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Annals of Psychophysiology                                                                                                        Volume 3, October 2016                  
©Advance Educational Institute & Research Centre                                                                    www.aeirc-edu.com 

ISSN 2412 - 3188 
 

Review Article 

Of Scents and Brain: Olfactory Stimulation for Neuropoeisis 

and Intervention for Neurodegenerative Disorders 

Alvira Ali 

Advance Educational Institute and Research Centre 

Corresponding Author: Alvira@aeirc-edu.com 

 

Abstract 

Aromatherapy is an ancient scent treatment that has gained a lot of attention in the contemporary research for its 

various benefits. The role of olfactory stimulation leading to neuropoeisis has been a major consideration for treating 

neurodegenerative disorders like dementia, Alzheimer’s and Parkinson’s as well as psychiatric symptoms like mood 

disturbances, anxiety and sleep problems. The literature review has concentrated on the significance of the olfaction 

in the mammalian physiology and enlightened the hypothesis with noteworthy evidences to support the idea that 

with more research and clinical trials aromatherapy can attest to be a major breakthrough in treating Alzheimer’s 

disease and reversing neurodegeneration. 

 

Keywords 

Aromatherapy, Neurpoeisis, Alzheimer’s, Dementia, Neuro-degeneration 

 

Aromatherapy 

Aromatherapy is one of the simplest and natural 

approaches used for healing. Literally, it is a 

derivative of two different words: aroma meaning 

fragrance, smell or scent and therapy meaning 

remedy, cure or treatment (University of Maryland 

Medical Center, 2013). It is a blend of biological and 

manipulative techniques that uses the fragrances or 

scented oils usually with massage, acupuncture or 

any other suitable treatment (British Columbia, 

2012). Thus, healing process involves the 

combination of two senses: touch and smell. The 

treatment is presumed to be helpful in supporting and 

balancing the mind, body and soul where each 

fragrance has a distinct effect on the nervous system 

and body. The practice involves the topical 

application, infusion in bath water, inhalation, and 

ingestion under strict supervision only. Yet, the 

manner of therapy is chosen according to the need of 

the consumer and requirement of the target. It is 

because each application has its own mode of action. 

For example, the inhalation of scents activates the 

limbic system while the topical application stimulates 

the thermal receptors of the dermis (Nordqvist, 2014 

and Demetriou 2000). 

 

Research in Aromatherapy 

Clinical studies have showed that fragrances 

treatment provides relaxation from anxiety, stress, 

depression, cancer related symptoms, agitation in 

dementia, pain and quality of sleep (Najafi, et al, 

2014, Williams, 2006, Holmes, et al, 2002, Ballard, 

et al, 2002, Fayazi, et al, 2011 and Diego, 1998). 

Aromatic therapy relieves both the mental and 

physical stress and has a tendency of enhancing the 

parasympathetic nervous system and autonomic 

nervous system (Liu, et al, 2014, Glass, et al, 2013 

and Chang K.M, et al, 2011). 

 

Senses; Smells and Behaviors 

Out of five senses, the aromatherapy engages two, 

touch and smell, for bringing upon the effects. These 

two senses are believed to have an emotional 

connection. For instance, the most sacred relationship 

of a Mother and her child bonds by these 

exceptionally strong senses (Demetriou, 2000). 

Studies show that babies tend to be finely sensitive 

towards the touch and scent of their biological 

mothers. These interactions bring physiological and 

psychological serenity to the babies and improve 

their growth and health (Agneta, 2014, Elizabeth et 

al, 2012, Delaunay-El, et al, 2010 and Doucet, et al, 

2007). Baby’s response to mother’s touch positively 

elevates when is accompanied with the odor (Durand 

K, 2013). 

 

The olfaction has an extraordinary significance in 

various physiological processes and psychological 

perceptions. For example, pheromones are the 

chemical substances secreted by the body of an 

animal that unlike all hormones, produce alterations 

in the physiology of other animals and not on one’s 

own body (Mostafaa, et al, 2012 and Tirindeli R, et 

al, 2009). Pheromones provide individuals with their 

characteristic odor which allows baby to identify 

their mother and a person to distinguish their partner 

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Alvira Ali 39 

  

Annals of Psychophysiology                                                                                                        Volume 3, October 2016                  
©Advance Educational Institute & Research Centre                                                                    www.aeirc-edu.com 

ISSN 2412 - 3188 
 

from others (Lundstorm, et al, 2013 and 2008 and 

Sobel N, et al, 2001). 

 

Mammals have a distinct region in their olfactory 

system that senses the odors from pheromones and 

recognize them. The region is known as Vomeronasal 

Organ (Ogura, et al, 2010 and Tirindeli, et al, 2009) 

or Jacobson’s Organ (Moran, et al, 1991), and is 

located in the nose (Brennan, et al, 2006). The 

neuronal cells of this organ synapses with the 

Amygdala and then Hypothalamus (Nordqvist, 2014). 

Olfaction of pheromones chiefly determines the 

physiology that fortifies the survival and is required 

for the determination of the sexual preferences, 

mating behavior, reproduction cycle, hormonal 

secretions, alertness, defensive nature, social 

behavior and territory mark (Woodley, et al, 2015; 

Dibattista, et al, 2012; Ogura, et al, 2010; Salazar, et 

al, 2009; Richard, et al, 2009; Snowdown, et al, 2006 

and McClintock, 1998). Even though scents have 

similar effects on humans but it only plays a small 

role. It is because homosapiens have more developed 

and complex nervous system and evaluate situations 

and preferences with higher level of cognition 

(Mostafaa, et al, 2012). 

 

Furthermore, pheromones have a very unusual 

function in some mammals like scientists have 

observed that when a pregnant mouse shares the 

vicinity with an unfamiliar male mouse, the 

pregnancy gets terminated naturally. This 

phenomenon is called the Bruce Effect and mainly 

involves the olfaction. The pregnant female senses 

the odor of a strange mouse, as the male secretes the 

pheromones. The scent influences the pregnancy in a 

way that it dampens the prolactin secretion in the 

female body. Prolactin is a precursor for progesterone 

and thus, the production of this hormone inhibits and 

as progesterone supports the gestation, the reduction 

causes the abortion. The nature is said to be adaptive 

because when new male animals take the dominancy, 

they do not father the unrelated baby, and rather they 

kill those newborns and mate with the females to give 

rise to their own bloodline. This adaptation saves the 

female from undergoing the stress of pregnancy and 

delivery, as the child would have no chances of living 

(Rajendren, et al, 1987, Yong, 2012 and Science 

Whiskers, 2012). 

 

Scents and Brain 

The sense of smell is found to be 10,000 times 

stronger than the other senses. A stimulus from 

sensing a fragrance travels more quickly towards the 

brain than others. It is estimated that our nose can 

sense 10,000 different scents distinctively (Nordqvist, 

2014 and Damian, 1995). The stimulus of an odor is 

taken from the nasal reception to brain, where it 

stimulates the Amygdala and Hippocampus (Jorge, et 

al, 2014) in the Limbic System (Halcon, 2013). If the 

functions of these brain areas are summarized then it 

can be stated that amygdala holds the responsibility 

of generating an appropriate behavioral response 

while hippocampus determines the behavioral 

patterns and stores the memories (Guyton, 2010). 

Primarily, the reward and punishment centers are 

located in this region while hypothalamus is also 

responsible for the regulation of arterial pressures, 

heart rate, body temperature, thirst, water 

reabsorption from kidneys, uterine contractility, milk 

ejection, hunger, feeding reflexes and hormonal 

secretion from the anterior pituitary (Guyton, 2010). 

Thus, the fragrances can cause the alterations in 

body’s physiological processes. The evidence of 

promising relationship between the hypothalamus, 

endocrine system and olfaction is the Kallmann 

Syndrome. 

 

Kallmann syndrome is an X-linked genetic disorder 

which is characterized by the lack of olfactory 

perception and a delay in puberty. The mutated gene 

causes anomaly in the migration of olfactory receptor 

cells and gonadotropin releasing cells that disturbs 

the hypothalamus-pituitary axis that ultimately delays 

the puberty. Thus any defect in the olfactory bulb 

interrupts the communication between the 

hypothalamus and anterior pituitary gland (Lutz, et 

al, 1993 and Rugarli, et al, 1993). 

It is also reported that scents have an ability to bring 

upon emotional changes in an individual depending 

on the consumer’s perception and memory. This is 

called the Proust Effect, where a scent can evoke 

certain memories (Chen, 2013, Campen, 2013 and 

Hamilton, 2012).  

 

Olfactory System 

Evolutionary studies have confirmed that olfactory 

system is the oldest system that perceives the 

sensations in the mammalian body and has an ability 

to regenerate (Purves, 2001). The Olfactory 

Ensheathing Cells or OECs in the olfactory bulb 

provides the fascicles for the repair and regrowth of 

the mature olfactory neuronal cells. Scientists have 

been successful in utilizing regenerative properties of 

these cells by implanting them into the sites of spinal 

damage and successfully treating the lower body 

paralysis (BBC News, 2014). 

The olfactory system has a prominence in all the 

sensory processes due to various reasons which may 

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Alvira Ali 40 

  

Annals of Psychophysiology                                                                                                        Volume 3, October 2016                  
©Advance Educational Institute & Research Centre                                                                    www.aeirc-edu.com 

ISSN 2412 - 3188 
 

include the sensitivity, association with memory and 

behavior, harmony with endocrine functions and a 

reputation of being the oldest. Nonetheless, amongst 

all these the one peculiar aspect is that the olfactory 

sensations reach the cerebral cortex directly (Li, et al, 

2007), without relaying information through the 

thalamus (Guyton, 2011). The electro-olfactogram 

further activates the nerves of the nervous system 

along the olfactory tract. The significance of 

olfactory nerve activation is its ability of potentiating 

the power of incoming stimulation. Hence, our nose 

holds a remarkable sensitivity even towards a small 

concentration of odor (Tortora, 2010). 

 
Figure: Stimulation of Olfactory Cells by the Odor 

and Activation of Electro-Olfactogram. (Adapted 

from Chen, et al, 2012, Guyton, 12th edition, Moran, 

2007, Knecht, et al, 2004, Scott, et al, 2002 and 

Furukawa, et al, 1989). 

 

Conclusion 

Aromatherapy has gain a lot of attention in 

contemporary research for treating neurodegenerative 

conditions like dementia and psychiatric symptoms 

like anxiety, sleep problems and mood disturbances 

(Perry, et al, 2006). Although the neurophysiological, 

biochemical and pharmacological basis of the 

aromatic treatments are not well-recorded yet 

researchers are still working dedicatedly on the 

clinical trials to establish a ground for the efficacy of 

the techniques involving the scent therapies. 

The aromatic treatment has been recently observed to 

have some influence on deteriorating cognitive 

functions and thus attained a status of interest in the 

domain of Alzheimer’s disease. Anosmia, the loss of 

sense of smell, is often developed along with 

dementia in the AD because of the gradual 

neurodegeneration and development of 

neurofibrillary tangles and plaques. Neuroscientists 

have stated the fact that neurons in the olfactory bulb 

can undergo regeneration throughout the life. With 

regard to this observation, it is hypothesized that the 

olfactory excitation provided by the aromatherapy 

can help in stimulating the neuropoiesis in the 

olfactory bulb. As olfactory region tends to be 

directly in communication with the hippocampus and 

limbic system, it is believed that the neuronal 

regeneration reaches these regions and initiates 

neuropoeisis that ultimately improves the cognition 

and prevents further deterioration and memory loss 

(Jimbo, et al, 2009). 

 

Working on these aspects with clinical trials and 

molecular studies can be a major breakthrough in 

treating Alzheimer’s disease and other 

neurodegenerative conditions like dementia and 

Parkinson’s. It is not though possible to utilize the 

benefits of aromatherapy without noting down the 

general effects and thus reliable evidence is required 

to include these therapies to the clinical practices. 

Therefore, thorough research is needed in future 

where these interventions can help with mental health 

issues and more studies involving physiological and 

biochemical analysis for learning the association 

between hormonal and neurotransmitters must also 

be performed. 

 

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Annals of Psychophysiology                                                                                                        Volume 3, October 2016                  
©Advance Educational Institute & Research Centre                                                                    www.aeirc-edu.com 

ISSN 2412 - 3188 
 

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ISSN 2412 - 3188 
 

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