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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 6  |  Issue : 2  |  Page : 173-177

Effects of 30-min mobile use on selected brain function tests in female medical students


Department of Physiology, KIMSDU, Karad, Maharashtra, India

Date of Submission21-Nov-2020
Date of Decision27-Apr-2021
Date of Acceptance08-May-2021
Date of Web Publication08-Jan-2022

Correspondence Address:
Dr. Anuya Anand Joshi
KIMSDU, Karad, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/bjhs.bjhs_121_20

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  Abstract 


INTRODUCTION: Today, mobile phones (MPs) have become an indispensable tool because of the countless perks it provides. In India, there are more than a million MP users. When compared with total telecommunication users, MPs users are 88%. Extensive use of MP has led to exposure to a dangerous level of electromagnetic waves. Many investigations concluded that MP use reduces the cognitive function of the human brain, however, there is a difference of opinion within the research workers. The present research work can be used to plan the large-scale study which will be useful to decide safety limits and advice for advocating safety measures.
MATERIALS AND METHODS: For the present study, 240 female medical students (age group: 18–23 years) from KIMS, Karad, were studied. Durations of visual reaction time, trail making test A and B, and letter cancellation test were studied. Digit span test scores were also measured. All the parameters were studied before and after 30-min mobile use.
RESULTS: It was observed that there was a highly significant decrease in values of all the parameters studied (P < 0.001) after 30 min of mobile use.
CONCLUSION: The present study showed that 30 min of mobile exposure affects the brain function. Hence, the large-scale study with more duration of exposure and large sample size is required to find conclusive results.

Keywords: Brain function tests, medical students, mobile use


How to cite this article:
Joshi AA. Effects of 30-min mobile use on selected brain function tests in female medical students. BLDE Univ J Health Sci 2021;6:173-7

How to cite this URL:
Joshi AA. Effects of 30-min mobile use on selected brain function tests in female medical students. BLDE Univ J Health Sci [serial online] 2021 [cited 2022 Jul 2];6:173-7. Available from: https://www.bldeujournalhs.in/text.asp?2021/6/2/173/335321



Today, mobile phones (MPs) have become an indispensable tool because of the countless perks it provides. Today, a total number of MP users are more than one million in India. Out of total telecommunication users, MPs account for 88%. After the year 2019, a total number of MP users in the world will be more than five billion marks. It is expected that a number of MP users will reach to 67% at the end of 2019.[1],[2] A number of MP users expected to reach almost 1.5 billion in China and in India almost 1.1 billion by the year 2019.[3]

MPs are low-powered radiofrequency transmitters. The common operating range frequencies of MPs are between 450 and 2700 MHz. Peak powers of mobile are in the range of 0.1–2 watts. Extensive use of MP has led to exposure to a dangerous level of electromagnetic waves. Even the World Health Organization classified the radiofrequency electromagnetic radiation field emitted from wireless phones under Group 2 B-carcinogen category. Due to this fact, a number of countries have developed health-based precautionary guidelines for exposure of electromagnetic field (EMF) from cell phones and towers including India.[3] Electrophysiological investigations such electroencephalogram, evoked potentials, and electronphotonic imaging suggest that MP use is associated with changed brain hemodynamics and functions.[4],[5],[6] Baharara et al. observed that acute exposure to pulsed microwaves in mice leads to impairment in spatial reference memory.[7]

There is a difference of opinion within the research workers for effects of mobile use on brain functions. Kalafatakis et al. observed that MP use for 5 min can cause significant memory impairment in humans.[8] Jun Zhang observed that acute MP use is associated with cortical excitement.[9] Ishihara et al. observed that MP use is not associated with change in cognitive function of brain.[10]

Hence, in the present research work some, of the brain functions were studied. Hence, the objectives of the study were to measure the durations of visual reaction time (RT), trail making test (TMT) A and TMT B, and letter cancellation test and to measure the scores of digit span tests scores. All the durations and values were studied before and after 30-min mobile use.


  Materials and Methods Top


Inclusion criteria

Apparently healthy female medical students of age group 18–23 years and willing to participate were included in the study.

Exclusion criteria

History of taking any drugs such as antihistamines and sleeping pills (which may affect their performance for any of the tests); subjects' suffering from central nervous system disorders, endocrine disorders, psychiatric disorder, or any major illness; and diminished vision or colorblindness were excluded from the study.

For the present study, 240 female medical students (age group 18–23 years) were studied.

Institutional ethical committee approval was taken (KIMSDU/IEC/01/2015) for the present study. The average height of participants was 161.23 ± 6.22 cm, the average weight was 59.48 ± 10.8 kg, and the average body mass index was 22.96 ± 4.22.

Written consent was obtained. The study was done in morning hours from 10 a.m. to 12 a.m., an hour after light breakfast. Students were instructed not to use MP for minimum 12 h. The detail history and general and systemic examination of each subject was carried out carried to check for inclusion criteria. The subjects were well informed about the procedure of determination of various tests. The following tests were carried out: letter cancellation test RT, TMT A and TMT B, and digit span test. All the tests were carried out before mobile use. Then, students were asked to talk on mobile for 30 min. Students were instructed to talk common subjects which will not bring out any emotion such a fear or anger. Mobile was kept very close to right ear pinna while talking. Immediately after talking for 30 min, all the tests were repeated in the same sequence. Mobile model used for the study was Samsung Galaxy J7 Prime Android. SAR value head was 0.646 w/kg.

Letter cancellation test

Subjects were shown English alphabets and were told to cancel out specific letters. Time required to complete the task was measured.[11]

Trail making test A and B

Trail making test

The TMT consists of two parts. For TMT A, the subject has to draw lines in sequence connecting 25 encircled numbers distributed on a sheet of paper. For TMT B, nearly the same instructions except the student must alternate between numbers and letters (e.g., 1, A, 2, B, 3, C, etc.). For both the tests, final score is time required to complete the task.[12]

Digit span test

Subjects are asked to listen a sequence of numerical digits. After listening the digits, subjects were instructed to recall the sequence correctly. In subsequent trials, longer sequences being tested. The maximum number of digits that the subject recalls back is final score. Digit span tests consist of forward and backward.

Digits forward

Subjects are instructed to recall the numbers. Digits should be given at the rate of one per second. Recite digits without any variation in pitch of voice. At the rate of one per second, loudly random letters are readout. At the beginning of the tests, two to three numbers were presented slowly the numbers were increased. When the subject can not recall the numbers discontinue the test after failure. The maximum number of digits the subject recalled is observed.

Digits backward

The same procedure which was followed for digit forward test was implemented,but subjects were asked to repeat these numbers from backward. The score is the maximum number of such digits that the patient is able to reverse.[13]

Visual reaction times

The subjects were well informed about the procedure of determination of RT. Google app was used for visual RTs: Subjects were given adequate time for familiarizing with the instrument and procedure. For determination of visual RT, first tap to begin the test. When the red color changes to green color , tap again as soon as you can. The procedure was repeated for three times, and the least reading of the three was taken as subject's best visual RT.[14]


  Discussion Top


For immediate effects of mobile use, durations of TMT A and TMT B, visual RT, and letter cancellation test and values of digit span test were studied. All the tests were carried out before mobile use and after 30 min of mobile talk. It was observed [Table 1] that there was a significant decrease in mean values of durations of visual RT, TMT A and TMT B, letter cancellation test, and scores of digit span tests.
Table 1: Effect of 30 min of mobile use on trail making test test (A), trail making test test (B), letter cancellation, test digit span test, and visual reaction time

Click here to view


Reaction time

When receptors are stimulated, axons of neurons carry the impulse to brain, from the brain to the spinal cord and then to person's hands and fingers. RT is independent of social-cultural influences and can purely indicate the efficiency or dysfunction of biological process in brain.[15]

Factors that can affect the average human RT include physiological variations such as age, sex, and personality types. Other important factor thatcan affect human RT includes exercise, intelligence of the subject, level of fatigue, fasting, left or right hand, central vision, or peripheral vision. As the study was done on the same individuals before and after mobile use, so it minimizes all other errors.[16]

In the present study, the mean and standard deviation of subjects for visual RT was before 335 ms ± 5 and after it was 318 ms ± 55; P < 0.001 means statistically highly significant. The quickness of response depends on the integrity of cell communication, sensory perception, central processing, and motor response and movement time. It is the total time that elapses from the onset of the stimulus until the movement is completed. The significant decrease in RT (visual) after mobile use can be because of improved concentration, alertness, and better muscular co-ordination.[14]

Hence, mobile use for 30 min improves the RT, means performance is faster. Hence, mobile use rather than having detrimental effect it activates the brain. Further research is required to fix mechanism of EMF radiation on brain activation. There is a controversial finding of various research workers regarding the effects of mobile use on RT.[15],[17],[18],[19] Hence, research on large sample size is required to come to a conclusion.

In case of TMT A, [Table 1] the time required to complete the task before mobile use was 22.723 ± 6.346 s and after mobile use was 20.347 ± 6. P <0.001 means statistically highly significant. In case of TMT B, the time required to complete the task before mobile use was 34.177 ± 11.88 s and after mobile use was 30.819 ± 9.40. P < 0.001 means statistically highly significant. Hence, after mobile use, one can complete the task faster. The TMTs are popular neuropsychological instruments used either alone as a screening instrument for detecting neurological disease and neuropsychological impairment or as part of a larger battery of tests.

The study of TMT gives information about executive functions and also ability of visual search, scanning. It also provides information about speed of processing and mental flexibility. Here also one can say that 30 min of mobile use activates the brain and brain works faster.[6],[20],[21],[22]

Letter cancellation test

In case of letter cancellation test, [Table 1] the time required to complete the task before mobile use was 38.117 ± 12.478 s and after mobile use was 32.38 ± 11.453 s. P <0.001 means statistically highly significant. Hence, after mobile use, one can complete the task faster. Here also one can say that 30 min of mobile use activates the brain and brain works faster. The mean value for omission was 3.16 ± 2.55 and after mobile use was 2.99 ± 2.62; P > 0.05 means not significant. The mean value for commission was 3.004 ± 0.06 and after mobile use was 3.006 ± 0.07; P > 0.05 means not significant. Hence, it indicates that after mobile use, brain works faster, but there is no increase in errors. Cancellation tasks involve sustained attention, concentration, visual scanning, and activation and inhibition of rapid responses.[11]

Digit span test

for digit span test forward, the mean value of maximum number of digits that the subject could recall correctly before mobile use was [Table 1] 6.216 ± 2.366, and after mobile use, it was 5.408 ± 2.75. P <0.001 means statistically highly significant. For digit span test backward, the mean value of maximum number of digits that the subject could recall before mobile use was 4.90 ± 2.664 and after mobile use was 3.72 ± 2.076; P < 0.001 means statistically highly significant. As the number of letters recalled is reduced for digit span test forward and digit span test backward, it indicates that 30 min of mobile use affects short-term memory. Short-term memory is reduced. It is observed that working memory performance is reduced after MP use. The present results are similar to previous studies on animals and humans.[23] Animal studies also showed increased time to locate a submerged in water maze. Spatial reference memory was reduced in the mouse after acute exposure to pulsed microwaves.[7] There are reports stating that EMF exposure improves short-term memory.[22] In conclusion, there is controversial finding of various research workers regarding the effects of mobile use on short-term memory, so further research on large sample size is required to come to a conclusion.

Cell phones transmit radio waves in all directions. The waves can be absorbed and reflected by surrounding objects before they reach the nearest cell tower. For example, when the phone is placed next to your head during a call, a significant portion (over half in many cases) of the emitted energy is absorbed into your head and body. When using MP, electromagnetic wave is transferred to the body, near ear skull region where they are known to affect the neurons. The radiations interfere with the electrical impulses that two neurons connect each other. Absorption of radio waves leads to elevation of tissue temperature. The temperature rise can affect physiologic function of the body, which is sometimes beneficial to health, but can also result in adverse health effects. Various mechanisms are explained for effects of radio waves on neurons. Probable modes of EMF action are explained on the basis of oxidative stress (OS). Imbalance of reactive oxygen species and antioxidants is brought out by OS. In conclusion, OS is responsible disruption of cell functions.[22],[23],[24]


  Conclusion Top


The present study showed that mobile exposure affects the brain function. Few of the tests showed improvements in performance and few of the tests showed negative impact. Hence, the large-scale study with more duration of exposure and large sample size is required to find conclusive results.

Acknowledgment

The authors are thankful to dean KIMS and the head of the Department of Physiology, Karad, for providing laboratory facilities to carry out this research.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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