Effects of auditory training on cognitive function in patients with stroke

Effects of Auditory Training on Cognitive Function in Patients with Stroke Zhang Jingjing, Chen Changxiang, Li Shuxing, Zhang Min, Dou Na Project of Technological Support Funded by Science and Technology Department of Hebei (13277748D) School of Nursing and Rehabilitation, North China University of Science and Technology, 063000 Hebei, China Correspondence Author: Professor Chen Changxiang, E-mail: hlxccx@163.com.

DOI:10.3760/cma.j.issn.1674-6554.2016.

Abstract Objective: This experiment aims to explore rehabilitative effects of Tomatis® training on cognitive impairments among patients with stroke.

Methods: A total of 80 stroke patients with cognitive impairments were sampled and divided into the control group (n=40) and the experimental group (n=40). Both groups received Tomatis® audio training in combination with conventional intervention, while the only difference between the interventions was that the music tracks used in the control group was not specially modified. Montreal Cognitive Assessment (MoCA) was conducted before and after the training.

Results: After a two-week session of Tomatis® training, improvement of the overall condition and each tested aspect of the experimental group, evaluated by the MoCA scores, was statistically significant (P<0.01); as to the control group, the participants also showed improvement with significance(P<0.05) in the aspects of memory, executive functions, visuospatial ability, abstract thinking and the overall condition. Moreover, the comparison between groups revealed that improvement occurred in the experimental group in each individual aspect and the overall condition was significantly (P<0.05) substantial than that of the control group.

Conclusion: Tomatis® audio training can enhance the cognitive functions of patients with stroke.

Key words: Stroke; Cognitive Impairment; Tomatis® Audio Training About 75% of all survivors of stroke, which incidence has been rising by the year, are suffering from cognitive impairments, and such conditions consequently affect their everyday life and the outcome of rehabilitation [1]. Currently, computer-assisted cognitive training and trans-cranial magnetic stimulation therapy are currently available for Chinese patients with cognitive dysfunction after stroke while virtual reality technology and somatosensory games are the main intervention chosen in Western countries [2,3].

The delivery of the aforementioned conventional trainings is highly restricted by the trainers’ profession, the treatment environment and the patients’ condition. On the other hand, Tomatis® audio training [4], developed by a French doctor named Alfred Tomatis® , is simple to deliver and does not put strict requirements on the environment.

It employs modified music to induce stimulation on the cortex in order to improve

cognitive function.

TomatisÂŽ training has been applied in other countries in cases of psychological and cognitive dysfunction [5], but data about its effects on the post-stroke cognitive impairments are still lacking. It is based on such grounds that this research was designed and conducted.

1 Subjects and Methods 1.1 Subjects Between August and December in 2015, 87 inpatients with stroke were initially selected from the Rehabilitation Department in Tangshan Gongren Hospital, while 4 discontinued the experiment and 3 were discharged from the hospital due to unexpected causes. Eventually, data from 80 participants were collected and analyzed.

The inclusion criteria were: diagnosis of stroke based on the standard established by The 4th Conference of Chinese Cerebrovascular Disease[6] in 1995 and confirmed by clinical examinations, age between 35 and 75, absence of moderate or severe encephalatrophy or leukoaraiosis, first onset, the course of disease being less than three months, score of MoCA<26, absence of consciousness disorder, no history of mental disorder, certain level of education ensuring the participants to be able to fully comprehend common words and language, and a signed version of informed consent.

Patients with severe audiovisual dysfunction, inadequate language competence, severe organ dysfunction, malignant tumors, other critical conditions, mental disorder, intellectual retardation, coma, hospital stay being less than 2 months and addiction to drugs or alcohol were excluded.

2 Methods 2.1 Evaluation MoCA[7] scores, designed by Nasreddine in 2004 and translated into Chinese in 2007

by Wang Wei and his team, of all participants were obtained before and after the experiment. In total, 11 aspects of 8 cognitive-function domains including attention, concentration, executive function, memory, language, visuospatial ability, abstract thinking, numeracy and spatial orientation were evaluated. With a total score of 30, results lower than 26, the cutoff score, were regarded as indicative of the presence of cognitive impairments [8]. By MoCA scale, a rapid screening of abnormal cognitive function could be conducted with high reliability and validity.

2.2 Grouping The sample composed 80 inpatients with stroke (52 males and 28 females) with an average age of 56.8Âą8.6. Among all the participants, there were 55 cases of cerebral infarction and 25 cerebral hemorrhage; as to the location of the lesions, 32 participants were on the left, 35 on the right and 13 on both sides.

The participants were evenly and randomly assigned into the experimental group (n=40) and the control group (n=40). The difference between these two groups in demographic information, course of disease, nature of disease and sides of lesions was not statistically significant (P > 0.05) (see Table 1).

Table 1 Comparison between Two Groups on Demographic Information

Sex

Age/Year

Educational Background

Marital Status

Occupation

Time

since

Onset

Experimental Group

Control Group

(n=40)

(n=40)

Male

25

27

Female

15

13

35~

2

3

45~

16

15

55~

10

14

65~

12

8

None

15

14

Primary or Junior High School

17

19

Senior High School and Above

8

7

Married

28

32

Divorced or Widowed

12

8

Mainly Mental

26

22

Mainly Manual

14

18

1~

12

16

2~

18

16

3~

10

8

Cerebral Infarction

30

25

Cerebral Hemorrhage

10

15

Left

15

17

Right

19

16

Bilateral

6

Statistical

Data

P

0.2201)

0.815

1.6991)

0.637

0.2121)

0.899

1.0671)

0.439

0.8331)

0.494

0.9111)

0.634

1.4551)

0.335

0.4591)

0.795

0.6162)

0.539

/Month

Nature of Disease

Sides of Lesions

MoCA Score

13.48±3.030

7 3)

13.05±3.1373)

2.3 Intervention Both groups received Tomatis® training in combination with conventional rehabilitation, including occupational therapy, physical therapy, transcutaneous electrical nerve stimulation, treatment on neural network plasticity and acupuncture.

The only difference between the interventions on those groups was that the music tracks used in the experimental group were specially modified as designed in the original Tomatis® training [9].

The device used in this experiment was “TalksUp (SN: 150103-0000472)” developed by the Tomatis® research institution in France. Specially, the training apparatus consisted of 2 hosts (a green-marked one installed with specially modified music for the experimental group and a red-marked one with regular music for the control group) with touch screens, 2 wireless transmitters matched with hosts, and wireless headsets with additional vibrators for bone conduction (BC). This combination enabled that more than one participants can receive the training simultaneously.

For the training, 10 to 16 participants would be gathered within the coverage (about a 30-meter radius) of the wireless transmitter, and research staff was in charge of turning on the headsets, adjusting the volume and putting the headsets correctly on the patients, ensuring the bone conductor be placed at the center of the parietal bone and

two sides of the headsets differentiated.

The program used in this experiment, designed by a medical doctor of Neurocognitive Psychology in Marseille University in France, included Mozart tracks and Gregorian chants (GC), and during training session, the music contents varied from day to day, the change of which was also operated by the research staff.

There were foreign researches showing that Mozart music can stimulate the brain and “activate” neural circuits [10] while Gregorian chants can sooth and relax the autonomic nervous system [5].

Specifically, the program of Tomatis® training used in this experiment involved 3 stages.

Stage 1 was designed to for participants to adapt to the training, therefore the frequencies changed in a gradual mode to prepare the participants for the later, more intensive session. For such a purpose, program T was used, once a day, 60 minutes for the first 3 days and 90 minutes from day 4 and onwards. The music tracks consisted of 35% non-filtered music (MU), 26% mixed voice and GC, 21% low band-pass with a cutoff frequency of 6000HZ (Low BP) and 18% universal band-pass with the cutoff frequencies of 500HZ and 3000HZ (BPU1).

(2) Stage 2 was planned as a break between two sessions of intensive training, allowing enough time for the brain and the body to assimilate and integrate the changes induced by stimulation [11].

(3)Stage 3 was the essential stage, since till then the brain of the participants had gradually adapted to the stimulation caused by changes in frequency. This stage last for 10 days, with a daily session of 90 minutes. The music formula chosen for this stage was made up of 60% MU, 25% GC and 15% Low BP. The principle of Tomatis® training is the perceptual contrast, realized by switching between two audio channels, Channel 1 (C1) which features high frequencies and Channel 2 (C2) which features low frequencies in both air conduction (AC) and BC, and thus the frequencies of the music constantly vary across the spectrum between 20Hz and 16000Hz. The time required to switch from C1 to C2 by BC is called “delay” while that in AC, once the switching in BC has finished, is named “precession”, and the gating speed is the sum of delay and precession. The constant alternation between these two channels in both AC and BC induce a large amount of stimulation onto the brain and other parts of the central nervous system [5].

2.4 Statistical Methods Statistical software SPSS17.0 was used to test normal distribution and homogeneity of variance of collected data and then to conduct t test on measurement data (x±s) and x2

test on enumeration data. “P＜0.05” was set as the standard to determine whether

the difference was statistically significant.

3 Results 3.1 Changes of MoCA Scores of the Experimental Group and Control Group After the Tomatis® training, improvement in the experimental group evaluated by the MoCA scores of the overall condition and each tested aspect was statistically

significant (P<0.01); as to the control group, the participants also showed improvement with significance(P<0.05) in the aspects of memory, executive functions, visuospatial ability, abstract thinking and the overall condition (see Table 2).

Table 2 Improvements of Cognitive Functions after Training Experimental Group

Control Group (U=40)

(U=40) Before

After

t

P

Before

After

t

P

Attention & Concentration 2.20±0.56 2.60±0.59 -5.099

0.000 2.15±0.66 2.20±0.69 -1.433

0.160

Memory Exective Function

2.38±0.81 2.85±0.83 -5.940 1.33±0.97 1.85±1.00 -5.992

0.000 2.20±0.68 2.30±0.72 -2.082 0.000 1.20±0.88 1.38±0.93 -2.211

0.044 0.033

Language

1.35±0.58 1.80±0.79 -5.649

0.000 1.35±0.70 1.40±0.71 -1.433

0.160

Visuospatial Ability

1.50±0.88 2.10±0.87 -6.000

0.000 1.53±0.75 1.73±0.78 -3.122

0.003

Abstract Thinking Numeracy Spatial Orientation

1.00±0.68 1.53±0.68 -5.547 1.53±0.72 2.00±0.55 -5.421 2.15±0.83 2.70±0.85 -6.904

0.000 1.08±0.62 1.23±0.62 -2.623 0.000 1.48±0.85 1.53±0.85 -1.433 0.000 2.20±0.88 2.23±0.86 -1.000

0.012 0.160 0.323

Overall Condittion

13.48±3.28 17.43±4.11 -11.831

0.000 13.25±3.15 14.05±3.32 -5.099

0.000

3.2 Comparison between MoCA Scores of the Experimental Group and Control Group after Training The negligible (P>0.05) difference between all MoCA scores of the two groups before the training gained statistical significance (P<0.05) after the training (See table 3).

Table 3 Comparison between MoCA Scores of Two Groups after the Training Experimental Group （n=40) 2.60±0.59

Control Group （n=40) 2.20±0.69

t

P

2.793

0.007

Memory

2.85±0.83

2.30±0.72

3.152

0.002

Executive Function

1.85±1.00

1.38±0.93

2.204

0.030

Language

1.80±0.79

1.40±0.71

2.382

0.020

Visuospatial Ability

2.10±0.87

1.73±0.78

2.024

0.046

Abstract Thinking

1.53±0.68

1.23±0.62

2.064

0.042

Numeracy

2.00±0.56

1.53±0.85

2.967

0.004

Spatial Orientation

2.70±0.85

2.23±0.86

2.477

0.015

Overall Condition

17.43±4.11

14.05±3.32

4.042

0.000

Attention & Concentration

4 Discussion Cognitive impairments, caused by local brain damage during the stroke which is usually the result of hypoxia and ischemia, are mainly manifested as difficulties in remembering, learning and executive functioning [12]. Consequently, both daily activities and rehabilitation of those patients are unfavorably affected.

It has been reported that chronic stress responses toward the stroke can produce monoamine neurotransmitter, which will influence the function of the prefrontal cortex [13] and that the structure and function of such damaged tissues on the central nervous system are highly plastic. Therefore, the impaired cognitive function can be restored and strengthened through training [3].

The results of this study shows that the participants in the control group improved significantly(P<0.05) in the aspects of memory, executive functions, visuospatial ability, abstract thinking and the overall condition, which indicates that the combination of conventional intervention and Tomatis® training with regular music tracks can relieve cognitive impairments in patients with stroke.

However, the changes in executive function, visuospatial ability and abstract thinking

were not greater than the effects achieved by conventional intervention alone[14] while the addition of Tomatis® training and its efficacy was highlighted by the comparatively pronounced improvement in the aspect of memory [10].

As to the experimental group, the improvement evaluated by the MoCA scores of the overall condition and each tested aspect was significant and significantly (P<0.05) substantial than that of the control group. In such light, it can be concluded that as compared to convention music therapy, original Tomatis® training can effectively improve cognitive functions in patients with stroke.

The device used for Tomatis® training is highly sophisticated, because: ① AC and BC can be realized by one headset, while the latter will facilitate the sound reception [15]; ② the music tracks used are specially modified.

The mechanism of Tomatis® training can be summarized as follows. ① The sound across the spectrum can induce stimulation onto the limbic system located at the central region of the brain, which is responsible for emotion, memory and knowledge acquisition; ② High frequency sounds energize the cortex through the cochlea, and during the process the limbic system and the prefrontal cortex can be activated, resulting in a rise in efficiency of auditory working memory [16]. Therefore, the impairments that interfere with cognitive function, psychological well-being, language or balance can be alleviated. ③ Music tracks and their modification vary from session to session in order to keep the participants interested in the training. As a result, the brain will always receive fresh stimulation caused by changes in sound frequencies and cognitive functions will eventually be enhanced. ④ The soothing and relaxing feature of music will further facilitate rehabilitation.

Tomatis® training is a convenient intervention not strictly limited by location and environment. With wireless device, several patients can receive the training simultaneously, making this intervention time- and cost-effective. More importantly, under a relaxing atmosphere, the patient can benefit from this training without potential side effects. However, limitations on time and sample size necessitate further researches to identify long-term efficacy of Tomatis® training.

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