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. 2024 Nov 20;9(11):715.
doi: 10.3390/biomimetics9110715.

Neurofeedback Technology Reduces Cortisol Levels in Bruxismitle Patients: Assessment of Cerebral Activity and Anxiolytic Effects of Origanum majorana Essential Oil

José Joaquín Merino  1 , José María Parmigiani-Izquierdo  2 , Adolfo Toledano Gasca  3 , María Eugenia Cabaña-Muñoz  2
Affiliations

Neurofeedback Technology Reduces Cortisol Levels in Bruxismitle Patients: Assessment of Cerebral Activity and Anxiolytic Effects of Origanum majorana Essential Oil

José Joaquín Merino et al. Biomimetics (Basel). .

Abstract

Cerebral activities were measured during 21 essions in NeurOptimal (NO)-trained patients with bruxism. Salivary cortisol levels were quantified for each six training sessions (session 1, 6, 12, 18, 21) in 12 patients with bruxism after performing their pre- and post-NeurOptimal sessions. Their cortisol levels were compared with controls (without stress). We evaluated whether NO overtraining could reduce stress in bruxism after 21 repeated sessions with/without Origanum majorana inhalation by using nasal impregned filters with this essential oil (n = 12). This study enrolled 89 participants (590 salivary samples for cortisol assessment by ELISA ng/mL). Salivary samples were collected at several NO learning sessions (session 1, 6, 12, 18, and 21). In the present study, we assessed whether Origanum majorana essential oil exposure during 21 NO training sessions can promote anxiolytic effects by reducing cortisol levels in Bruxismitle patients or modulate their brain activities. The experimental design also included control subjects without NO training (n = 30) and unstressed participants without bruxism, as well as trained NeurOptimal (n = 5) participants during the 21 sessions, also including control subjects without stress. In our study, NeurOptimal post-training decreased cortisol levels in Bruxismitle patients, reducing stress scores on the Hamilton II scale after 21 NO sessions; finally, Origanum majorana essential oil exposure during NO training could enhance anxiolytic effects of repeated NO in Bruxismitle patients. The parameter divergence as an index of cerebral activity evaluates the reached difference between cerebral activity at pre-learning (PRE) minus post-training (POST) values in Bruxismitle participants with/without Origanum majorana odor exposure during each NO training sessions. As a consequence of NO overtraining, these cerebral activities fluctuate reaching a calm state while anxious states are associated with high divergences. The reduction in divergences when they are close to zero by habituation means a final calm state is reached by NO overtraining, while higher divergences mean anxiogenic states. Collectively, Origanum majorana essential oil inhalation during NO training could decrease salivary cortisol levels after 21 NO training sessions in Bruxismitle.

Keywords: NeurOptimal/neurofeedback; aromatherapy (Origanum majorana essential oil); brain activity; brain stimulation; cortisol; neural plasticity; neuromodulation; nutritional supplementation; stress.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Chromatographic profile.
Figure 2
Figure 2
Effect of NeurOptimal training on cerebral activities at pre-learning and post-training during 21 sessions in Bruxismitle participants with Origanum majorana stimulation (n = 12, 252 measurements) as well as in Bruxismitle participants without exposure to this essential oil (n = 12, 252 measurements). PRE: Brain activities at pre-learning sessions in Bruxismitle patients (blue line). POST: Brain activities at post-training sessions in Bruxismitle patients (green line). PRE-AE: Brain activities in Bruxismitle participants at pre-learning exposed to Origanum majorana odor during NO training (black line). POST-AE: Brain activities in Bruxismitle participants exposed to Origanum majorana odor at post-training (red line).
Figure 3
Figure 3
Divergences in all participants. FPRE: Brain activities in Bruxismitle patients at pre-learning sessions (blue column, Figure 3). POST: Brain activities in Bruxismitle patients at post-training sessions (green column, Figure 3). PRE NF + AE: Brain activities in Bruxismitle participants exposed to Origanum majorana odor at pre-learning sessions (black column, Figure 3). POSTNF + AE: Brain activities in Bruxismitle participants exposed to Origanum majorana odor at post-training in (red column, Figure 3).
Figure 4
Figure 4
Mean cerebral activities at NeurOptimal training (PRE-TEST) in Bruxismitle patients with/without Origanum majorana odor exposure. PRE-NF (blue column): brain activities in Bruxismitle patients at 21 pre-learning sessions (PRE) without Origanum majorana inhalation. PRE-NF AE: Brain activities at 21 pre-learning (PRE) sessions in Bruxismitle patients with Origanum majorana exposure (red column, Figure 4). * p < 0.05 vs. session 1.
Figure 5
Figure 5
Divergences in all participants: brain activities after POST training without/with Origanum majorana odor stimulation during 21 NeurOptimal training sessions. POST-NF (blue column): Brain activities during 21 neurofeedback (NeurOptimal) sessions (PRE) in Bruxismitle patients without Origanum majorana exposure during 21 NO sessions. POST-NF AE: Brain activities at 21 pre-learning (PRE) sessions in Bruxismitle patients without Origanum majorana exposure during each NeurOptimal session (red column, Figure 4, p < 0.05 vs. session 1).
Figure 6
Figure 6
Example of divergences in a patient: representative brain activities at pre-/post-training (PRE and POST) in Bruxismitle participant.
Figure 7
Figure 7
Examples of low, moderate, and high divergences (DIV).
Figure 8
Figure 8
Examples of low, moderate, and high divergences (DIV).
Figure 9
Figure 9
Several brain activities (DIV) in Bruxismitle participant at pre- and post-training with/without Origanum majorana exposure during NO session. These color lines are representative of each NO session (total 21).
Figure 10
Figure 10
Negative divergence (DIV) in NeurOptimal training with/without Origanum majorana odor exposure during 21 NO sessions. DIV Total NF: brain activities (total divergence—positive and negative—in Bruxismitle patients after 21 NeurOptimal sessions exposed to Origanum majorana odor in each session (green line, Figure 10). DIV negative NF: negative brain activities in Bruxismitle participants with Origanum majorana odor exposure during 21 sessions (red line, Figure 10).
Figure 11
Figure 11
Origanum majorana odor reduces cerebral activities by repeated NeurOptimal overtraining in Bruxismitle participants as compared to Bruxismitle participants without exposure to this odor during each NO session. NF: Total brain divergences (positive and negative) were evaluated in Bruxismitle patients after 21 NeurOptimal sessions (blue color) with a significant decrements on cerebral activity at session 8 (S-8, see left panel). NF + AE: Brain divergences (total Divergence—positive and negative) in Bruxismitle patients expose to Origanum majorana essential oil exposure session 16 (S-16).
Figure 12
Figure 12
Reduced Hamilton scores after 21 NO post-training (POST) sessions in Bruxismitle patients as compare their pre-learning sessions (PRE).
Figure 13
Figure 13
Anxiolytic effects of Origanum majorana essential oil in Bruxismitle participants after 21 NeurOptimal sessions by decreasing salivary cortisol levels.
Figure 14
Figure 14
Mean salivary cortisol levels (ng/mL) in Bruxismitle participants with/without Origanum majorana exposure during 21 NO sessions (S-1 + S-6 + S-21 + S-16 + S-21).
Figure 15
Figure 15
Percentage of cortisol levels vs controls. PRE: Brain activities in Bruxismitle patients at pre-learning sessions (blue column). POST: Brain activities in Bruxismitle patients at post-training sessions (green column). PRE-AE: Brain activities in Bruxismitle participants during 21 NeurOptimal sessions at pre-learning session with Origanum majorana essential oil (purpura column, Figure 15). POST-AE: Brain activities in Bruxismitle participants exposed to Origanum majorana odor at post-training (red column).
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