Abstract This study aimed to evaluate the effect of frankincense essential oil inhalation on short-term memory (STM). The participants were 100 male students aged between 18-26 years. Before the experiment, measurements were taken for systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse rate (PR). Additionally, STM tests, such as memory of images, memory of numbers, and memory of words, were conducted. Participants were then rested in a treatment room that was scented with frankincense oil for 10 minutes. After that, the STM tests and physiological indicators were once again measured. DI water was utilized in place of frankincense oil in the control group. After frankincense oil inhalation, a significant decrease in SBP and improvements in STM test scores (P<0.05) compared to the control group were observed. Gas chromatography analysis demonstrated that frankincense oil is comprised of α-thujene, sabinene, α-pinene, and α-limonene, all of which have been shown to possess cognitive enhancing properties that are advantageous for brain function.

Keywords: Frankincense oil, Short-term memory, Aromatherapy, Male university student

Funding: The authors are grateful for the research funding provided by the Mae Fah Luang University, Chiang Rai, Thailand.

Citation:  Wuttisin, N., Nakornsri, P., and Pimsan, A. 2026. The effect of frankincense essential oil inhalation on short-term memory in Male University students. Natural and Life Sciences Communications. 25(1): e2026002.

INTRODUCTION

Short-term memory (STM) is the information that a person is currently thinking about or is aware of. It is also called primary or active memory. STM plays a vital role in the performance of a wide range of tasks such as decision-making and problem-solving (Baddeley and Hitch, 1974). Recent events and sensory data such as sounds are stored in STM. STM often encompasses events throughout for anywhere from 30 seconds to several days. STM needs to be recalled for a lesser amount of time than long-term memories; the brain's ability to store short-term items is more limited (Cowan, 2008; Nelson and Miller, 2020). STM ability is a common problem among university students and also has significant effects on physical and mental health. There are many causes of STM loss. Stress has a deteriorating effect on hippocampal function which has a major role in learning and memory. Various types of stress induce short-term memory impairment (Kim et al., 2013). Poor sleep quality is one of the causes of STM loss. Deficits in STM during sleep deprivation arise from decrements in basic attentional and perceptual processing as well as decrements in memory maintenance, while memory encoding and retrieval processes seem to be relatively spared (Tucker, 2013). Smoking is an additional cause of STM loss. Smoking impairs the blood supply to the brain and leads to memory lapses. Many studies have shown that smokers have a more rapid decline in brain function, including memory than non-smokers. Many components of cigarette smoke have been confirmed to be toxic to the human brain and cardiovascular system (Liu et al., 2013). Smokers have less striatal dopamine transporter availability, and dopamine transporter availability is correlated with cognitive function in healthy individuals (Chiu et al., 2011).

Numerous studies have found that aromatherapy affects the human brain and emotions. Many essential oils have been utilized for STM improvement including rosemary (Rosmarinus officinalis L.), bergamot (Citrus hystrix DC.), lemon balm (Melissa officinalis L.), ylang-ylang (Cananga odorata), lavender (Lavandula aangustifolia), ginger (Zingiber officinale Rosc.) and peppermint (Mentha piperita L.) (Ali et al., 2015). Inhalation of rosemary and lavender oils has been reported to increase the human short-term image and numerical memory (Filiptsova et al., 2018).

Frankincense (Boswellia Carterii) is the aromatic oleo gum resin obtained from the bark of various Boswellia species (Rameshkumar, 2014). Frankincense is the major medical incense. It was burned to give an aromatic smoke and provide an aroma smell (Jimbo et al., 2009). Frankincense oil has a fresh, balsamic, resinous, and green note, which is used in oriental bases, ambers, florals, colognes, and male fragrances. The major constituents of frankincense oil are monoterpenoids α-pinene, limonene, myrcene, and sesquiterpenoids (Rameshkumar, 2014). Ancient people have chewed frankincense oil to enhance emotion, memory, and physical well-being (Jimbo et al., 2009). However, there is no scientific information to approve the use of frankincense oil for STM improvement. Therefore, this study was designed to evaluate the efficiency of frankincense oil inhalation for STM improvement in male university students.

MATERIALS AND METHODS

Materials

Frankincense oil was purchased from Thai-China Flavors and Fragrances Industry Co., Ltd., Thailand. Frankincense oil was diluted with denatured ethanol 95% in a proportion of 1:10.

Determination of frankincense oil composition

Frankincense oil was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The essential oil was prepared by diluting it with n-hexane in a 1:10 ratio (v/v). GC-MS was performed on an Agilent 6890 Gas Chromatography with quadruple detector, on an HP-5MS capillary column (0.25 mm × 30 m; 0.25 µm film thickness). The carrier gas was helium with a flow of 1.0 ml/min, spitless mode. The injector and detector temperatures were maintained at 200 and 280°C, respectively. The column temperature was programmed at 60°C and then heated to 325°C with an increasing rate of 3°C/min. The MS operated at 70eV ionization energy and the ion source temperature was 230°C. The mass range was from m/z 30-300 amu (Liu et al., 2013).

Participants

The participants were 100 male students aged between 18-26 years who studied at Mae Fah Luang University, Chiang Rai, Thailand. Inclusion criteria included healthy participants without a history of an allergic reaction to essential oils and had Raven’s Standard Progressive Matrices (SPM) score at Grade II (above the average in intellectual capacity). This study was approved by the Ethics in Human Research Committee of Mae Fah Luang University (No.REH-19002). All participants received information about the study and signed an informed consent sheet.

Questionnaires

The raven’s standard progressive matrices test (SPM)

SPM test was used to determine the Intelligence Quotient (IQ) of the participant and used to classify the participant into five grades as follows; Grade I superior >94%, Grade II above the average 75-94%, Grade III average 25-74%, Grade IV below average 5-24% and Grade V defective <4% (Vass, 1992). SPM was used for participant screening. The participants who are in the same grading will be selected. After the screening, it was found that most participants were in grade II, then only grade II participants were recruited to participate in this study.

Short-term memory (STM) test

The present study employed the Short-term memory (STM) test, which consisted of assessing memory for images, numbers, and words (as delineated in Figure 1) to evaluate STM. For example, the participants had 20 seconds to memorize the images and were instructed to recall as many images as they could. After 20 seconds, the images were removed. The participants were required to replicate the images they had recalled in the same form within 60 seconds. The test results were assessed by the number of images correctly reproduced (Filiptsova et al., 2018).

Figure 1. Images, numbers, and words for short-term memory test.

Satisfaction after the experiment

The participants were requested to assess their level of satisfaction after the experiments by responding to a questionnaire. The questionnaire was divided into three parts. The first part was designed to collect the participants' satisfaction with product characteristics such as odor, preference, and attractiveness. The second part included feelings experienced after smelling, such as feeling refreshed, relaxed, active, calm, drowsy, and experiencing dizziness. The third part involved the participants' perception of their memory capabilities. The levels of participant satisfaction were evaluated using a five-point Likert scale as follows; excellent (4.21-5.00), very good (3.41-4.20), good (2.61-3.40), neutral (1.81-2.60) and bad (1.00-1.80).

Physical effect

Physiological data measurements were conducted before and after the experiments using the Omron Series HEM-7211 device. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse rate (PR) were measured at the upper right arm, aligned with the heart, while participants were in a seated position.

Treatment room

The treatment room was 3.85×6.50 square meters. All the windows were closed during the experiments and the temperature was controlled at 25°C. In the middle of the room, two 250 ml glass beakers with cotton wool were placed and 10 drops of frankincense oil were added to each beaker. The room was prepared 10 minutes before the arrival of participants which was enough for spreading the particles of the oil in the room and obtaining a character odor. The participants were not informed about the presence of the aroma of frankincense oil in the room. The control room was the same size as the treatment room but deionized water was used instead of frankincense oil.

Protocol of the study

One hundred participants with SPM grade II scores were divided into test and control groups, each comprising 50 participants. SBP, DBP, and PR were assessed before the experiment began. Participants were asked to self-assess their stress levels and complete a STM test. Following this, participants rested in a treatment room for 10 minutes. After an inhalation period, they repeated the STM test, and physiological indicators were measured again. The results were subsequently compared.

Statistic

All data are presented as the means and standard deviations. The Paired Sample T-test was employed to determine the significant difference in each group before and after the experiment. An Independent Sample Test was used to compare the different data between the two groups.

RESULTS

The GC-MS analysis

Figure 2 and Table 1 demonstrated the sample analyzed by GC-MS. It was found that frankincense essential oil was composed of α-thujene (57.18%), sabinene (7.58%), α-pinene (7.17%), anisole (6.16%), p-cimene (5.85%), δ-3-carene (4.76%) and α-limonene (3.42%).

Figure 2. Chemical constituents of frankincense oil determined by GC-MS.

Table 1. Chemical constituents of frankincense oil.

Demographic characteristics

The demographic characteristics of the participants were outlined in Table 2, indicating no significant differences in age and stress level between both groups (P>0.05). Additionally, the results revealed no significant differences in SBP, DBP, PR, and IQ scores. Moreover, there were no significant differences in the scores of STM tests between the two groups prior to the experiment.

Table 2. Demographic characteristics of participants.

Note: Values are given as mean ± S.D.

Physiological effects after the experiment

The SBP, DBP, and PR before and after frankincense oil inhalation were exhibited in Table 3. A significant decrease in SBP was observed after frankincense oil inhalation (P<0.05). However, the reductions in DBP and PR were not statistically significant.

Table 3. Physiological effects after frankincense oil inhalation.

Note: ^a(After-Before). The P-value indicated the difference between the data before and after the experiment. P<0.05 indicated a significant difference.

STM test after frankincense oil inhalation

The result of the STM test are summarized in Table 4. After frankincense oil inhalation, there was a significant improvement in STM test scores, particularly in image, number, and word recognition in the test group. In contrast, the control group showed a significant decline in their scores for image and number recognition.

Table 4. STM scores after frankincense oil inhalation.

Note: ^a(After-Before)

Satisfaction of participants after the experiment

The satisfaction of the participants after the experiment is exhibited in Table 5. The frankincense oil inhalation group reported experiencing a greater sense of refreshment, relaxation, and calm compared to the control group. Additionally, they perceived an enhancement in their memory capacity compared to the control group.

Table 5. Satisfaction of participants after the experiment.

DISCUSSION

The chemical composition of frankincense oil varies depending on the source plant. It was observed that inhalation of frankincense essential oil resulted in increased scores on STM tests for numbers, images, and words compared to baseline values. Frankincense oil contains α-thujene, sabinene, α-pinene, δ-3-carene and α-limonene (Al-Yasiry and Kiczorowska, 2016) which exhibit memory-enhancing properties (Kim et al., 2006). α-Thujene, a predominant monoterpene in frankincense oil, had not been directly investigated for memory enhancement; however, essential oils containing α-thujene, including juniper oil (Juniperus communis L.), yarrow oil (Achillea biebersteinii), and black cumin oil (Nigella sativa), demonstrated neuroprotective properties in experimental models of memory and learning impairment in rats (Cioanca et al., 2014; Akbaba et al., 2018; Silva-Correa et al., 2021). Sabinene was reported to possess antioxidant, anti-inflammatory, and neuroprotective properties. In particular, it has been shown to exert neuroprotective effects and to enhance memory performance in mice subjected to lipopolysaccharide-induced neuroinflammation, oxidative stress, and learning/memory impairment (Amenotie et al., 2025). α-Pinene was reported to exert beneficial effects on memory. Evidence from rodent models showed that it improved learning and memory performance, while also exhibiting antioxidant and anti-acetylcholinesterase activities, mechanisms that were commonly associated with cognitive enhancement (Goudarzi and Rafieirad, 2016). Finally, α-Limonene was recognized for its ability to reduce oxidative stress, ameliorate cognitive disorders, and prevent neuronal degeneration in mice (Sarika et al., 2017). Numerous studies have demonstrated that several compounds derived from frankincense oil may contribute to cognitive support through various neuroprotective mechanisms in animal models. To date, only one clinical study has reported that four weeks of frankincense consumption facilitated the acquisition and retention of motor memory in older men (Asadi et al., 2019). The present study represents the first investigation into the effects of frankincense oil inhalation on short-term memory enhancement in human subjects. Consequently, evaluating the efficacy and safety of these phytochemical compounds in short-term memory enhancement remains a promising area for future research.

Blood pressure and pulse rate serve as indicators of the autonomic nervous system's response to stress and are associated with physiological alterations. The decrease observed in SBP, DBP, and PR following frankincense oil inhalation indicates a reduction in alertness and an increase in states of calmness and relaxation (Seol et al., 2013). Frankincense essential oil contains α-limonene, which enhances vasorelaxation, thereby lowering heart rate and blood pressure (Santos et al., 2011). Additionally, α-pinene has been found to help reduce stress and anxiety (Hashemi and Ahmadi, 2023). Aromatherapy is a potentially relaxing and therapeutic remedy, proven to be especially helpful in alleviating stress and anxiety. It has been shown to lower heart and breathing rates, reduce blood pressure, and restore hormone balance (Seyyed-Rasooli, 2016). Therefore, frankincense oil may induce a decrease in alertness and increase feelings of calmness and relaxation.

CONCLUSION

Frankincense essential oil contains α-thujene, sabinene, α-pinene, and α-limonene. This study found that inhaling frankincense essential oil could help improve STM scores for numbers, images, and words in male students. Additionally, it was found to reduce SBP and induce feelings of refreshment, calmness, and relaxation.

ACKNOWLEDGEMENTS

The authors would like to thank the volunteers who participated in this study.

AUTHOR CONTRIBUTIONS

Panassaya Nakornsri and Aranya Pimsan conducting the experiments, performed the result analysis and wrote the manuscript. Narunan Wuttisin designed the experiments and wrote the manuscript. All authors have read and approved of the final manuscript.

CONFLICT OF INTEREST

The authors declare that they hold no competing interests.

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