses to blend myrrh, cinnamon, cassia and calamus in olive oil to make a fragrant, sacred anointing oil, and in the book of Esther, before a young woman’s turn to see King Xerxes, she underwent 12 months of beauty treatments, including six months of detox massages with oil of myrrh.

Later, the three wise men brought gifts of gold, frankincense and myrrh to the Christ child – the oils as prized as the gold. The Greek physician Hippocrates named the oils of aromatic plants the “father of medicines,” and they were staples of Arabic, Chinese, Ayurvedic, African and Egyptian medicine.

What’s in essential oils?

Oils like rosemary and frankincense have been used for millennia, but scientists have only just begun defining their chemical constituents and biological actions.¹

It turns out that there was more to find than expected. The humble rosemary evergreen shrub growing wild throughout the Mediterranean and in garden pots around the globe, for example, has antioxidant, antibacterial, hypoglycemic, anticancer, liver-protective, anti-inflammatory and heart-disease-fighting activities, among others.²

The boswellic acids in frankincense have anti-inflammatory traits that combat several forms of colitis, rheumatoid arthritis, osteoarthritis, Crohn’s disease and bronchial asthma and kill a range of cancer cells.³ Two case reports describe women with benign essential blepharospasm (an eye nerve disorder that can lead to blindness) improving dramatically with topical frankincense oil instead of the routine Botox injections.⁴

Cinnamaldehyde, the major phytochemical in the essential oil of cinnamon, possesses anti-inflammatory, antioxidant, anti-diabetic, blood-sugar and blood-pressure lowering, and anti-obesity properties.⁵ Oregano oil has been experimentally demonstrated to repair leaky guts in pigs by reducing E. coli bacteria and modulating the immune system.⁶

As it’s become clearer that the drugs for mood disorders and neurological conditions like Alzheimer’s are failing, researchers are turning to old remedies to develop new pharmaceuticals, fueling a research bonanza into aromatic herbs and their essential oils. These oils are composed of hundreds of biochemically active molecules that impact the immune and central nervous systems.⁷

How do they work?

“There are approximately 40 quintillion molecules in one drop of essential oil,” Jodie Cohen explains in Essential Oils to Boost the Brain and Heal the Body (Ten Speed Press, 2021). “That is a 4 with 19 zeroes after it: 40,000,000,000,000,000,000.”

These molecules are whiffed in through the nose or mouth and travel to the lungs, where they immediately enter the blood and are sent throughout the body. They penetrate the skin when applied via massage oils, the same way skin patches deliver nicotine to the bloodstream.

Once in the body, essential oils stimulate the vagus nerve, a central and critical conduit connecting the brain to every organ system in the body. This stimulation affects mood, quality of sleep and digestion, and immune function. It also critically tunes the parasympathetic system and turns off inflammation to allow healing.

Vagal tone – the adaptability of the vagus nerve – is increasingly recognized as an important venue for healing brain conditions, including Alzheimer’s.⁸

Unlike drugs, essential oil molecules can also pass directly through the blood-brain barrier via nerves in the nasal cavity, entering the central nervous system and limbic systems this way. It turns out essential oils frequently target the same pathways of brain disorders that pharmaceutical drugs do – such as inflammation and oxidation – minus the most dangerous side effects.

“Essential oils are effective on almost all currently known pathological targets of Alzheimer’s disease,” Pakistani researchers noted after conducting a recent review of the science literature. “Essential oils also possess neuroprotective, anti-aging potentials and are effective in dementia, epilepsy, anxiety and other neurological disorders.”⁹

Here is an overview of the findings for the most prevalent brain disorders: depression, anxiety, Alzheimer’s disease and Parkinson’s disease.

Depression

Depression is a staggering health problem made worse by the public health response to Covid-19. Along with anxiety, it surged 25 percent during the first year of the pandemic, bringing the worldwide total of those suffering to 280 million people.¹⁰

Depression robs people of joy and fulfillment and leads to over 700,000 suicides each year. But it’s also associated with cognitive disorders affecting attention, executive functions and memory, and it may precede dementia and Parkinson’s disease.¹¹ Doctors reach for the prescription pad for depression, but in 30 to 50 percent of people who take antidepressants according to their instructions, the drugs don’t work at all.¹²

There are side effects, too. The main class of antidepressants, selective serotonin reuptake inhibitors (SSRIs), can spike chances of fatal arrhythmia¹³ and cause symptoms from dry mouth and constipation to sexual dysfunction, emotional blunting, weight gain and suicidal thoughts.¹⁴

As Brazilian researchers noted in a recent review, “In the past decade, many studies have reported the efficiency of essential oils in relieving symptoms of diseases related to mental disorders, improving mood and feelings of physical and mental well-being, with the advantage of fewer adverse reactions.”¹⁵

The essential oils below may be useful for treating depression.

Citrus These citrus essential oils have been studied for their potential ability to lift depression:

• Bergamot (Citrus bergamia)
• Lemon (Citrus limonum)
• Sweet orange (Citrus sinensis)

In one study, researchers at the Department of Psychiatry at Mie University School of Medicine in Japan examined the effects of essential oils on mice. Then they explored how a citrus mixture of lemon oil, orange oil, bergamot and cis-4-hexenol (an earthy green scent) affected neuroendocrine hormone levels and immune function markers in 12 hospitalized men with major depressive disorder.

The men were subjected to continuous air diffusion of the oils until remission (which took four to 11 weeks) and compared to eight control patients who received antidepressants only. Hormone and inflammatory markers almost normalized in the treatment group, and these men showed better results than the antidepressant group. Nine of 12 came off antidepressants entirely.¹⁶

A few citrus and other essential oils may cause reactions in sunlight. See “Avoid photosensitization” below for the National Association for Holistic Aromatherapy’s guidelines on avoiding photosensitivity reactions.

Lavender (Lavandula angustifolia Mill.) One of the most researched essential oils for mood, lavender oil is rich in linalool and linalyl acetate, which have antidepressant, anti-anxiety effects and have been shown to improve sleep, beneficial to both conditions.¹⁷

In one pilot study, 28 postpartum women diagnosed with mild to moderate depression or anxiety were randomized into two groups. One received standard treatment, and the other received treatment plus inhaling an essential oil blend of lavender and rose (Lavandula angustifolia Mill. and Rose otto, Rosaceae) for 15 minutes or rubbing on a hand cream twice a week for four consecutive weeks.

The essential oils significantly improved the women’s scores on the Edinburgh Postnatal Depression Scale (EPDS) and the Generalized Anxiety Disorder Scale (GAD-7) without adverse effects.¹⁸

Cinnamon oil (Cinnamomum verum) Fifteen different compounds have been identified in this oil, and the principal component (65–85 percent of its composition) is trans-cinnamaldehyde, which inhibits the release of pro-inflammatory molecules, in turn dialing down anxiety and depression.¹⁹

Patchouli (Pogostemon cablin) contains a molecule called patchoulol, a sesquiterpene demonstrated to have antidepressant activity via its effect on dopamine pathways in the body.²⁰

Anxiety

There is a lot of overlap in the research on essential oil use for depression and anxiety, in the same way that the conditions themselves often travel together. The essential oils that bring benefit for anxiety are also those for depression and good sleep. Below are a few of the oils that researchers have studied the most.

Citrus and jasmine (Citrus aurantium L. and Jasminum sambac) A meta-analysis that included 44 randomized controlled trials (50 study arms) involving 10 kinds of essential oils and 3,419 anxiety patients concluded that the most evidence from anxiety scales plus blood pressure and heart rate measurements was for citrus (Citrus aurantium L.), followed by jasmine oil, which was tops when differences were weighted.

Damask rose oil (Rosa rugosa Thunb.) showed a moderate improvement, as did lavender oil.²¹

Ylang ylang (Cananga odorata) About 150 compounds have been identified in this essential oil. Its mood-adjusting and relaxing effects have been attributed to beta-caryophyllene, benzyl benzoate, linalool and benzyl alcohol in the oil.²²

One study involved 15 healthy men in a closed room where three drops of ylang ylang oil were added to a warm water lamp maintained at 90 °C. Their heart rate and blood pressure, measured before exposure and one hour after, significantly decreased, and their autonomic nervous system calmed.²³

Another study, published in 2018, showed that inhaling ylang ylang essential oil in an anxiety-model of mice was linked to altered blood serotonin, reduced corticosterone in blood plasma (a measure of stress) and calming effects in the hippocampus.²⁴

In one recent study, 44 patients admitted to the hospital for their first radiation procedure were randomly divided into two groups. The first group received ylang ylang oil drops on two pieces of mulberry paper attached to the shoulder of their hospital gown overnight, and the second group received papers with only distilled water.

Morning salivary cortisol levels (a measure of stress) were significantly lower in those who got the ylang ylang paper than in the controls. The participants had better scores on an anxiety quiz than the distilled water group as well.²⁵

Lavender (Lavandula angustifolia) Several studies have shown that aromatherapy based on linalool-rich essential oils, such as lavender, bergamot and orange, targets GABA receptors and has an anti-anxiety effect.²⁶

Valerian (Valeriana officinalis L.) Some dentists use this oil in place of dangerous benzodiazepine drugs to calm patients before oral surgery.²⁷

Lemongrass (Cymbopogon citratus) Lemongrass oil is an old staple for treating anxiety in folk medicine. In at least one study, it has shown promise for treating anxiety in humans.²⁸

Recent studies in animals have confirmed it influences GABA pathways in the brain and normalizes behavior in mice models of social stress. This has led researchers to conclude that it may “mitigate psychosocial stress-induced neurologic diseases in susceptible individuals.”²⁹ Bear in mind that findings from animal studies may not apply to humans (see “The Real Guinea Pigs,” Nov/Dec 2023).

In one eight-week study published in 2020, researchers at the University of West Virginia School of Nursing provided aromatherapy patches to 19 nurses who worked in the Infusion Center at the school’s cancer institute. The patches were infused with a citrusy blend of lemon, orange, mandarin, pink grapefruit, lemongrass, lime and peppermint oils and worn around their necks on lanyards.

Besides reporting that the smell made them happy, the nurses reported 40 percent lower anxiety. Their fatigue fell by 40 percent after wearing the lanyards, and their feelings of being overwhelmed were cut in half, they said.

Oncology nursing is a stressful job, said Laurie Theeke, head nurse at the West Virginia nursing school. “You’re dealing with life or death or chronic illness every day. This doesn’t just have application to nursing. It’s about workplace stress.”³⁰

Jodie Cohen recommends deep breathing in a 4-4-8 pattern to activate your parasympathetic system and engage your vagus nerve to get rid of anxiety:

1. Breathe in for a count of four.
2. Hold for a count of four.
3. Breathe out for a count of six or eight.
4. Repeat

Alzheimer’s and dementia

Alzheimer’s is the most common and dreaded form of dementia that kills brain cells, robbing people of their memory and cognitive ability. The World Health Organization estimates that it affects over 55 million people worldwide, and by 2030, that number will soar to 78 million.

There is no drug to prevent or stop the progression of Alzheimer’s disease, though doctors prescribe cholinesterase inhibitors like donepezil, rivastigmine and galantamine to reduce behavioral symptoms. These drugs prevent cholinesterase from breaking down acetylcholine, an important neurotransmitter in memory. But their side effects are considerable, ranging from nausea, vomiting and insomnia to confusion and seizures.

A 2020 Cochrane review on essential oils for dementia found that the existing human trials were too small or too poorly controlled to conclude that the oils can benefit those with dementia. Since essential oils cannot be patented, there is little incentive to do the costly large clinical trials required.³¹

However, more recent studies have confirmed that certain essential oils have potent anticholinesterase activity similar to the drugs in common use, but without the side effects and with the benefit of active components that can penetrate the blood-brain barrier more effectively. Others have been shown to induce benefits through other mechanisms, such as their antioxidant capacity.³²

Here are a few of the most promising essential oils in Alzheimer’s research today.

Rosemary (R. officinalis) A 2022 study of different forms of rosemary extract concluded that it contains important chemical molecules, such as rosmarinic acid and carnosic acid. These substances have both antioxidant and anticholinesterase activity, validating rosemary extract’s use in traditional medicine for cognitive disorders such as Alzheimer’s.³³

Another 2022 review paper looked at 15 studies of the effect of rosemary on cognition in lab animals and concluded that while the results were unpredictably mixed, “overall, it improved cognitive outcomes in normal and impaired animals, and results were robust across species, type of extract, treatment duration, and type of memory.”³⁴

While that study may not apply to humans, small human trials have confirmed its effectiveness. For example, rosemary essential oil sprayed in the air significantly increased image and number recall of students compared to controls with no rosemary exposure.³⁵

Bay laurel (Laurus nobilis) A September 2023 study looked at the effect of the essential oil from bay laurel – the plant grown since Roman times and featured as Olympic wreaths – on mice with memory damage induced using the drug scopolamine (used in mainstream medicine to treat conditions including nausea).

The mice treated with essential oil of bay laurel showed enhanced cognitive performance and antioxidant status compared to controls that didn’t receive the oil and were protected against damage from the drug.³⁶

Saffron (Crocus sativus) Recent studies have highlighted a possible link between chronic stress, cognitive decline and its progression to Alzheimer’s disease.

Saffron is the world’s most expensive spice today, the dried red thread-like stigma hand-plucked from the autumn crocus flower. It has long been used in traditional Tibetan medicine, and recently safranal, one of its active components, was demonstrated to have anticancer action against glioblastoma brain cancer.³⁷

Some of its other components, especially crocin, have been shown to combat stress-induced cognitive dysfunction and oxidative stress and to slow decline in Alzheimer’s disease. Crocin is antioxidant, antidepressant and anti-inflammatory, and it prevents acetylcholinesterase from breaking down acetylcholine.

As well, saffron has been shown to tighten the blood-brain barrier and to prevent aggregation of the beta-amyloid protein that makes up the hallmark plaques in the brains of Alzheimer’s victims.³⁸

Peppermint (Mentha piperita) Researchers at the University of Northumbria found that people exposed to peppermint oil in the air had increased memory recall and alertness performance on tests.³⁹

Parkinson’s disease

Like other brain conditions, Parkinson’s disease is thought to be driven by inflammatory and oxidative processes, so it may benefit from the anti-inflammatory oils described above, such as frankincense.⁴⁰ But curcumin, a component of the turmeric root, has thousands of studies supporting its anti-inflammatory abilities, and new research is looking into it for Parkinson’s disease therapy.

Turmeric (Curcuma longa) Japanese researchers recently showed that the main component in turmeric essential oil, called ar-turmerone, “potently protected dopaminergic neurons,” the brain cells that produce the neurotransmitter dopamine. The cells are under attack in Parkinson’s patients, causing their tremors, muscle stiffness and other symptoms.

The Japanese scientists believe aromatic ar-turmerone reduces inflammation in microglia, the brain’s immune cells, and relieves oxidative stress.⁴¹

Using essential oils safely

When inhaled or used topically according to the correct dilution, essential oils are very safe. Serious side effects are sensitivity reactions when the oils are applied topically in strong dilution or when they’re ingested. The oils themselves are so potent – one drop of peppermint essential oil is the equivalent of 25 cups of peppermint tea – they should not be ingested except under specific guidance and dilution.

Because they are so concentrated, some essential oils can be deadly. For example, a 5-mL bottle of wintergreen could kill a child if ingested because it contains about 7,000 mg of salicylate (the equivalent of 20,350 mg worth of aspirin tablets).⁴²

When using essential oils, never take their potency lightly. Refer to the standard dilution guidelines (see “How to dilute essential oils for safe use”) based on age and find out whether the oils you want to use come with any extra precautions. The National Association of Holistic Aromatherapy is a good source of vital safety information.

Essential oil recipes

Mama Z’s Mood and Depression Roll-on Relief

Sabrina Zielinski, also known as Mama Z, and her husband Eric Zielinski offer a wealth of information on essential oils research and use on their website Natural Living Family (naturallivingfamily.com), including books, programs and free essential oil recipes like this one to banish dark moods.

Ingredients

• 1 drop lemon essential oil
• 1 drop bergamot oil
• 1 drop ylang ylang oil
• 1 drop frankincense oil
• 1 drop lemon balm (Melissa) oil
• 1 drop lavender oil
• 10 mL carrier oil of your choice, such as jojoba, olive, coconut, argan or almond oil
• 10-mL amber glass roll-on bottle

Method

1. Add one drop of each essential oil for mood balance to the bottle.
2. Add your favorite carrier oil to fill the bottle.
3. Mix the essential oils and carrier oil in the bottle by rolling it between your palms.
4. Apply to pulse points. (CAUTION: See “Avoid photosensitization,” about avoiding sunlight reactions with bergamot and other essential oils.)

If you prefer a mood-lightening room spray, mix 4 drops each of the essential oils above into a 2-oz spritzer bottle and fill it up with 190-proof alcohol.

Diffuse anxiety with a calming oil blend

Aromatherapist Jennifer Lane of San Jose, California, offers this recipe on her website (lovingessentialoils.com) to relax anxious nerves.

Ingredients

• 2 drops lavender oil
• 2 drops bergamot oil
• 2 drops rose oil
• 2 drops ylang ylang oil

Method

Add drops of essential oils to your diffuser with the recommended water for your machine. Relax and enjoy.

Jodie Cohen’s Focus Blend

Cohen says just opening a bottle of rosemary or peppermint for a whiff is a good way to start with essential oils. She offers the recipe below to enhance focus and cognition.

Ingredients

• 8 drops peppermint oil
• 8 drops rosemary oil
• 6 drops basil oil
• 2 drops cardamom oil
• 1 oz carrier oil

Method

Dab directly over your temples and on the back of your neck and massage.

Turmeric essential oil muscle aid

Monika Pearson, who runs the (Essential Oil Adviser), offers this turmeric essential oil recipe.

Ingredients

• 4 drops turmeric essential oil*
• 15 drops peppermint oil
• 15 drops lavender oil
• 2 tsp ground cayenne pepper
• ½ cup coconut oil
• ¼ cup grated beeswax

Method

1. Put beeswax and coconut oil into a glass jar. Place the jar inside a pot and fill the pot with 2 inches of water.
2. Heat the pot over medium-low heat to melt the wax and coconut oil. Stir the ingredients thoroughly.
3. Remove from heat, stir in the cayenne and allow the mixture to cool.
4. Add essential oils. Pour the mixture into a storage container and allow it to set.

*People on blood-thinning medication, such as warfarin and aspirin, and those with gallbladder issues and kidney stones should avoid using turmeric essential oil. People on medication for hypertension or hemophilia should consult their medical specialist about using turmeric essential oil. Turmeric oil may temporarily stain skin.

Avoid photosensitization

A few essential oils will cause burning or pigmentation changes when applied to skin and exposed to sun or ultraviolet rays from tanning beds.

“Reactions can range from a mild color change through to deep weeping burns,” warns the National Association for Holistic Aromatherapy (naha.org). The organization advises staying out of the sunshine and sunbeds for at least 24 hours after a treatment with the photosensitizing essential oils below.⁴³

Photosensitizers

Essential oil	Latin name
Angelica root	Angelica archangelica
Bergamot	Citrus bergamia
Cumin	Cuminum cyminum
Grapefruit, distilled or expressed (low risk)	Citrus paradisi
Lemon, expressed	Citrus limon
Lime, expressed	Citrus medica
Bitter orange, expressed	Citrus aurantium
Rue	Ruta graveolens

Non-phototoxic citrus oils

Essential oil	Latin name
Bergamot, bergapten free or furanocoumarin free (FCF)	Citrus bergamia
Lemon, distilled	Citrus limon
Lime, distilled	Citrus medica
Mandarin/tangerine	Citrus reticulata
Sweet orange	Citrus sinensis
Tangerine, expressed	Citrus reticulata
Yuzu, expressed or distilled	Citrus juno

How to dilute essential oils for safe use

To make your own therapeutic products at home, dilute essential oils by adding them to a less potent carrier oil, such as jojoba, olive, coconut, argan or almond oil. Follow these guidelines to ensure safe use (1 oz = 2 Tbsp).⁴⁴

	Concentration	Drops of essential oil per oz carrier oil	Drops of essential oil per Tbsp carrier oil
Infants/children	0.5%	3	1.5
	1%	6	3
Adults	2%	12	6
	3%	18	9
	5%	30	15
	10%	60	30