Tuesday, October 1, 2019

Effects of Cell Phone Use on Adolescents

Long-Term Symptoms of Mobile Phone Use on Mobile Phone Addiction 
and Depression Among Korean Adolescents



Park SY, Yang S, Shin CS, Jang H, Park SY. Long-Term Symptoms of Mobile Phone Use on Mobile Phone Addiction and Depression Among Korean Adolescents. Int J Environ Res Public Health. 2019 Sep 25;16(19). pii: E3584. doi: 10.3390/ijerph16193584.
 
Abstract

This study aimed to compare the mean scores of mobile phone use, mobile phone addiction, and depressive symptoms at three-time points among Korean adolescents according to gender and to examine the differences in the long-term relationships among the three above-mentioned variables between Korean boys and girls in a four-year period. Data for 1794 adolescents (897 boys and 897 girls) were obtained from three waves of the second panel of the Korean Children and Youth Panel Survey. Multigroup structural equation modeling was used for data analyses. The study findings showed that at each of the three-time points, Korean girls tended to use their mobile phones more frequently and were at a higher risk of mobile phone addiction and depressive symptoms than Korean boys. Significant changes were observed in the longitudinal relationships among phone use, mobile phone addiction, and depressive symptoms in Korean adolescents across time periods, but no gender differences were found in the strengths of these relationships. These findings contribute to expanding the knowledge base of mobile phone addiction and depressive symptoms among Korean adolescents.


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Short-term longitudinal relationships between smartphone use/dependency 
and psychological well-being among late adolescents

Lapierre MA, Zhao P, Custer BE. Short-term longitudinal relationships between smartphone use/dependency and psychological well-being among late adolescents. Journal of Adolescent Health (2019). DOI: 10.1016/j.jadohealth.2019.06.001

Abstract

Purpose  The aim of the study was to determine the short-term longitudinal pathways between smartphone use, smartphone dependency, depressive symptoms, and loneliness among late adolescents.

Methods A two-wave longitudinal survey was used using adolescents between the ages of 17 and 20 years. The interval between wave 1 and wave 2 was between 2.5 and 3 months. Using convenience sampling, the total number of participants who completed both waves of data collection was 346. Validated measures assessed smartphone dependency, smartphone use, depressive symptoms, and loneliness. The longitudinal model was tested using path modeling techniques.

Results Among the 346 participants (33.6% male, mean [standard deviation] age at wave 1, 19.11 [.75] years, 56.9% response rate), longitudinal path models revealed that wave 1 smartphone dependency predicted loneliness (β = .08, standard error [SE] = .05, p = .043) and depressive symptoms (β = .11, SE = .05, p = .010) at wave 2, loneliness at wave 1 predicted depressive symptoms at wave 2 (β = .21, SE = .05, p < .001), and smartphone use at wave 1 predicted smartphone dependency at wave 2 (β = .08, SE = .05, p = .011).

Conclusions Considering the rates of smartphone ownership/use among late adolescents (95%), the association between smartphone use and smartphone dependency, and the deleterious effects of loneliness and depression within this population, health practitioners should communicate with patients and parents about the links between smartphone engagement and psychological well-being. 


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Night-time screen-based media device use and adolescents' sleep 
and health-related quality of life

Mireku MO, Barker MM, Mutz J, Dumontheil I, Thomas MSC, Roosli M, Elliott P, Toledano MB. Night-time screen-based media device use and adolescents' sleep and health-related quality of life. Environ Int. 2019 Mar;124:66-78. doi: 10.1016/j.envint.2018.11.069

Abstract

OBJECTIVE: The present study investigates the relationship between night-time screen-based media devices (SBMD) use, which refers to use within 1 h before sleep, in both lit and dark rooms, and sleep outcomes and health-related quality of life (HRQoL) among 11 to 12-year-olds.

METHODS: We analysed baseline data from a large cohort of 6616 adolescents from 39 schools in and around London, United Kingdom, participating in the Study of Cognition Adolescents and Mobile Phone (SCAMP). Adolescents self-reported their use of any SBMD (mobile phone, tablet, laptop, television etc.). Sleep variables were derived from self-reported weekday and/or weekend bedtime, sleep onset latency (SOL) and wake time. Sleep quality was assessed using four standardised dimensions from the Swiss Health Survey. HRQoL was estimated using the KIDSCREEN-10 questionnaire.

RESULTS: Over two-thirds (71.5%) of adolescents reported using at least one SBMD at night-time, and about a third (32.2%) reported using mobile phones at night-time in darkness. Night-time mobile phone and television use was associated with higher odds of insufficient sleep duration on weekdays (Odds Ratio, OR = 1.82, 95% Confidence Interval, CI [1.59, 2.07] and OR = 1.40, 95% CI [1.23, 1.60], respectively). Adolescents who used mobile phones in a room with light were more likely to have insufficient sleep (OR = 1.32, 95% CI [1.10, 1.60]) and later sleep midpoint (OR = 1.64, 95% CI [1.37, 1.95]) on weekends compared to non-users. The magnitude of these associations was even stronger for those who used mobile phones in darkness for insufficient sleep duration on weekdays (OR = 2.13, 95% CI [1.79, 2.54]) and for later sleep midpoint on weekdays (OR = 3.88, 95% CI [3.25, 4.62]) compared to non-users. Night-time use of mobile phones was associated with lower HRQoL and use in a dark room was associated with even lower KIDSCREEN-10 score (β = -1.18, 95% CI [-1.85, -0.52]) compared to no use.

CONCLUSIONS: We found consistent associations between night-time SBMD use and poor sleep outcomes and worse HRQoL in adolescents. The magnitude of these associations was stronger when SBMD use occurred in a dark room versus a lit room.


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Prolonged mobile phone use is associated with depressive symptoms in Chinese adolescents

Liu J, Liu C, Wu T, Liu BP, Jia CX, Liu X. Prolonged mobile phone use is associated with depressive symptoms in Chinese adolescents. J Affec Disord. 12(259):128-134. Aug 2019. DOI: 10.1016/j.jad.2019.08.017.

Abstract

Background: Prolonged screen time has negative impacts on health and well-being. This study examined the association between the duration of mobile phone use (DMPU) and depressive symptoms in a large sample of Chinese adolescents.

Methods: 11,831 adolescent students participated in the baseline Shandong Adolescent Behavior and Health Cohort (SABHC) survey in Shandong, China in 2015. A self-administered questionnaire was used to measure DMPU on weekdays and the weekend, sleep, mental health, and family environment. The Centre for Epidemiologic Studies Depression Scale (CES-D) and Youth Self-Report (YSR) depression scales were used to assess depressive symptoms.

Results: The mean age of participants was 15.0 (SD = 1.5) and 51% were male. The prevalence of depressive symptoms increased with prolonged DMPU. After adjusting for adolescent and family covariates, DMPU ≥ 2 h/day on weekdays (OR = 1.78, 95%CI = 1.48-2.15) and ≥ 5 h/day on the weekend (OR = 1.67, 95%CI = 1.41-1.98) was associated with increased risk of depressive symptoms as assessed by CES-D. The DMPU-depression association was found to be partially mediated by short sleep duration or insomnia. Similar associations were observed for depression as assessed by YSR.

Study Limitation: This is a cross-sectional survey. Mobile phone use and depressive symptoms were measured by self-report.

Conclusions: Prolonged mobile phone use of ≥ 2 hours on weekdays and ≥ 5 hours on the weekend is associated with an increased risk of depressive symptoms. The association appears to be partially mediated by sleep disturbances.

https://www.ncbi.nlm.nih.gov/pubmed/31450134

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Problematic cell phone use, depression, anxiety & self-regulation: 
3-year longitudinal study from adolescence to emerging adulthood

Coyne SM, Stockdale L, Summers K. Problematic cell phone use, depression, anxiety, and self-regulation: Evidence from a three year longitudinal study from adolescence to emerging adulthood. Computers in Human Behavior. 96:78-84. July, 2019.

Highlights

• Problematic cell phone use is stable between adolescence and emerging adulthood.
• Self-regulation and problematic cell phone use are not longitudinally related.
• Early problematic cell phone use is moderately associated with later depression.

Abstract

For a small percentage of cell phone users, cell phone use becomes problematic or addictive, characterized by excessive time spent on the cell phone, interference with social relationships and responsibilities, and difficulty disengaging from cell phones. Researchers have argued that depression, anxiety, and self-regulation may be risk factors or outcomes of problematic cell phone use, but there are few longitudinal studies on problematic cell phone use, making it unclear if these behaviors are predictors or outcomes of problematic cell phone use. The current study examined these factors during late adolescence and the transition to emerging adulthood. Participants included 385 individuals between the ages of 17 and 19 who completed a series of questionnaires once a year over a three year period. Problematic cell phone use, anxiety, depression, and self-regulation were all moderately associated at the cross-sectional level. Early problematic cell phone use predicted later depression when these variables were examined longitudinally, as opposed to the converse. There were no longitudinal associations between problematic cell phone use and anxiety or self-regulation. In sum, problematic cell phone use was fairly stable across the transition from adolescence to emerging adulthood and was associated with depression in the future.


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Social media use and adolescent mental health: Findings From the UK Millennium Cohort Study

Kelly Y, Zilanawala A, Booker C, Sacker A. (2019) Social media use and adolescent mental health: Findings from the UK Millennium Cohort Study. EClinicalMedicine. 10.1016/j.eclinm.2018.12.005. 2019. (In press)

Abstract

BACKGROUND: Evidence suggests social media use is associated with mental health in young people but underlying processes are not well understood. This paper i) assesses whether social media use is associated with adolescents' depressive symptoms, and ii) investigates multiple potential explanatory pathways via online harassment, sleep, self-esteem and body image.

METHODS: We used population based data from the UK Millennium Cohort Study on 10,904 14 year olds. Multivariate regression and path models were used to examine associations between social media use and depressive symptoms.

FINDINGS: The magnitude of association between social media use and depressive symptoms was larger for girls than for boys. Compared with 1–3 h of daily use: 3 to < 5 h 26% increase in scores vs 21%; ≥ 5 h 50% vs 35% for girls and boys respectively. Greater social media use related to online harassment, poor sleep, low self-esteem and poor body image; in turn these related to higher depressive symptom scores. Multiple potential intervening pathways were apparent, for example: greater hours social media use related to body weight dissatisfaction (≥ 5 h 31% more likely to be dissatisfied), which in turn linked to depressive symptom scores directly (body dissatisfaction 15% higher depressive symptom scores) and indirectly via self-esteem.

INTERPRETATION: Our findings highlight the potential pitfalls of lengthy social media use for young people's mental health. Findings are highly relevant for the development of guidelines for the safe use of social media and calls on industry to more tightly regulate hours of social media use.

FUNDING: Economic and Social Research Council.

Excerpt

Among 14-year olds living in the UK, we found an association between social media use and depressive symptoms and that this was stronger for girls than for boys. The magnitude of these associations reduced when potential explanatory factors were taken into account, suggesting that experiences of online harassment, poorer sleep quantity and quality, self-esteem and body image largely explain observed associations. There was no evidence of differences for girls and boys in hypothesised pathways between social media use and depressive symptoms. Findings are based largely on cross sectional data and thus causality cannot be inferred.

Open access paper: http://iris.ucl.ac.uk/iris/publication/1621800/1

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Telecommunication devices use, screen time and sleep in adolescents

Cabre-Riera A, Torrent M, Donaire-Gonzalez D, Vrijheid M, Cardis E, Guxens M. Telecommunication devices use, screen time and sleep in adolescents. 171:341-347. Apr 2019. DOI: 10.1016/j.envres.2018.10.036

Highlights

• Telecommunication and other screen devices use was collected in adolescents
• Both subjective and objective sleep measures were assessed
• Tablet use and mobile phone dependency were associated with poorer sleep
• Frequency of cordless phone calls was associated with poorer sleep
• Public health recommendations on telecommunication devices use should be a priority

Abstract

Purpose To investigate the association between telecommunication and other screen devices and subjective and objective sleep measures in adolescents at 17–18 years.

Methods Cross-sectional study on adolescents aged 17–18 years from a Spanish population-based birth cohort established in Menorca in 1997–1998. Information on devices use was collected using self-reported questionnaires. Mobile Phone Problematic Use Scale was used to assess mobile phone use dependency. Pittsburgh Sleep Quality Index was used to assess subjective sleep (n=226). ActiGraph wGT3X-BT for 7 nights was used to assess objective sleep (n=110).

Results One or more cordless phone calls/week was associated with a lower sleep quality [Prevalence Ratio PR 1.30 (95%CI 1.04; 1.62)]. Habitual and frequent problematic mobile phone use was associated with a lower sleep quality [PR 1.55 (95%CI 1.03; 2.33) and PR 1.67 (95%CI 1.09; 2.56), respectively]. Higher tablet use was associated with decreased sleep efficiency and increased minutes of wake time after sleep onset [β −1.15 (95%CI −1.99; −0.31) and β 7.00 (95%CI 2.40; 11.60) per increase of 10 minutes/day of use, respectively]. No associations were found between other devices and sleep measures.

Conclusions Tablet use, mobile phone use dependency, and frequency of cordless phone were related to an increase of subjective and objective sleep problems in adolescents. These results seem to indicate that sleep displacement, mental arousal, and exposure to blue light emission might play a more important role on sleep than a high RF-EMF exposure to the brain. However, more studies are needed assessing personal RF-EMF levels to draw conclusions.
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Cohort study of adolescents' memory performance & brain dose of microwave radiation from wireless EMF

Foerster M., Thielens A., Joseph W., Eeftens M., Röösli M. A prospective cohort study of adolescents' memory performance and individual brain dose of microwave radiation from wireless communication. Environmental Health Perspectives.126(7):077007. 2018. DOI: 10.1289/EHP2427.


Abstract

BACKGROUND: The potential impact of microwave radiofrequency electromagnetic fields (RF-EMF) emitted by wireless communication devices on neurocognitive functions of adolescents is controversial. In a previous analysis, we found changes in figural memory scores associated with a higher cumulative RF-EMF brain dose in adolescents.

OBJECTIVE: We aimed to follow-up our previous results using a new study population, dose estimation, and approach to controlling for confounding from media usage itself.

METHODS: RF-EMF brain dose for each participant was modeled. Multivariable linear regression models were fitted on verbal and figural memory score changes over 1 y and on estimated cumulative brain dose and RF-EMF related and unrelated media usage (n=669–676). Because of the hemispheric lateralization of memory, we conducted a laterality analysis for phone call ear preference. To control for the confounding of media use behaviors, a stratified analysis for different media usage groups was also conducted.

RESULTS: We found decreased figural memory scores in association with an interquartile range (IQR) increase in estimated cumulative RF-EMF brain dose scores: −0:22 (95% CI: −0:47, 0.03; IQR: 953 mJ=kg per day) in the whole sample, −0:39 (95% CI: −0:67, −0:10; IQR: 953 mJ=kg per day) in right-side users (n=532), and −0:26 (95% CI: −0:42, −0:10; IQR: 341 mJ=kg per day) when recorded network operator data were used for RF-EMF dose estimation (n=274). Media usage unrelated to RF-EMF did not show significant associations or consistent patterns, with the exception of consistent (nonsignificant) positive associations between data traffic duration and verbal memory.

CONCLUSIONS: Our findings for a cohort of Swiss adolescents require confirmation in other populations but suggest a potential adverse effect of of RF-EMF brain dose on cognitive functions that involve brain regions mostly exposed during mobile phone use. 

Conclusion

We found preliminary evidence suggesting that RF-EMF may affect brain functions such as figural memory in regions that are most exposed during mobile phone use. Our findings do not provide conclusive evidence of causal effects and should be interpreted with caution until confirmed in other populations. Associations with media use parameters with low RF-EMF exposures did not provide clear or consistent support of effects of media use unrelated to RF-EMF (with the possible exception of consistent positive associations between verbal memory and data traffic duration). It is not yet clear which brain processes could be potentially affected and what biophysical mechanism may play a role. Potential long-term risk can be minimized by avoiding high brain-exposure situations as occurs when using a mobile phone with maximum power close to the ear because of, for example, bad network quality.

Note: The original study appears below (Schoeni et al., 2015).

Open access paper: https://ehp.niehs.nih.gov/EHP2427/

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Decreases in sleep duration among U.S. adolescents 2009-2015 & association with new media screen time

Twenge JM, Krizan Z, Hisler G. Decreases in self-reported sleep duration among U.S. adolescents 2009-2015 and association with new media screen time. Sleep Med. 2017 Nov;39:47-53. doi: 10.1016/j.sleep.2017.08.013.

Highlights

• More adolescents in 2015 (vs. 2009) slept less than 7 h a night on most nights.
• Electronic device and social media use also increased in 2009–2015.
• Electronic device and social media use increases the odds of short sleep duration. 
• Smartphones may be the cause of the increase in self-reported short sleep duration.

Abstract



STUDY OBJECTIVES: Insufficient sleep among adolescents carries significant health risks, making it important to determine social factors that change sleep duration. We sought to determine whether the self-reported sleep duration of U.S. adolescents changed between 2009 and 2015 and examine whether new media screen time (relative to other factors) might be responsible for changes in sleep.

METHODS:We drew from yearly, nationally representative surveys of sleep duration and time use among adolescents conducted since 1991 (Monitoring the Future) and 2007 (Youth Risk Behavior Surveillance System of the Centers for Disease Control; total N = 369,595).

RESULTS: Compared to 2009, adolescents in 2015 were 16%-17% more likely to report sleeping less than 7 h a night on most nights, with an increase in short sleep duration after 2011-2013. New media screen time (electronic device use, social media, and reading news online) increased over this time period and was associated with increased odds of short sleep duration, with a clear exposure-response relationship for electronic devices after 2 or more hours of use per day. Other activities associated with short sleep duration, such as homework time, working for pay, and TV watching, were relatively stable or reduced over this time period, making it unlikely that these activities caused the sudden increase in short sleep duration.

CONCLUSIONS: Increased new media screen time may be involved in the recent increases (from 35% to 41% and from 37% to 43%) in short sleep among adolescents. Public health interventions should consider electronic device use as a target of intervention to improve adolescent health.


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The effects of EMF on the endocrine system in children and adolescents

Sangün Ö, Dündar B, Çömlekçi S, Büyükgebiz A. The effects of electromagnetic field on the endocrine system in children and adolescents. Pediatr Endocrinol Rev. 2015 Dec;13(2):531-45.

Abstract


Children are exposed to various kind of non-ionizing radiation in their daily life involuntarily. The potential sensitivity of developing organism to the effects of radiofrequency (RF) signals, the higher estimated specific absorption rate (SAR) values of children and greater lifetime cumulative risk raised the scientific interest for children's vulnerability to electromagnetic fields (EMFs). In modern societies, children are being exposed to EMFs in very early ages. There are many researches in scientific literature investigating the alterations of biological parameters in living organisms after EMFs. Although the international guidelines did not report definite, convincing data about the causality, there are unignorable amount of studies indicating the increased risk of cancer, hematologic effects and cognitive impairment. Although they are less in amount; growing number of studies reveal the impacts on metabolism and endocrine function. Reproductive system and growth look like the most challenging fields. However there are also some concerns on detrimental effects of EMFs on thyroid functions, adrenal hormones, glucose homeostasis and melatonin levels. It is not easy to conduct a study investigating the effects of EMFs on a fetus or child due to ethical issues. Hence, the studies are usually performed on virtual models or animals. Although the results are conflicting and cannot be totally matched with humans; there is growing evidence to distress us about the threats of EMF on children.

http://1.usa.gov/1QhY253


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Does exposure to environmental RF EMF cause cognitive & behavioral effects in 10-year-old boys?

Calvente, I., Pérez-Lobato, R., Núñez, M.-I., Ramos, R., Guxens, M., Villalba, J., Olea, N. and Fernández, M. F. (2016), Does exposure to environmental radiofrequency electromagnetic fields cause cognitive and behavioral effects in 10-year-old boys?. Bioelectromagnetics, 37: 25–36. doi: 10.1002/bem.21951.

Abstract


The relationship between exposure to electromagnetic fields from non-ionizing radiation and adverse human health effects remains controversial. We aimed to explore the association of environmental radiofrequency-electromagnetic fields (RF-EMFs) exposure with neurobehavioral function of children.

A subsample of 123 boys belonging to the Environment and Childhood cohort from Granada (Spain), recruited at birth from 2000 through 2002, were evaluated at the age of 9–11 years. Spot electric field measurements within the 100 kHz to 6 GHz frequency range, expressed as both root mean-square (S
RMS) and maximum power density (SMAX) magnitudes, were performed in the immediate surrounds of children's dwellings. Neurocognitive and behavioral functions were assessed with a comprehensive battery of tests. Multivariate linear and logistic regression models were used, adjusting for potential confounders.

All measurements were lower than reference guideline limits, with median S
RMS and SMAX values of 285.94 and 2759.68 μW/m2, respectively. Most of the cognitive and behavioral parameters did not show any effect, but children living in higher RF exposure areas (above median SRMS levels) had lower scores for verbal expression/ comprehension and higher scores for internalizing and total problems, and obsessive-compulsive and post-traumatic stress disorders, in comparison to those living in areas with lower exposure. These associations were stronger when SMAX values were considered.

Although some of our results may suggest that low-level environmental RF-EMF exposure has a negative impact on cognitive and/or behavior development in children; given limitations in the study design and that the majority of neurobehavioral functioning tasks were not affected, definitive conclusions cannot be drawn.


http://onlinelibrary.wiley.com/doi/10.1002/bem.21951/abstract

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November 19, 2015

Two recently published studies on adolescents report harmful effects of mobile phone use. A cross-sectional study found that adolescents who were awakened by a mobile phone at least once a month during the night were more likely to report tiredness, rapid exhaustibility, headache and physical ill-being. A prospective cohort study found that greater wireless radiation exposure predicted lower memory test performance.

Symptoms & cognitive functions in adolescents in relation to mobile phone use

Schoeni A, Roser K, Röösli M. Symptoms and cognitive functions in adolescents in relation to mobile phone use during night. PLoS One. 2015 Jul 29;10(7):e0133528. doi: 10.1371/journal.pone.0133528.

Abstract

Many adolescents tend to leave their mobile phones turned on during night, accepting that they may be awakened by an incoming text message or call. Using self-reported and objective operator recorded mobile phone use data, we thus aimed to analyze how being awakened during night by mobile phone affects adolescents' perceived health and cognitive functions.

In this cross-sectional study, 439 adolescents completed questionnaires about their mobile phone use during night, health related quality of life and possible confounding factors. Standardized computerized cognitive tests were performed to assess memory and concentration capacity. Objective operator recorded mobile phone use data was further collected for 233 study participants. Data were analyzed by multivariable regression models adjusted for relevant confounders including amount of mobile phone use.

For adolescents reporting to be awakened by a mobile phone during night at least once a month the odds ratio for daytime tiredness and rapid exhaustibility were 1.86 (95% CI: 1.02-3.39) and 2.28 (95% CI: 0.97-5.34), respectively. Similar results were found when analyzing objective operator recorded mobile phone use data (tiredness: 1.63, 95% CI: 0.94-2.82 and rapid exhaustibility: 2.32, 95% CI: 1.01-5.36). The cognitive tests on memory and concentration capacity were not related to mobile phone use during night. Overall, being awakened during night by mobile phone was associated with an increase in health symptom reports such as tiredness, rapid exhaustibility, headache and physical ill-being, but not with memory and concentration capacity.

Prevention strategies should focus on helping adolescents set limits for their accessibility by mobile phone, especially during night.

Conclusion

Among Swiss adolescents, we have observed that nocturnal mobile phone use was associated with an increase in health symptom reports such as tiredness, rapid exhaustibility, headache and physical ill-being, but not with memory and concentration capacity. More studies to investigate these associations are necessary and education in sleep behaviour may be inevitable since the mobile phone is now the most familiar lifestyle factor for adolescents.

Public Health prevention strategies should focus on helping adolescents set limits for their accessibility by mobile phone, especially during night.

Open Access Paper: http://1.usa.gov/1NeP2lJ

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Memory performance, wireless communication & RF EMF exposure: Prospective cohort study in adolescents

Schoeni A, Roser K, Röösli M. Memory performance, wireless communication and exposure to radiofrequency electromagnetic fields: A prospective cohort study in adolescents. Environ Int. 2015 Oct 13;85:343-351. doi: 10.1016/j.envint.2015.09.025.

Highlights

• This is a prospective cohort study with approx. one year of follow-up.
• Self-reported and operator recorded mobile phone use data were collected.
• The cumulative RF-EMF dose for the brain and for the whole body was calculated.
• Associations were stronger for RF-EMF dose than for use of wireless devices.
• RF-EMF exposure might impair memory performance in adolescents.

Abstract

BACKGROUND: The aim of this study is to investigate whether memory performance in adolescents is affected by radiofrequency electromagnetic fields (RF-EMF) from wireless device use or by the wireless device use itself due to non-radiation related factors in that context.

METHODS: We conducted a prospective cohort study with 439 adolescents. Verbal and figural memory tasks at baseline and after one year were completed using a standardized, computerized cognitive test battery. Use of wireless devices was inquired by questionnaire and operator recorded mobile phone use data was obtained for a subgroup of 234 adolescents. RF-EMF dose measures considering various factors affecting RF-EMF exposure were computed for the brain and the whole body. Data were analysed using a longitudinal approach, to investigate whether cumulative exposure over one year was related to changes in memory performance. All analyses were adjusted for relevant confounders.

RESULTS: The kappa coefficients between cumulative mobile phone call duration and RF-EMF brain and whole body dose were 0.62 and 0.67, respectively for the whole sample and 0.48 and 0.28, respectively for the sample with operator data. In linear exposure-response models an interquartile increase in cumulative operator recorded mobile phone call duration was associated with a decrease in figural memory performance score by -0.15 (95% CI: -0.33, 0.03) units. For cumulative RF-EMF brain and whole body dose corresponding decreases in figural memory scores were -0.26 (95% CI: -0.42, -0.10) and -0.40 (95% CI: -0.79, -0.01), respectively. No exposure-response associations were observed for sending text messages and duration of gaming, which produces tiny RF-EMF emissions.

CONCLUSIONS: A change in memory performance over one year was negatively associated with cumulative duration of wireless phone use and more strongly with RF-EMF dose. This may indicate that RF-EMF exposure affects memory performance.

http://1.usa.gov/1M6BCHW


Excerpts

... From a public health point of view potential effects of chronic exposure are more relevant, which needs to be investigated with epidemiological studies. So far there has only been one community-based epidemiological study investigating effects of mobile phone use on adolescents' memory. Abramson et al. (2009) showed in a cross-sectional analysis of 317 seventh grade students from Australia that mobile phone use was associated with faster and less accurate response on a number of tasks involving the memory. Since similar associations were found in relation to the number of SMS (short text messages), which produces negligible RF-EMF exposure, they speculated that these behaviours may have been learned through the frequent use of a mobile phone and may not be the consequence of mobile phone radiation. In a follow-up investigation one year later, in 236 of these students, an increase in mobile phone use was associated with a reduction in response time in one out of three tests involving the memory (Thomas et al., 2010). This study relied on self-reported mobile phone use only, which has been shown to be inaccurate. Adolescents tend to substantially overestimate their amount of mobile phone use (Aydin et al., 2011; Inyang et al., 2009).

Regular mobile phone use may affect adolescents in various ways. Thus, the main challenge for research consists in differentiating between RF-EMF radiation effects and other non-RF-EMF related effects from mobile phone use. For instance, frequent texting or gaming on a mobile phone may facilitate cognitive processes (Abramson et al., 2009). It was also observed, that calling and sending texts during night was associated with poor perceived health symptoms such as tiredness, rapid exhaustibility, headache and physical ill-being (Schoeni et al., 2015; Van den Bulck, 2007). Other studies showed that frequent mobile phone use was associated with anxiety (Jenaro et al., 2007), unhealthy lifestyle (Ezoe et al., 2009), depression (Yen et al., 2009) and psychological distress (Beranuy et al., 2009). Thus, to address RF-EMF effects of wireless communication devices, the development of a RF-EMF dose measure, which incorporates all exposure relevant factors, is inevitable.


Memory performance was assessed with a standardized, computerized cognitive test battery (IST, Intelligenz-Struktur-Test 2000R (Liepmann et al., 2006)). Verbal and figural memory was measured with the subtest of the IST. In the verbal memory task, word groups have to be memorized in one minute time. After 1 min the study participants give an account of the word groups that have been memorized. In total 10 points can be achieved by remembering the correct word groups. In the figural memory task, pairwise symbols have to be memorized in one minute time. After 1 min one part of the pairwise symbols is shown and the matching part has to be found. A total of 13 points can be achieved. For both the verbal and figural tests, 2 min is given to complete the test. Memory performance is considered as the right number of remembered word groups or symbols, respectively. For the statistical analyses of verbal and figural memory the continuous test score values
were used as outcome. Every test was conducted once at baseline and once at follow-up investigation.

In this study we considered objectively recorded data on mobile phone use collected from the Swiss mobile phone operators as well as self-reported data on wireless communication devices usage obtained from a written questionnaire referring to the 6 months period prior to each examination. In terms of RF-EMF related exposure measures we inquired about call duration with own or any other mobile phone (referred to as duration mobile phone calls), call duration with cordless (fixed line) phone and duration of data traffic on the mobile phone, e. g. for surfing and streaming. The duration of gaming on computers and TV and number of all kind of text messages (SMS, WhatsApp etc.) are not, or only marginally relevant for RF-EMF exposure and were thus inquired to be used as negative exposure control variables in the analyses.

Informed consent to obtain objectively recorded mobile phone use data from the mobile phone operators was given by 234 out of 439 study participants and their parents. This included duration of each call and on which network (GSM or UMTS) it started, number of SMS (text messages) sent per day and amount of volume of data traffic (MB/day). Data were obtained for up to 18 months, 6 months before baseline until follow-up investigation.

A particular strength of this study is the longitudinal design. To the best of our knowledge this is the first longitudinal study on memory performance in adolescents using not only mobile phone call duration as an exposure proxy, but calculating RF-EMF dose measures derived from objectively recorded operator data and propagation modelling. Compared to a cross-sectional design where changes over time cannot be assessed andwhere reverse causality is of concern, longitudinal studies allow for more robust conclusions.

.. Most relevant contributors for the brain dose are calls on the GSM network (on average 93.3% for the whole sample based on self-reported data and 58.7% for the sample with operator data using operator recorded information) followed by calls with the cordless phones (4.2% and 21.0%, respectively). For the whole body dose, calls on the GSM network (on average 66.9% for the whole sample and 19.5% for the sample with operator data), the use of computer/laptop/tablet connected to WLAN (12.0% and 29.1%, respectively) and data traffic on mobile phones over WLAN (8.1% and 22.3%, respectively) counted for the most part. Less important for the dose measures were exposure from radio and TV broadcast transmitters (brain dose: 0.1% and 0.4%, respectively; whole body dose: 0.3% and 0.9%, respectively) and mobile phone base stations (brain dose: 0.6% and 3.5%, respectively; whole body dose: 2.0% and 4.8%, respectively).

... media usage measures which are not, or only marginally associated with RF-EMF were not associated with figural memory performance (e.g. sending text messages, playing games, and duration/volume of data traffic on the mobile phone). On the other hand, mobile and cordless phone use,which involves RF-EMF exposure, tended to be negatively correlated, although not statistically significant, whereas the dose measures were significantly correlated in many models. The relative high correlation between dose measures and self-reported and objectively recorded mobile phone call duration respectively, limits the possibility to disentangle effects due to RF-EMF exposure or due to other factors associated with mobile phone use.

Since we found stronger associations between RF-EMF doses and figural memory but not verbal memory, one could speculate that this might be due to different brain areas involved in the verbal and figural memory tasks. The type of information being processed determines the brain activity during encoding and retrieval and as a consequence brain activity patterns during figural memory tasks differ fromthose observed during verbal memory tasks. During figural memory processes, encoding elicits bilateral prefrontal activity and retrieval increases the activity in bilateral or right-sided temporal regions and in bilateral prefrontal regions (Beason-Held et al., 2005; Roland and Gulyas, 1995; Wagner et al., 1998). During verbal encoding increases in prefrontal and temporal brain activity in the left hemisphere can be seen (Heun et al., 2000; Iidaka et al., 2000; Reber et al., 2002; Strandberg et al 2011) and during verbal retrieval the activity in bilateral or rightsided prefrontal regions, bilateral or left-sided temporal regions and the anterior cingulate are increased (Beason-Held et al., 2005; Buckner et al., 1998; Cabeza et al., 1997). Stronger overall effects observed for figural memory processes predominantly involving the right hemisphere compared to the verbal memory tasks mostly involving the left hemisphere is compatible with the fact that 81.2% of the study participants reported at follow-up to mainly use mobile phones on the right side but only 18.8% on the left side or with no laterality preference. Strikingly, our laterality analyses indicated indeed stronger associations for right side users for the figural memory task whereas the reverse pattern was seen for the verbal task. However, the sample size of the laterality analysis was small for the subgroup with left side or no side preference for mobile phone use (n= 80).

We considered a number of potential confounders and adjusted model estimates were relatively similar to the crude model estimates, which indicates that confounding seems not to have a substantial impact on the results. Nevertheless, we cannot exclude that we have missed a relevant confounder ....

Conclusion

The observed striking pattern with more consistent associations for RF-EMF dose measures compared to usage measures and no indications of associations for negative control exposure variables may indicate that RF-EMF exposure affects the figural memory of adolescents. However, given the complex correlation structure for various exposure measures and the uncertainty in the RF-EMF dose calculation, the observed associations need to be interpreted with caution.