FR3127387A1 - Olfactory test method and kit - Google Patents

Abstract

The invention relates to an olfactory test method comprising the following steps: - step 0: having a number n of different odors, each odor being available at several different concentrations; - step 1: make an individual smell an odor (N) having a predetermined concentration (i) and ask him if he perceives the odor in order to obtain an initial response; - step 2: acquire the first response (I) of the individual for the odor (N); - step 3.1: if the first answer (I) is negative, smell the same odor (N) at a higher concentration; - step 3.2: if the first answer (I) is positive, ask the individual to name the odor (N) in order to obtain a second answer (G), the naming of the odor (N) being done at starting from a choice among a group of propositions (identification), the group of propositions being composed of a so-called target response proposition and other so-called distractor propositions; - step 4: acquire the second response (G) of the individual for the smell (N); - step 4.1: if the second response (G) is correct, i.e. if it corresponds to the target response, move on to the next odor to be identified; - step 4.2: if the second answer (G) is incorrect, move on to a next odor to be identified and subsequently carry out a catch-up with the same odor (N) at a higher concentration in a subsequent step; - step 5: acquire the catch-up response (R). Figure for abstract: figure 1

Description

Olfactory test method and kit

The invention relates to the field of olfactory tests, in particular to identify possible olfactory disorders. The invention relates more particularly to an olfactory test method accompanied by a method for interpreting test results. The invention also relates to an olfactory test kit making it possible to implement the test method and the associated diagnosis.

An olfactory test can reveal a person's olfactory abilities. This can be interesting, for example, if you want to train or test a student wishing to practice the profession of "nose" to become a perfume designer. A test can also make it possible to verify that a person has their full olfactory capacities, or to identify an olfactory disorder that could interfere with the comfort of this person's life or reveal a pathology.

At the level of olfactory capacities, there may be on the one hand a peripheral impairment of olfaction, which is determined by an increase in the olfactory detection threshold of odors, so that a person may not perceive certain odors if they do not are not concentrated enough. On the other hand, there may be a central impairment, which resides in an alteration of the identification of odors, so that the person believes he smells a certain odor when it is another. At the early stage of an olfactory disorder, it may be this alteration of olfactory identification that is the most marked and specific.

The contribution of an olfactory test has already been demonstrated and its use has been recommended for several years. Are known tests such as the odor identification test marketed under the trademark "UPSIT", which evaluates the identification of odors, the test known under the name "ETOC" (European Test of Olfactory Capabilities) which is a self-test -administered with 16 odorants, or the test marketed under the “Sniffin'Sticks” brand, validated in several European countries. Nevertheless, in general, this is still very little used so far.

We already know in the state of the art, in particular according to document US6338715, a device and a method for identifying the minimum level of concentration that a person can perceive. To do this, this document proposes a digital olfactometer comprising a device for injecting droplets of fluid onto a heating element, via which the liquid is transformed into vapor to be felt by the user. During the test, if the user detects the odor at a concentration level, then the concentration is decreased and the test repeats; otherwise, the concentration level is increased until the threshold is determined. It should be noted that the evaluation as proposed in this document is focused solely on the concentration threshold at which the user is able to perceive the odorant. It is therefore a test to determine if the user is hyposmic or normosmic.

Another document EP3193712 describes an olfactometer capable of distributing several odors, using a computer system with the aim of detecting diseases. The computer system is designed to receive user inputs for various tests via a user interface. The system then calculates a score based on the tests performed and provides data indicating whether the user has a scent memory deficit.

Thus, the known tests of the state of the art do not make it possible to fully evaluate the olfactory capacities of a person, in particular both the peripheral capacities and the central capacities.

The aim of the invention is in particular to provide an olfactory test method allowing a better evaluation of the olfactory capacities of a person.

[Resumption of claims]

To this end, the subject of the invention is an olfactory test method comprising the following steps:
- step 0: having a number n of different odors, each odor being available at several different concentrations;
- step 1: making an individual smell an odor (N) having a predetermined concentration (i) and asking him if he perceives the odor in order to obtain a first response (I);
- step 2: acquiring the individual's first response (I) for the odor (N);
- step 3.1: if the first answer (I) is negative, smell the same odor (N) at a higher concentration;
- step 3.2: if the first answer (I) is positive, ask the individual to name the odor (N) in order to obtain a second answer (G), the naming of the odor (N) being done at starting from a choice among a group of propositions (identification), the group of propositions being composed of a proposition called the target response and other propositions called distractors;
- step 4: acquiring the second response (G) of the individual for the odor (N);
- step 4.1: if the second response (G) is correct, that is to say if it corresponds to the target response, moving on to a next odor to be identified;
- step 4.2: if the second answer (G) is incorrect, move on to a next odor to be identified and subsequently carry out a catch-up with the same odor (N) at a higher concentration in a subsequent step;
- step 5: acquire the catch-up response (R).

Thus, we propose a test in which, on the one hand, steps 1, 2 and 3.1 on the perception of odor make it possible to evaluate the olfactory capacities from the peripheral point of view, that is to say the threshold olfactory detection of an odor given by the person tested, especially when several odors are presented successively during the test. On the other hand, steps 3.2, 4 and 4.1 make it possible to evaluate the olfactory capacities from the central point of view, that is to say that we evaluate the capacities of identification of an odor. Finally, steps 4.2 and 5 make it possible to ensure that the identification capacities are independent of the concentration of the odor presented and to evaluate in a more reliable way the olfactory capacities from the central point of view.

Therefore, it is possible, with the present invention, to fully assess a person's olfactory abilities, and both peripheral and central abilities. This assessment is particularly interesting, for example, if you want to train or test a student wishing to practice the profession of "nose" to become a perfume designer. This assessment can also make it possible to verify that a person has their full olfactory abilities, or to identify an olfactory disorder that could interfere with the comfort of this person's life or reveal a pathology.

In particular, this evaluation can be particularly advantageous for evaluating olfactory disorders signs of the development of Alzheimer's disease (hereinafter "AD"). In fact, over the past twenty years, research has shown a very strong link between olfactory disorders and AD. Emphasis is placed on the early alteration of olfaction which acts as a harbinger of the disease since it is detectable in its asymptomatic phase. In addition, olfactory impairment is a precursor signal of the transformation of mild cognitive impairment into AD. Indeed, the first injured anatomical structures are located in the transentorhinal region of the temporal lobe and entorhinal in the initial phase, before progressing towards the limbic system, which marks the clinical appearance of the first signs of the disease.

In addition, at the early stage of an olfactory disorder, it may be the alteration of olfactory identification that is the most marked and specific, in particular compared to other pathologies, such as Parkinson's disease.

Thus, recent studies have shown that an olfactory identification test was comparable in predictive accuracy to neuroimaging and cerebrospinal fluid sampling.

Furthermore, the proposed method can also make it possible to identify and evaluate an olfactory disorder such as those appearing with the SARS-CoV-2 virus (responsible for COVID-19), or even to evaluate and possibly quantify the recovery of the smell following COVID-19.

We understand that catching up allows the individual to smell the same smell again.

It is also understood that the steps listed above are steps that follow one another. Other steps may possibly be present between the listed steps.

According to other optional characteristics of the olfactory test method taken alone or in combination:

- Distractors include olfactory semantic distractors.

Thus, semantic distractors are presented, which can for example take the form of images and/or words; and olfactory, representing odors, other than that of the target response. This can later help to assess whether the person is mistaken and how much difficulty the person has in identifying odors. Indeed, the person tested can be offered different odors, making it possible to assess whether the person is mistaken about odors close or far from the one expected. This improves the quality and accuracy of the test performed.

It should be noted that certain diseases, such as Alzheimer's disease or COVID -19, cause damage to semantic networks. This is present in the form of an identification disorder at the central level, which prevents the person from distinguishing close odors. The use of olfactory semantic distractors allows a central perspective assessment of smell and semantic memory of odorants.

Especially with regard to COVID: olfactory disorders are centrally identified in the SARS-CoV-2 virus (responsible for COVID-19). According to various authors, there are olfaction and taste disorders in 15%-85% of patients. The test method proposed by the invention thus makes it possible to detect a central impairment sequel to the SARS-CoV-2 infection, resulting in a semantic impairment at the olfactory level on the distinctive features and approaching the impairments observed in a disorder central neurological at the internal temporal level.

- The group of olfactory semantic distractors proposed includes a predefined distractor as close to the target response and a predefined distractor as distant from the target response. For example, if the target response is clementine, orange can be predefined as the near semantic distractor and walnut as the far semantic distractor.

Thus, we can deduce that the person confusing the odor smelled with an odor close to the target response will be judged as having better olfactory capacities than the person confusing the odor with a distant odor.

The notion of close semantic distractor is particularly interesting in the context of central brain damage at the entorhinal level and affecting the semantic memory of odorants. In fact, when there is an early (or slight) impairment of the olfactory semantic memory, it is the close distractors that are affected. It should be emphasized that this particularity is crucial in the event of an early attack at the internal temporal level. By proposing a test to assess whether the person is mistaken about the close or distant distractors, and depending on the number of semantically close errors and the number of semantically distant errors, we can determine whether it is more or less severe damage.

The choice and grouping of near and far distractors is based on experience. In general, an odor qualified as a near distractor has more common distinctive features with respect to the target odor than a far distractor.

- Catch-up with the same odor (N) is done at the maximum available concentration.

This makes it possible to quickly check whether the identification disorders are independent of the concentration of the odor presented. Dispensing intermediate concentrations shortens the duration of the test process.

- When catching up with the same odor (N), the distractors are different from those in step 3.2 in order to avoid a deduction bias.

- Smell catch-up (N) is performed once all available odors have been presented to the individual with the aim of minimizing the repetition effect.

- The proposals are presented in the form of an image.

The fact of proposing images for the identification of the smell makes it possible to avoid that the presence of “a lack of the word” or a “lack of vocabulary” does not bias the calculation of the scores. This also makes it possible to avoid a test of words that is too long, and therefore in particular a problem of a test battery that is too long.

We note in particular that the "lack of the word" is a major symptom in Alzheimer's disease, but also in a large number of other pathologies (mood disorders, head trauma, neuromuscular diseases, etc.). The proposed test therefore makes it possible to better assess olfactory abilities and not to confuse them with other abilities.

- Steps 1 to 5 are repeated n times to present at least once all the odors available to the individual.

– The test method includes a step (step 6) of calculating a threshold score using the first responses (I) for each odor presented.

The threshold score assesses the individual's ability to perceive an odor. This allows in particular to know if the individual is hyposmic or normosmic.

Note that the threshold score corresponds to the average intensity at which the individual's first response I is correct.

– The method includes a step (step 7) of calculating an identification score, using the second responses (G) and the remedial responses (R) of each odor presented.

The identification score makes it possible to detect in particular a possible central attack. For example, if the cut-off score is within the norms and the identification score below the norms, central enthorinal involvement could be assumed. If both thresholds are lower than the norms, a more global central involvement (enthorinal and orbitofrontal) could be inferred.

Note that the identification score corresponds to the number of odors correctly identified.

– The method includes a step (step 8) of calculating a composite score using the first responses (I), the second responses (G) and the catch-up responses (R) of each odor presented.

The composite score provides an overall assessment of the individual's olfactory performance. Indeed, if the composite score is lower than the norms, it can be deduced that the person does not have sufficient olfactory capacities. In particular, it is possible to obtain an identification of a marker of Alzheimer's pathology at the early stage.

For example, points are awarded for each correctly recognized odor, giving more points the lower the concentration. If the individual does not smell the odor or gets the answer wrong, no points are awarded.

- Steps 2, 4, 5, 6, 7 and 8 are implemented by an electronic device.

The acquisition of answers as well as the calculation of different scores are computerized. This allows a simplified use of the test method and a faster score calculation. As the scores are directly available at the end of the test, it is possible to directly interpret the scores in terms of pathologies.

For example, this computerized version can be developed as a web application accessible via the Internet, so that it can be used on a computer or touch pad. Use on a touch pad or mobile phone makes the test easy to transport and administer. The course of the test, the recording of the answers and the calculation of the score are automatic, which allows the clinician to concentrate on the other aspects, such as the good understanding of the patient and the management of the different odorants. The app can be used without internet access. The first screen of the application allows you to enter, if desired, the name of the subject and of the person administering the test, for example a clinician.

The invention also aims to provide an olfactory test kit for implementing the test method, the kit comprising:
- odorous samples emanating from a plurality of different odors, each odor being available at several different concentrations;
- a means of storage and transport (case) configured to contain the odorous samples;
- a portable electronic device (tablet, telephone) for implementing the test method according to any one of the preceding claims, the device comprising a user interface.

The kit, which is transportable, makes it easier to use in the context of routine care.

Preferably, the means of storage and transport is capable of being hermetically closed.

Advantageously, the odorous samples are identified by a code allowing the portable electronic device to indicate which odor must be smelled by the individual.

The coding by letters of the alphabet makes it possible not to influence the participant. Preferably, the letter of the alphabet is unrelated to the corresponding smell.

Brief description of figures

The invention will be better understood on reading the following description given solely by way of example and made with reference to the appended drawings in which:
is an operating diagram of the test method according to one embodiment of the invention;
is an example of display during an odor identification step of the test method;

Claims (14)

Olfactory test method comprising the following steps:
- step 0: having a number n of different odors, each odor being available at several different concentrations;
- step 1: making an individual smell an odor (N) having a predetermined concentration (i) and asking him if he perceives the odor in order to obtain a first response (I);
- step 2: acquiring the individual's first response (I) for the odor (N);
- step 3.1: if the first answer (I) is negative, smell the same odor (N) at a higher concentration;
- step 3.2: if the first answer (I) is positive, ask the individual to name the odor (N) in order to obtain a second answer (G), the naming of the odor (N) being done at starting from a choice among a group of propositions (identification), the group of propositions being composed of a so-called target response proposition and other so-called distractor propositions;
- step 4: acquiring the second response (G) of the individual for the odor (N);
- step 4.1: if the second response (G) is correct, that is to say if it corresponds to the target response, moving on to a next odor to be identified;
- step 4.2: if the second answer (G) is incorrect, move on to a next odor to be identified and subsequently carry out a catch-up with the same odor (N) at a higher concentration in a subsequent step;
- step 5: acquire the catch-up response (R). A method according to claim 1 wherein the distractors comprise olfactory semantic distractors. Method according to claim 2, in which the group of olfactory semantic distractors proposed comprises a distractor predefined as close to the target response and a distractor predefined as distant from the target response. A method according to any preceding claim, wherein the make-up with the same odor (N) is at the maximum concentration available. A method according to any preceding claim, wherein when catching up with the same odor (N), the distractors are different from those in step 3.2. A method according to any preceding claim, wherein the odor remediation (N) is performed after all available odors have been presented to the individual. A method according to any preceding claim, wherein the propositions are presented in image form. A method according to any preceding claim, wherein steps 1 to 5 are repeated n times to present all available odors to the individual at least once. Method according to any one of the preceding claims, comprising a step (step 6) of calculating a threshold score (S _S ) using the first responses (I) for each odor presented. Method according to any one of the preceding claims, comprising a step (step 7) of calculating an identification score (S _I ), using the second responses (G) and the catch-up responses (R) of each odor presented. Method according to any one of the preceding claims, comprising a step (step 8) of calculating a composite score (S _M ) using the first answers (I), the second answers (G) and the catch-up answers (R ) of each odor presented. A method according to any preceding claim wherein steps 2, 4, 5, 6, 7 and 8 are implemented by an electronic device. Olfactory test kit including:
- odorous samples emanating from a plurality of different odors, each odor being available at several different concentrations;
- a means of storage and transport (case) configured to contain the odorous samples;
- a portable electronic device (tablet, telephone) for implementing the test method according to any one of the preceding claims, the device comprising a user interface. Olfactory test kit according to the preceding claim, in which the odorous samples are identified by a code allowing the portable electronic device to indicate which odor must be smelled by the individual.