Introduction

Smell is the most mysterious and evocative of our senses: it is our chemical sense, informing us about the surrounding environment and giving information that is not tangible, visible or audible. This chapter explores the connections between a person’s thoughts, feelings and immune status, and suggests that the ability of essential oils to affect all these via the sense of smell makes aromatherapy a truly holistic therapy.

The impact of the mind and emotions on the body

Throughout the ages people concerned with healing have been aware that there is a connection between thoughts, emotions and the state of health of the physical body. The British Medical Journal in 1884 observed that ‘the depression of the spirits at these melancholy occasions (funerals) … disposes them to some of the worst effects of the chills’ (Wood 1990a). These effects can be real, and changes in blood chemistry have been recorded even when the emotions are conjured up artificially, as in the case of superstition. Three thousand years ago the impact and influence of the intangible human mind on the material body was recorded in the Old Testament: ‘A merry heart doeth good like a medicine; but a broken spirit drieth the bones’ (Proverbs 17: 22, King James version).

In modern times this has been recognized not only by psychotherapists and those in psychosomatic medicine, but also in general medicine.

Psychoneuroimmunology (PNI)

In the past the psyche, the nervous system and the immune system were studied more or less as independent systems functioning alongside each other, but without direct connections. The science of PNI attempts to understand how the brain and the immune system communicate with each other,

PNI is also referred to as psychoendoneuroimmunology (PENI).

The immune system

Neuropeptide messengers produced by the immune system, brain and nerve cells provide two-way communication between the emotional brain and bodily systems via hormonal feedback loops. The limbic system (hypothalamus and pituitary), the spleen, the adrenal and thymus glands all have nerve interconnections. Thus emotions are capable not only of directing the body but also of receiving and being modified by information feedback from cells in the body.

Adrenalin and cortisol are two of the many chemical messengers whose release can be triggered by negative emotion in sudden or long-term stress: these two hormones influence the immune system directly to switch it off (Borysenko 1988 p. 14). Adrenocorticotrophic hormone (ACTH) suppresses pituitary action by stimulating the adrenal gland to produce adrenaline (epinephrine), which is a stimulator of the autonomic nervous system (ANS). The idea has gradually gained ground that emotional states can translate into altered responses in the immune system: negative thoughts and sad emotions can sometimes temporarily lessen the effectiveness of the immune system. Hence the body puts non-material thoughts and emotions into physical effect, either to produce a beneficial healing effect or to inflict self-damage. This idea is echoed by many writers.

The effect of the emotions on health

It has not yet been possible for anyone to show a link between a particular emotion and any specific physical disease – ‘Pessimism is not linked to any particular disease’ (Wood 1990b) – although pessimism or depression amplify symptoms of pain. It can probably be said that the course of nearly all disease is affected by thoughts, feelings, emotions and attitudes, which are in turn influenced by personality.

Thinking and healing

Using the mind to control pulse rate and breathing, and to bring about general relaxation of the body, has long been practised in different cultures. In the meditative state the brain waves drop from the β rhythm to the slower α rhythm; the blood circulation is diverted more to the brain and vital organs, with less going to the muscles, so that the heart rate is slower, blood pressure is lower and little oxygen is used.

All this is initiated by thought alone, effected via the hypothalamus. Hesse, experimenting on cats in the 1950s, found that when the hypothalamus was stimulated, increased activity or relaxation was produced (Hesse & Akerl 1955). Sometimes, in people suffering a terminal illness, this mind-to-body effect can make healing possible even though a cure is not.

It is now realized that for optimum healing the sufferer must be fully involved in all stages of the treatment, from diagnosis to final cure, and that all true healing comes from within. Healing is accomplished by mental and physical routes, with primary roles played by the patient, doctor and nurse, while family and friends take secondary supportive parts. As Plato wrote in the third century BC:

Trust and placebo

Another well-known example of the effect of thought on the physical body is the placebo effect. This happens when the cure or amelioration of an illness is due to the patient’s trust and belief in a prescribed substance, to faith in the healer, or frequently a combination of both. Dummy painkillers are 56% as effective as morphine in the treatment of severe chronic pain (Chaitow 1991). This remarkable and much-used placebo effect is important in all healing: when people are made to feel better, positive healing thoughts, which encourage the healing process, are generated. If an aromatherapy treatment does no more than make people feel better in themselves, it puts the whole person into healing mode.

‘Immunity is to some degree under mental control’ (Wood 1990a). Just as positive healing thoughts induce healing reactions in the body, the efficiency of the immune system is reduced by negative beliefs and thoughts. Immunity from disease appears to be enhanced or diminished by beliefs, and by the environment in so far as it affects our emotions. Fortunately, the human race is intrinsically optimistic, with a will to survive.

Where does aromatherapy fit in?

How can aromatherapy play an effective and worthwhile part in the mental–physical sphere of healing? It is established beyond doubt that essential oils can have physical impact in that they are bactericidal, anti-inflammatory, antifungal, appetite stimulating, hyperaemic, expectorant etc. (see Ch. 4 and Table 7.1). They possess properties which can affect the mind and emotions to sedate, calm and uplift; they also have effects on bodily systems, they evoke memories, change perception, calm agitation, relieve stress, activate cognitive responses and affect intercommunication (Cook 2008, Ouldred & Bryant 2008). They are therefore ideal tools for tackling not only physical problems but at the same time mental and emotional states, working via the sense of smell.

Table 7.1 Effects of essential oils used internally and externally (from Schilcher 1984)

The placebo effect (expectations effect) is another factor that may influence the effect of an aroma on human behaviour, mood and health:

Relaxation response

When safe and calm, people experience the opposite of the stress response, in that tension, blood pressure, oxygen use and so on are reduced. This has been termed the ‘relaxation response’ (Benson 1975). It can be brought about by many means, including reading, listening to favourite music, contemplating nature – and aromatherapy.

When, during a massage, the touch of the therapist is combined with the mental and physical effects of the essential oils, the client is helped to achieve a temporary separation from worldly worries, somewhat akin to a meditative state. The massage itself induces the relaxation response, which activates the body’s healing mode, and this, in conjunction with the essential oils, is outstanding for the relief of tension and anxiety, both physical and mental.

Whatever the method of application, the authors feel that in many cases most of the healing effect of essential oils is primarily through inhalation (see Ch. 6) via the mind and emotional pathways, and that a lesser part takes place via the physical body. There is no doubt that smelling plant volatile oils can affect the mood and general feeling of wellbeing in the individual. This is especially true when the essential oils are applied with whole-body massage: the physical and mental relaxation achieved during a massage session has to be experienced to be appreciated. To select essential oils to address the mental, emotional and physical needs of the client, the cause(s) of the health

Pregnancy and children

The influence of odours on humans begins even before birth; the odour of anise was presented to 24 neonates and it was shown that babies born to mothers who consumed anise during their pregnancy showed a stable preference for the smell, whereas babies born to non-anise consuming mothers showed aversive or neutral responses (Schaal et al. 2000).

A report by Nordin et al. (2004) showed that abnormal taste and smell was reported by 76% of 187 pregnant women tested, typically believed to be caused by their pregnancy. Increased smell sensitivity was common during the early stages of pregnancy (67%), occasionally accompanied by qualitative smell distortions (17%) and phantom smells (14%). Smell abnormalities occurred less in later periods of pregnancy and were virtually absent after delivery. Abnormal taste sensitivity was fairly commonly reported (26%), often described as an increase in bitter and a decrease in salt taste. Pregnancy smell and taste disorders relate to fetal protection mechanisms to avoid poisons and increase salt levels for the expanded fluid levels.

Anecdotal evidence indicates that during pregnancy olfactory sensitivity is increased, and the lack of scientific evidence to back this up was investigated (Cameron 2007). One hundred women who did not smoke were tested and the overall conclusion was that the effect of pregnancy was small and inconsistent, but interestingly the women felt that they had heightened awareness of smells during their pregnancy.

Adding the aroma of lemon to a classroom helps to involve all the senses in the learning experience, and Chu (2008) says that low-achieving school-children experienced success in a written task in the presence of an ambient odour (herbal tea), and when they experienced this same odour in a later task they were shown to be significantly better than a relevant control group. Chu claims that this is the first study to show a classic conditioning effect to influence human behaviour (but see Aromas, Memory and Mood, below).

The sense of smell is important in children with severe learning difficulties (see Ch. 13) who may have diminished hearing and sight, and essential oils can be used to make their life easier and more friendly. Fragrances have been used on wristbands to identify carers, each with their own aroma, to identify the child’s possessions and to locate areas, rooms and facilities (Sanderson, Harrison & Price 1991). This technique can also be used to make a baby sitter acceptable to the child.

The elderly

Aromas are well accepted in homes for the elderly, where they can create a pleasant atmosphere, either stimulating or relaxing, and some aromas may create an ambience which will bring back memories, possibly sparking off nostalgic conversation between the residents, with obvious benefits (see Ch. 14).

Gender differences

There appears to be a gender difference in the impact on the mind of inhaled essential oils, as it seems that women are the more likely to derive beneficial results. One study indicating this was the use of Citrus sinensis [sweet orange] diffused into the waiting room of a dental practice, where the results of a questionnaire filled in by patients of both genders showed that sweet orange oil had a relaxant effect compared to non-odour controls. Compared to men, women had a lower anxiety state, a more positive mood and higher level of calmness. The typical smell of dental premises, eugenol, was associated with anxiety and fear, although this was masked for women by the orange aroma, lowering their anxiety; for men this was only minor (Lehrner et al. 2000).

Another study set out to demonstrate the gender effect of odour on pain perception: 20 men and 20 women were exposed to pain by holding a hand in hot water while smelling previously selected odours. Separate analyses for men and women revealed a significant effect of odour on pain perception for women but not for men, and when the odour was found to be pleasant women demonstrated a significant reduction in pain perception (Marchand & Arsenault 2002). The gender difference was shown in a different light when subjects proofread pages of text containing misspelt words: all participants performed significantly better when aroma was present in the room; lavender produced the greatest effect on women, whereas peppermint had the greatest effect on men (Kliauga, Hubert & Cenci 1996).

Miyazaki, Motohashi & Kobashaya (1992a) investigated the effects on females of inhalation of orange oil (unspecified), Chamaecyparis taiwanensis lig. [hinoki] and menthol, and found an increase in speed performing a mental task and a decrease in the number of mistakes for all three aromas. Profiles of mood state (POMS) scores indicated that depression/dejection, anger/hostility and tension/anxiety decreased after inhalation of the oils, whereas fatigue scores tended to increase.

A similar study explored the effects of inhalation of orange oil (unspecified), Chamaecyparis taiwanensis lig. [hinoki] and eugenol on the mood of six male individuals, and POMS were monitored: blood pressure showed a decrease after inhalation of hinoki or orange oils, but an increased heart rate with eugenol. Eugenol was deemed to be unpleasant and scores indicated increases in fatigue, depression/dejection, confusion and anger/hostility and a decrease in vigour, whereas inhalation of hinoki oil had the opposite effect (Miyazaki, Motohashi & Kobashaya 1992b).

Pleasant smells give pleasure and feelings of self-esteem (Baron 1990, Nezlak & Shean 1990) and the effect on women may be greater because, according to Herz and Cupchik (1992), women have more intense odour memories than men.

Although it is understood that personality can bias sensory perception, Chen and Dalton (2005) say that the emotional state of a person has a similar effect. Subjects were exposed via video clips to prime happiness, sadness, negative/hostility and neutral feelings. The time taken to detect odours (suprathreshold odours of pleasant, unpleasant and neutral) and the intensity of the odours was recorded. It was found that females reacted faster to smells with emotional links than to neutral smells. Emotional states augmented the intensity of odours for males.

The skin of women is more permeable than that of men to toxic chemical molecules having a similar size to those of essential oil compounds, and they can retain more fat-soluble compounds in their body and so are affected more (Eisberg 1983).

It is interesting to note that almost all practising aromatherapists and users of aromatherapy products are women, only about 2% of men being involved: this is perhaps because the overall effects of essential oils on women are more significant than on men.