Neuroscent aims to analyze EEG signals induced by olfactory stimuli in individuals with normal and impaired olfactory functions, with a focus on patients with tinnitus. The study seeks to develop reliable diagnostic methods using EEG to differentiate between normosmic and hyposmic subjects during olfactory tests, potentially enhancing our understanding of the brain's response to olfactory stimuli. This 24-month interventional study with a device to be patented will involve 1000 participants and aims to establish more effective diagnostic and therapeutic tools for olfactory disorders
The Neuroscent project investigates the EEG signals elicited by olfactory stimuli in both normosmic individuals and those with olfactory disorders, with a focus on tinnitus patients. The primary objective is to utilize EEG analysis to identify and quantify brain wave responses during olfactory tests with Sniffin' Sticks, aiming to accurately differentiate between normosmic and hyposmic subjects. This research aims to enhance the diagnostic precision and understanding of the interplay between olfactory and auditory stimuli in the brain. The 24-month, interventional study with a device to be patented, co-financed by the Ministry of Health and Ministry of the Interior under the PNRR 2023, will recruit 1000 participants divided into four groups: normosmics (550), hyposmics (150), tinnitus patients with hyposmia (150), and tinnitus patients without hyposmia (150). Participants will undergo comprehensive olfactory assessments, including the Sniffin' Sticks test, and EEG recordings will be taken during olfactory stimulation to capture brain wave patterns. Advanced data analysis techniques, such as Random Forest algorithms and t-SNE dimensionality reduction, will be employed to classify and interpret the EEG signals, aiming to develop effective diagnostic and therapeutic tools for olfactory disorders, thereby improving clinical outcomes and quality of life for affected individuals.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
1,000
The Sniffin' Sticks test, a validated method to evaluate olfactory functions, utilizes pen-like devices to dispense scents for testing identification, discrimination, and detection of odors. In this study, participants' responses to various scents are recorded. EEG (Electroencephalography) captures electrical activity in the brain during exposure to these odors by using an EEG cap fitted with electrodes on the scalp. This allows for the monitoring of brain wave patterns in response to olfactory stimuli. Both the Sniffin' Sticks test and EEG recordings are conducted simultaneously, providing a dual assessment of behavioral reactions and brain activity to odors. The goal of the study is to compare brain wave patterns and olfactory function in normosmic (normal smell), hyposmic (reduced smell), and tinnitus patients with and without olfactory impairments, delivering comprehensive insights into the neural basis of olfactory perception.
Enrollment and data collection
During this period, 1000 participants \> 18 y/o will be recruited and divided into four distinct groups: normosmics (550), hyposmics (150), tinnitus patients with hyposmia (150), and tinnitus patients without hyposmia (150). The primary outcome of the Neuroscent project is to assess the ability of EEG analysis to distinguish between normosmic and hyposmic participants during olfactory stimulation using the Sniffin' Sticks test.
Time frame: 22 months
EEG Parameters (in µV²)
Alpha Power: Measured in microvolts squared (µV²), representing the magnitude of Alpha wave activity during olfactory stimulation. Theta Power: Measured in microvolts squared (µV²), representing the magnitude of Theta wave activity during olfactory stimulation. We will make use of the Fourier transform as well, which is inherently dimensionless. The data acquisition setup involves placing blindfolded participants in an isolated room and administering three randomized olfactory stimuli (pure olfactory, trigeminal, and olfactory-gustatory) while collecting EEG data. Sessions start and end with a 30-second resting state.
Time frame: 22 months
Behavioral/Performance Measures (Scores)
Olfactory Threshold Scores (as per routinary diagnosis of olfactory performances): Derived from the Sniffin' Sticks test, these scores quantify participants' ability to detect odors, classifying them as normosmic or hyposmic. All the participants will undergo a complete olfactory assessment through the Sniffin' Sticks test. These are represented as numerical scores. The maximum score obtainable in the full Sniffin' Sticks test, which includes the three sub-tests (Threshold, Discrimination, Identification - TDI), is 48. This maximum score is achieved by summing the highest possible score from each of the three components: 16 for olfactory threshold (Threshold), 16 for olfactory discrimination (Discrimination), and 16 for olfactory identification (Identification).
Time frame: 22 months
Model Performance Metrics (Accuracy)
Random Forest Model Classification Accuracy: The accuracy of the classification model used to distinguish between normosmic and hyposmic participants based on EEG data, usually expressed as a percentage or a value between 0 and 1.
Time frame: 22 months
Dimensionality Change Outputs (t-SNE)
t-SNE Features: Although these don't have a specific unit, they represent the reduced dimensional data points used as features in the Random Forest model. These are typically dimensionless and used in the context of visualizing and improving model performance.
Time frame: 22 months
Pure Tone Audiometry Test
Pure Tone Audiometry (PTA), as per routinary diagnosis of Tinnitus: Measures hearing thresholds across frequencies, reported in decibels Hearing Level (dB HL) to determine the degree of hearing loss. The results are plotted on an audiogram, which shows the person's hearing threshold at different frequencies; a normal audiogram threshold is 0-20 dB HL between 250 and 8k Hz.
Time frame: 22 months (Simultaneously with the primary outcome)
Behavioral/Performance Measures (Scores)
Tinnitus Handicap Inventory (THI): Scores the impact of tinnitus on a scale from 0 to 100, where a higher score indicates a worse impact of tinnitus.
Time frame: 22 months (Simultaneously with the primary outcome)
EEG Parameters
EEG Data: Analyzed during exposure to olfactory stimuli (as per Primary Outcome), with features reduced via t-SNE and classified using a Random Forest algorithm.
Time frame: 22 months (Simultaneously with the primary outcome)
Model Performance Metrics
Random Forest Model Classification Accuracy: Measures the accuracy of the model used to classify participants across the four groups. This is typically expressed as a percentage or a value between 0 and 1. Fleiss' Kappa Statistic: Used to evaluate the agreement of classification, reported as a kappa coefficient.
Time frame: 22 months (Simultaneously with the primary outcome)
Power Analysis and Post-hoc Analyses
Power Analysis: Ensures the sample size is adequate to detect significant effects. This is typically expressed in terms of statistical power (e.g., 0.8 or 80%). Post-hoc Analyses: Conducted if significant differences are found, usually involving p-values or effect sizes.
Time frame: 22 months (Simultaneously with the primary outcome)
Auditory Brainstem Response (ABR)
Auditory Brainstem Response (ABR) as per routinary diagnosis of Tinnitus: Assesses the auditory nerve and brainstem's response to sound stimuli by measuring electrical activity in the brain. Results are typically presented as waveforms, with particular focus on latency and amplitude of specific waves, measured in milliseconds (ms) and microvolts (µV) respectively, to evaluate neural pathways involved in hearing.
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Time frame: 22 months (Simultaneously with the primary outcome)
Tympanometry
Tympanometry, as per routinary diagnosis of Tinnitus: Evaluates middle ear function by measuring tympanic membrane mobility, with results reported in decapascals (daPa) and milliliters (mL). The pressure reading in tympanometry reflects the air pressure in the middle ear cavity. A normal tympanogram shows peak compliance when the pressure in the ear canal matches the pressure in the middle ear, indicating normal middle ear function. The two units of measurement, pressure and compliance, are plotted on a two-dimensional graph. Pressure (daPa) is plotted on the x-axis and compliance, measured in mL, is plotted on the y-axis in the two-dimensional graph
Time frame: 22 months (Simultaneously with the primary outcome)