RU2775130C1 - Method for assessing the risk of suicidal behavior in terms of electrodermal activity - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely psychiatry, and can be used to assess the risk of suicidal behavior in terms of electrodermal activity. Stimulating effects are applied by electric current to the skin. Responses of the electrodermal activity are then recorded and evaluated. A series of 10 stimulating effects with an electric current is used, applied to the skin on the palm or to the fingers, the interval between which is 40 ± 15 s. Exosomatic registration of skin conductivity is carried out. When registering responses of electrodermal activity, reactive phasic changes in electrodermal activity (EDA) are isolated and the amplitudes A_n of reactive galvanic skin reactions (GSR) are determined. If after the n-th stimulus, at n=1-3, the next three do not cause reactive GSR, then the risk of suicidal behavior is assessed as high. If after the n-th stimulus, at n=4-7, the next three do not cause reactive GSR, then the risk of suicidal behavior is assessed as moderate. If a reactive GSR occurs in response to the nth stimulus in at least 8 cases out of 10, then the attenuation coefficient k, determined by the least squares method, is calculated from the values ​​of the amplitudes An of the reactive GSR. At the same time, the risk of suicidal behavior is assessed as high at k ≥ 0.5108, moderate - at 0.5108 > k ≥ 0.2231, low - at 0.2231 > k ≥ 0.05.

EFFECT: method provides a reduction in the subjectivity of the assessment, simplification of the diagnostic procedure due to the stated criteria for determining the risk in terms of electrodermal activity.

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Description

The invention relates to medicine, namely psychiatry and medical technology, and is intended to assess the risk and prevention of suicidal behavior in humans. The method is based on the assessment of the dynamics of the phasic component of the electro-dermal activity (or the sequence of the amplitude of the galvanic skin responses).

The term "electrodermal activity" (hereinafter - EDA) refers to the electrical properties of the skin. EDA is determined by the tone of the sympathetic division of the autonomic nervous system, which regulates perspiration through the skin. EDA reflects the level of vegetative activity and, indirectly, the psycho-emotional state of a person and the orienting reaction. Changes of short duration (several seconds) in EDA indicators determine the phasic component of EDA, also known as the galvanic skin response (GSR). EDA phasic changes occur spontaneously or in response to various stimuli (for example, a deep breath, a sharp, sudden sound, an emotionally significant semantic stimulus). EDA indicators change in disorders of the emotional sphere and are used to diagnose depression. EDA is a reliable, highly sensitive and specific marker of suicidal tendencies in depressed patients. It is known from the specialized literature that in patients with depression, either “addiction” can be observed, when the amplitude of the phasic EDA for each subsequent stimulus decreases, up to the complete disappearance of the reaction; or “hyporeactivity”, when the absence of phasic changes in EDA parameters in response to a stimulus is observed already after the 1st – 3rd stimulus. A graphical expression of habituation and hyporeactivity is shown in FIG. 1 and FIG. 2.

A known method is described in patent RU 2366359 C1 "Method for assessing suicidal risk in patients with depressive disorders". The method is implemented by comparing two coefficients of average coherence in the range from 0 to 30 Hz between the anterior-temporal-frontal and anterior-temporal-middle-temporal cortical zones of the right hemisphere of the background (EEG 1) and repeated electroencephalography performed against the background of the presentation of geometric shapes to the subjects (EEG 2). With negative values of the difference between the average coherence coefficients of EEG 2 and EEG 1, an increased suicidal risk is estimated.

The disadvantage of this method is that its implementation requires electroencephalography, a cumbersome method with a complex and non-obvious system of data interpretation, and the involvement of additional test material. In addition, the disadvantage of this method is the low accuracy of the criterion that determines only 2 gradations of the state of the person being examined: "yes" or "no" high suicidal risk.

The closest analogue of the proposed method is the method presented in the patent application (Application Number 15024908, WO2015/047147, US2016/0213297 publication date - 07/28/2016) "A Device for use in the evaluation of suicide risk".

The device contains a measuring unit with a sensor for measuring EDA on the patient's fingers. In addition to the portable measuring unit, the device also contains headphones and a computer for analyzing the measurements. The measuring unit is configured to give a sound signal to a person and receive a signal for EDA analysis from a person.

The operation of the device is as follows. The measuring unit transmits a well-defined specific sound stimulus to the patient through the headphones. Characteristics of the sound signal-stimulus: frequency - 1 kHz, intensity (loudness) - 90 dB, duration - 1 second, rise and fall time - 10 ms. The stimulus is repeated at an interval of approximately 40 seconds. The patient's EDA is recorded on the person's fingers and measured throughout the entire test, which takes 15 minutes. The measurement is performed at a constant voltage of 0.5 V on electrodes powered by a portable battery placed inside the measuring unit.

The disadvantage of this method is its low accuracy and roughness of the assessment, which determines only 2 gradations of the state of the person being examined: "yes" or "no", high suicidal risk. In addition, the method does not contain a quantitative criterion for classifying the examined person as a group of high suicidal risk.

The disadvantages inherent in known methods are eliminated in the proposed method by introducing three groups for assessing suicidal risk through the use of quantitative criteria, as well as the use of a stimulus not of auditory and visual, but of somatosensory modality.

The technical problem of the claimed invention is to create a method for assessing suicidal risk in persons with a depressive state in terms of GSR dynamics, taking into account both the “addiction” variant and the “hyporeactivity” variant.

EFFECT: technical result consists in providing an opportunity to formalize the procedure for diagnosing suicidal risk and, thereby, significantly: a) reduce the subjectivity of the assessment, b) simplify the diagnostic procedure, c) increase its reliability and safety, d) reduce the time of the test.

The specified technical result is achieved in a method for assessing the risk of suicidal behavior in terms of electrodermal activity, including the supply of stimulating effects with an electric current applied to the skin, recording and evaluating the responses of the electrodermal activity, using a series of n of 10 stimulating effects with an electric current applied to the skin on the palm or to fingers, the interval between which is 40 ± 15 seconds, exosomatic registration of skin conductivity is carried out, when registering responses of electrodermal activity, reactive phasic changes in electrodermal activity (EDA) are isolated and the amplitudes A _n of reactive galvanic skin reactions (GSR) are determined, while, if after n-th stimulus, at n=1-3, the next three do not cause reactive GSR, then the risk of suicidal behavior is assessed as high, if after the n-th stimulus, at n=4-7, the next three do not cause reactive GSR, then risk of suicidal behavior i is assessed as moderate, and if the reactive GSR occurs in response to a stimulating effect in at least 8 cases out of 10, then the attenuation coefficient k is calculated from the values of the amplitudes A _n of the reactive GSR, determined by the least squares method:

and the risk of suicidal behavior is assessed as high at k ≥ 0.5108, moderate at 0.5108 > k ≥ 0.2231, low at 0.2231 > k ≥ 0.05.

For stimulation, exposure to a single impulse of electric current with a duration of 10-20 ms, or exposure to a packet of rectangular pulses is used: the duration of an individual pulse in a pulse packet is 10-20 ms, the repetition period is 20-50 ms, the packet duration is 30-1000 ms, the current amplitude pulses - 50-500 μA, current density not higher than 500 μA / cm ² .

Exosomatic recording of the skin conductivity is carried out in the range from 0.1 to 100 μS with a sampling rate from 5 to 20 Hz.

The phasic component of skin conductance includes an increase in skin conductance for more than 0.3 sec, which occurred in the interval of 0.2-3 sec after the stimulus, and with an amplitude of more than 0.02 µS.

The claimed invention is illustrated on graphic materials, where:

In FIG. 1 – Dynamics of the phasic component of EDA of the hyporeactive type

In FIG. 2 - Dynamics of the phasic component of EDA of the habituation type

In FIG. 3 - Schematic diagram of the interaction of modules of the hardware-software complex for diagnosing the risk of human suicidal behavior.

In the proposed method, quantitative indicators of GSR dynamics are correlated with three degrees of risk of suicidal behavior: high, moderate, low.

The method is implemented using a hardware-software system consisting of three modules: a control module (personal computer), an EDA registration module and a stimulation module. The scheme of interaction between the system modules is shown in Fig. 3.

The EDA registration module is designed for exosomatic (by Feret) registration of the conductivity (resistance) of the skin on the palm or from the fingers in the range from 0.1 to 100 µS (10 kΩ to 10 MΩ) with a sampling frequency of 5 to 20 Hz. The module includes two electrodes fixed on the skin of the palm or the inner part of the phalanges of the fingers. The voltage between the electrodes is not more than 3 V, the voltage value is determined by the current resistance of the skin at the place where the electrodes are applied. The direct current flowing between the electrodes during the measurement process does not exceed 10 µA, the direct current density is not more than 10 µA/cm2 ^.

Data from the EDA registration module are sent to the control module (personal computer) for storage, visualization and further analysis.

The stimulation module performs a stimulating effect with electric current pulses used to evoke the EDA change reaction - the galvanic skin response (GSR). The stimulation module includes two electrodes for delivering electrical stimuli to the skin. The control of the supply of the stimulating effect by the stimulation module is carried out by the control module (personal computer).

The stimulating effect is carried out by a single rectangular pulse or a packet of rectangular pulses.

The pulse duration when exposed to a single pulse is 10-20 ms.

The duration of an individual pulse in a burst is 10–20 ms, the repetition period is 20–50 ms, and the burst duration is 30–1000 ms.

The pulse current amplitude is 50-500 µA, the current density is not higher than 500 µA/cm2 ^.

Modules for registration of EDA and stimulation can be made as separate devices, or made as a single monoblock. In the latter case, it is allowed to use the same electrodes for registration of EDA and for the implementation of a stimulating effect.

The method includes three sequential procedures (blocks):

1. Registration of EDA on the palm or on the phalanges of the fingers in response to a series of electrical stimuli - measuring unit . It is performed using the EDA registration module and the stimulation module. EDA data and stimulus delivery time are displayed on the computer screen and stored for further analysis.

2. Identification of the phasic components of EDA and determination of the amplitude of the galvanic skin response (GSR) - calculation unit (computer) . It is carried out on a personal computer using a specialized program automatically or manually.

3. Analysis of the dynamics of changes in GSR amplitudes and assignment of the result to one of the three risk groups for suicidal behavior in accordance with the established numerical values - qualifying block . Runs on a personal computer.

1. The measuring unit implements a series of 10 stimulating effects with parallel registration of the conductivity (resistance) of the skin on the palm or from the fingertips.

The interval between stimulating effects in a series is 40±15 seconds and is controlled by a normal distribution.

The characteristics of the stimulating effect (amplitude, single pulse or burst of pulses, duration, number and repetition period of pulses in the burst) are set by the operator before testing for each subject.

2. The calculation block of the proposed method implements the following functions:

2.1. Isolation of reactive phasic EDA changes (reactive GSR), according to the following criterion: reactive GSR is considered to be an increase in skin conductivity for more than 0.3 sec, with an amplitude of at least 0.02 µS, and occurring in the interval of 0.2-3 sec after the stimulating effect;

2.2. Determination of the amplitudes of reactive GSR A _n corresponding to the n-th stimulating effect , n = 1…10, in case GSR are detected;

3 . The qualifying block implements the function of assigning the subject to one of the three risk groups for suicidal behavior ( low , moderate and high ) according to the following algorithm:

3.1. The type of response is determined: hyporeactive type, if after the n-th (n = 1 ... 7) stimulating effect, three subsequent ones with numbers n + 1, n + 2, n + 3 do not cause reactive GSR (according to criterion 2.1), or addiction - in the event that reactive GSR occurs in response to a stimulating effect in at least 8 cases out of 10.

For a case that does not fall under the definition of hyporeactive type or habituation, it is not possible to draw a correct conclusion, and additional research is recommended.

3.2 To respond by the type of habituation for a range of values An ( _n = 1…10) , the attenuation coefficient k is calculated, determined by the least squares method (LSM) on the assumption that the empirical values of the amplitude of the reactive GSR A _n obey the law:

A _n = Ae ^–k⋅n + ν _n , (1),

where n = 1…10 is the number of the stimulating effect, e is the base of the natural logarithm (Euler number), ν _n are random variables with zero mathematical expectation.

The value of k is determined by the formula:

(2)

(2)

In the absence of a reactive GSR (according to the criterion of paragraph 2.1) on the nth stimulating effect, the value of the amplitude A _n in formula (2) is taken equal to 0.01 μS (due to the inapplicability of the values A _n = 0 in calculations).

3.3. The assignment of the subject to the corresponding risk group is carried out according to table 1:

Table 1. Quantitative indicators (criteria) of risk groups for suicidal behavior.

addictive hyporeactivity risk group k ≥ 0.5108 n = 1…3 high 0.5108 > k ≥ 0.2231 n = 4…7 moderate 0.2231 > k ≥ 0.05 short

The method is implemented as follows .

Electrodes are placed on the palm or phalanges of the subject's fingers (Fig. 3). A series of 10 stimuli is delivered from the stimulation module.

In parallel, the conductivity (resistance) of the skin on the palm or from the fingers is registered. The interval between stimulating effects is 40±15 seconds.

The characteristics of the stimulating effect (amplitude, single pulse or burst of pulses, duration, number and repetition period of pulses in the burst) are set by the operator before testing for each subject.

Throughout the series, the amplitudes of reactive GSR A _n corresponding to the nth stimulus are also recorded (reactive GSR is considered to be an increase in skin conductivity for more than 0.3 sec, with an amplitude of at least 0.02 µS, and occurring in the interval of 0.2–3 sec after the stimulating effect).

The type of response is determined: hyporeactive type, if after the n-th (n = 1 ... 7) stimulating effect, three subsequent ones with numbers n + 1, n + 2, n + 3 do not cause reactive GSR (according to criterion 2.1), or addiction - in the event that reactive GSR occurs in response to a stimulating effect in at least 8 cases out of 10.

In the case of determining the response according to the type of addiction, for a number of values An ( _n = 1…10), the attenuation coefficient k is calculated, determined by the least squares method according to formula 1. Depending on the obtained numerical values for the patient, the risk of suicidal behavior is determined in accordance with the data indicated in table 1.

For a case that does not fall under the definition of hyporeactive type or habituation, it is not possible to draw a correct conclusion, and additional research is recommended.

So, for example, 10 stimulating actions are carried out, the results of which are evaluated as follows:

If responses (reactive GSR) are received only to the first three (only the first or only the first 2 or only the first 3) stimuli, and then there are no THREE responses in a row, then the risk is high. If responses are received to the first 4 (or 5 or 6 or 7) stimuli, and then there are no THREE responses, then the risk is moderate.

Stimulus: 1- 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10

Answer: 1- 2 - 3 - X - X - X- 7 - 8 - 9 - 10

Risk: high

Stimulus: 1- 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10

Answer: 1- 2 - 3 - 4 - 5 - X - X - X - 9 - 10

Risk: Moderate

If for 10 stimulating influences there are no three or more missed answers in a row (for example, there are only 1 or 2 missed answers), then we estimate by the attenuation coefficient k.

For example, if there are 5 answers, then one or two "passes", and then the answers are restored, then we count k.

Stimulus: 1- 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10

Answer: 1- 2 - 3 - 4 - 5 - X - 7 - 8 - X - 10

Risk: rated by k. At the same time, for an impact to which there was no response (in the example - the 6th (n = 6)) and, accordingly, it is impossible to determine its amplitude A, when substituting into the formula, the amplitude value is taken equal to 0.01.

If there are less than 8 responses to 10 stimuli, but there are no THREE "misses" in a row, then the results are not subject to evaluation.

Stimulus: 1- 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10

Answer: 1- 2 - 3 - 4 - 5 - X - 7 - X - X - 10

Not subject to evaluation.

Examples of the implementation of the method:

1. Patient P., 34 years old. Examined twice in a specialized hospital. Sent to a specialized psychiatric hospital from the Research Institute. Sklifosovsky with a diagnosis of schizotypal disorder, self-harm by hanging. F 21.8". He committed suicide spontaneously, without apparent reasons and critical reflection on the situation. "Active psychopathological symptoms could not be identified." According to the questionnaire "Assessment of suicidal risk: clinical signs" corresponds to "a very high risk of suicidal behavior." On the Beck Depression Scale, he scored 12 points (sub-depression), on the Peirce Intention Scale - 17 points (high level of suicidal intentions at the time of suicide), on the Beck Hopelessness Scale - 3 points (lack of despair). Conclusion of a medical psychologist: There is a high suicidal risk due to a combination of depressive tendencies, unformed criticality to one's condition and behavior, impulsiveness in actions, sensitivity, difficulties in recognizing one's emotions and sensations. Pathopsychological conclusion: the condition is characterized by a decrease in the background of mood, a feeling of despair, a pessimistic assessment of the future.

The patient was assessed for suicidal risk by registering the phasic components of EDA in response to subsensory stimulation according to the proposed method on the 4th day of observation. To do this, through the electrodes applied to the palmar surface of the hand, skin conductivity was recorded during stimulation. A total of 10 incentives were given. The interval between stimulating effects is 40±15 seconds. Characteristics of the stimulating effect: the duration of a package of 3 pulses - 120 ms, a single pulse - 20 ms, a repetition period - 40 ms. The pulse current amplitude is 150 µA, the current density is not higher than 150 µA/cm2 ^.

The following values of reactive GSR were obtained (GSR amplitudes, µS):

A ₁ \u003d 5.54; A ₂ \u003d 1.32; A ₃ \u003d 0.53; A ₄ \u003d 0.01; A ₅ \u003d 0.01; A ₆ \u003d 0.01; A ₇ \u003d 0.02; A ₈ \u003d 0.08; A ₉ \u003d 0.02; A ₁₀ \u003d 0.01.

According to the stated criteria, there were no reactive GSR in response to 4, 5, 6 stimulating effects.

The subject's reaction is of the hyporeactive type.

Calculation according to the established evaluation criteria: n= 3;

Conclusion: high risk of suicidal behavior, which coincides with the conclusion of a medical psychologist.

2. Subject P., aged 57. Examined twice in a psychophysiological laboratory. He reported that painful experiences appeared after the death of his wife, to whom he was tenderly attached. During a long serious illness, the wife looked after her, showed concern, until the last did not believe in a fatal outcome. For three months, he experiences “unimaginable longing”, “a feeling that the vital core has been taken out of the body”, “a feeling of emptiness and loss, as if time has stopped”. Occasionally, especially in the evenings, she experiences painful memories of "past happy relationships with her", she may cry. He blames himself for "did his best, but no more." Spontaneously says that without a spouse, "life has become empty, meaningless and it makes no sense to cling to it." When purposefully questioned about possible suicidal intentions, he declares “let it be, as it will, it makes no sense to cling to life”, but with a direct question about the presence of suicidal intention, he denies this, saying: “time must pass, it will put everything in its place”. Several times, he tried to smooth out the painful sensations by drinking alcohol, which only made it worse: the feeling of longing and loneliness, obsessive memories of his wife intensified. He began to spend more time at work, where he is distracted from painful experiences, “with his head” goes into the performance of professional duties. Despite the fact that he suffers from the experiences described above, he seeks sympathy and help, he refuses medical treatment (antidepressants), believing that "this needs to be experienced, I will bear my cross." Beck depression score = 13 points (sub-depression)

Conclusion of a psychiatrist: Adjustment disorder. F 43.2.

The subject was assessed suicidal risk by registering the phasic components of EDA in response to subsensory stimulation according to the proposed method. To do this, through the electrodes applied to the palmar surface of the hand, skin conductivity was recorded during stimulation. A total of 10 incentives were given. The interval between stimulating effects is 40±15 seconds. Characteristics of the stimulating effect: The duration of a package of 2 pulses - 80 ms, a single pulse - 20 ms, a repetition period - 40 ms. The pulse current amplitude is 150 µA, the current density is not higher than 150 µA/cm2 ^.

The following values of reactive GSR were obtained (GSR amplitudes, µS):

A ₁ \u003d 2.22; A ₂ \u003d 1.45; A ₃ \u003d 0.94; A ₄ =0.50; A ₅ \u003d 0.25; A ₆ \u003d 0.02; A ₇ \u003d 0.01; A ₈ \u003d 0.01; A ₉ \u003d 0.01; A ₁₀ \u003d 0.01.

According to the stated criteria, there is no reactive GSR in response to 7, 8, 9, 10 stimuli.

The subject's reaction is of the hyporeactive type.

Calculation according to the established evaluation criteria: n= 6;

Conclusion: moderate risk of suicidal behavior, which coincides with the conclusion of a psychiatrist.

3. Patient G., 58 years old. Examined in a specialized hospital. Honey. card No. 1208. In the last days before hospitalization, he experienced a feeling of worthlessness, apathy, considered himself "good for nothing." A few days before hospitalization, he took 50 tablets of phenazepam with suicidal intent. He was taken to the intensive care unit of the City Clinical Hospital No. N. I. Pirogov, from where he was transferred to a psychiatric hospital. During hospitalization, the diagnosis was made: “A severe depressive episode without psychotic symptoms. Suicidal attempt. F32.2". Beck Depression Scale = 34 overt depressive manifestations. Method for diagnosing the level of subjective feeling of loneliness Russell-Ferguson = 26 points. Suicidal motivation (Yu.R. Vagin) = 26 points; anti-suicidal motivation = 71 points. Despair scale (BeckHopelessnessScale) = 17 points, severe despair. The conclusion of a medical psychologist: Severe depressive symptoms with a high suicidal risk. Pathopsychological conclusion: the condition is characterized by a decrease in the background of mood, a feeling of despair, a pessimistic assessment of the future. In the personal sphere - a combination of sthenicity, anxiety, a high level of claims and demands on oneself and others, an increased level of critical self-assessment, instability of self-esteem and its dependence on achievements and external factors, a growing tendency to doubt and hesitation, an increase in affective rigidity. Neuropsychological study: modal-nonspecific memory impairment due to increased trace inhibition; exhaustion of mental processes; inertia of mental activity; violations of dynamic praxis; defects in visual gnosis. Electroencephalography: diffuse changes in the bioelectrical activity of the brain. Dysfunction of diencephalic-stem structures. The center of paroxysmal activity in the occipital region on the left and the frontal region on the right. Decrease in the threshold of convulsive readiness. Computed tomography: there are no data for focal changes in the brain tissue. The patient was assessed for suicidal risk by registering the phasic components of EDA in response to subsensory stimulation according to the proposed method on the 5th day of observation. To do this, through the electrodes applied to the palmar surface of the hand, skin conductivity was recorded during stimulation. A total of 10 incentives were given. The interval between stimulating effects is 40±15 seconds. Characteristics of the stimulating effect: The duration of a package of 4 pulses - 160 ms, a single pulse - 20 ms, a repetition period - 40 ms. The pulse current amplitude is 150 µA, the current density is not higher than 150 µA/cm2 ^.

The following values of reactive GSR were obtained (GSR amplitudes, µS):

A ₁ \u003d 0.89; A ₂ \u003d 0.53; A ₃ \u003d 0.27; A ₄ \u003d 0.17; A ₅ \u003d 0.09; A ₆ \u003d 0.07; A ₇ \u003d 0.05; A ₈ \u003d 0.02; A ₉ \u003d 0.01; A ₁₀ \u003d 0.01.

The reaction of the subject is of the type of habituation .

Calculation according to the established evaluation criteria: k = 0.5159.

Conclusion: high risk of suicidal behavior, which coincides with the conclusion of a medical psychologist.

4. Patient B., 26 years old. Examined twice during an outpatient visit to a specialized medical institution. Honey. card number 51-2019. After parting with her beloved man, she experienced “despair”, “terrible melancholy and depression”, sleep was disturbed, her appetite disappeared (“I can’t eat”). At work, she took a vacation “at her own expense”, because “she became absent-minded, inattentive, stopped coping with her professional duties”, constantly “thought about betrayal”. With a compass, she inflicted minor superficial damage to the skin in the area of \u200b\u200bthe inner surface of the forearm. She independently sought medical help from a psychiatrist. Diagnosis at admission: “Adaptation disorder. F43.2". Conclusion of a medical psychologist: against the background of sufficient indicators of mental performance and mental activity, a predominance of anxious and schizoid features is found, which exceed the normal level in severity: vulnerability, isolation, low self-esteem, orientation to subjective experiences. Emotional detachment and low stress resistance are combined with discomfort in the field of relationships and, at the same time, with a high need to establish close and deep interpersonal contacts. The patient was assessed suicidal risk by registering the phasic components of EDA in response to subsensory stimulation according to the proposed method on the 15th day of observation. To do this, through the electrodes applied to the palmar surface of the hand, skin conductivity was recorded during stimulation. A total of 10 incentives were given. The interval between stimulating effects is 40±15 seconds. Characteristics of the stimulating effect: The duration of a package of 2 pulses - 80 ms, a single pulse - 20 ms, a repetition period - 40 ms. The pulse current amplitude is 150 µA, the current density is not higher than 150 µA/cm2 ^.

The following values of reactive GSR were obtained (GSR amplitudes, µS):

A ₁ \u003d 1.55; A ₂ \u003d 1.12; A ₃ \u003d 1.27; A ₄ \u003d 0.74; A ₅ \u003d 0.52; A ₆ \u003d 0.63; A ₇ \u003d 0.36; A ₈ \u003d 0.27; A ₉ \u003d 0.18; A ₁₀ \u003d 0.12.

The reaction of the subject is of the type of habituation .

Calculation according to the established evaluation criteria: k = 0.2760.

Conclusion: moderate risk of suicidal behavior, which coincides with the conclusion of a medical psychologist.

5. Patient L., 34 years old. Examined twice: during an outpatient visit to a specialized medical institution and in a psychophysiological laboratory. Complains of regular nocturnal awakenings against the background of "depression", lack of "full sleep", "superficial sleep that does not bring rest." For several years in the autumn-winter time, he experiences a “decadent”, depressed mood (more in the morning), gets tired quickly, performs daily tasks with difficulty, “through force”, feels guilty for not being able to pay “enough attention” during these periods daughters." In spring and summer, she feels much better, experiences an increase in mood and physical strength, she is inclined to "perform spontaneous acts", sleeps little, but gets enough sleep, does not feel tired. Score on the Beck Depression Scale = 10 points, on the Hamilton Rating Scale for Depression (SIGH-SAD) - 20 points.

Conclusion of a psychiatrist: Cyclothymia with a pronounced seasonal pattern (Seasonal Affective Disorder) in a neurotic personality. F34.0.

The patient was assessed for suicidal risk by registering the phasic components of EDA in response to subsensory stimulation according to the proposed method. To do this, through the electrodes applied to the palmar surface of the hand, the skin conductivity was recorded during stimulation. A total of 10 incentives were given. The interval between stimulating effects is 40±15 seconds. Characteristics of the stimulating effect: The duration of a package of 3 pulses - 120 ms, a single pulse - 20 ms, a repetition period - 40 ms. The pulse current amplitude is 150 µA, the current density is not higher than 150 µA/cm2 ^.

The following values of reactive GSR were obtained (GSR amplitudes, µS):

A ₁ \u003d 0.95; A ₂ \u003d 1.09; A ₃ \u003d 0.94; A ₄ \u003d 0.69; A ₅ \u003d 0.48; A ₆ \u003d 0.51; A ₇ =0.47; A ₈ =0.45; A ₉ \u003d 0.36; A ₁₀ \u003d 0.21.

The reaction of the subject is of the type of habituation .

Calculation according to the established evaluation criteria: k = 0.1583.

Conclusion: low risk of suicidal behavior, which coincides with the assessment of the psychiatrist.

Claims (12)

1. A method for assessing the risk of suicidal behavior in terms of electrodermal activity, including the supply of stimulating effects by electric current applied to the skin, registration and evaluation of responses of electrodermal activity, characterized in that use a series of 10 stimulating effects of electric current applied to the skin on the palm or to the fingers, the interval between which is 40 ± 15 s, carry out exosomatic registration of skin conductivity; when registering responses of electrodermal activity, reactive phasic changes in electrodermal activity (EDA) are isolated and the amplitudes A _n of reactive galvanic skin reactions (GSR) are determined; moreover, if after the n-th stimulating effect, at n=1-3, the next three do not cause reactive GSR, then the risk of suicidal behavior is assessed as high; if after the n-th stimulus, at n=4-7, the next three do not cause reactive GSR, then the risk of suicidal behavior is assessed as moderate; at the same time, if reactive GSR occurs in response to the nth stimulus in at least 8 cases out of 10, then the attenuation coefficient k is calculated from the amplitudes A _n of reactive GSR, determined by the least squares method using the formula: k =

, the risk of suicidal behavior is assessed as high at k ≥ 0.5108, moderate at 0.5108 > k ≥ 0.2231, low at 0.2231 > k ≥ 0.05. 2. The method according to claim 1, characterized in that for stimulation, exposure to a single impulse of electric current with a duration of 10-20 ms, or exposure to a packet of rectangular pulses is used: the duration of an individual pulse in a pulse packet is 10-20 ms, the repetition period is 20-50 ms, packet duration 30-1000 ms, pulse current amplitude 50-500 μA, current density not higher than 500 μA/cm ² . 3. The method according to claim 1, characterized in that the exosomatic registration of skin conductivity is carried out in the range from 0.1 to 100 μS with a sampling frequency from 5 to 20 Hz. 4. The method according to claim 1, characterized in that the phasic component of skin conductivity includes an increase in skin conductivity for more than 0.3 s, which occurred in the interval of 0.2-3 s after the stimulus, and with an amplitude of more than 0.02 μS .

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