Summary: Greater exposure to screen time in early childhood was linked to poor self-regulation and brain immaturity at age eight.
Source: Agency for Science, Technology and Research
More and more children are now being exposed to mobile digital devices at a young age as a means of entertainment and distraction.
A longitudinal cohort study in Singapore has confirmed that excessive screen time in early childhood is linked to adverse effects on cognitive function, which continue to be apparent after the age of eight.
The research team looked at data from 506 children who enrolled in the Singapore Growing Up Towards Healthy Outcomes (GUSTO) Cohort Study since birth.
When children were 12 months old, parents were asked to report average screen time on weekdays and weekends each week. The children were then categorized into four groups based on screen time per day – less than an hour, one to two hours, two to four hours and more than four hours. At 18 months of age, brain activity was also collected using electroencephalography (EEG), a highly sensitive tool that tracks changes in brain activity.
In addition to undergoing the EEG, each child participated in various cognitive ability tests that measured their attention span and executive functioning (sometimes called self-regulation skills) at age nine.
The team first looked at the association between screen time and EEG brain activity. EEG readings revealed that infants exposed to longer screen time had greater “low frequency” waves, a condition correlated with lack of cognitive alertness.
To find out if screen time and observed changes in brain activity have adverse effects later in childhood, the research team analyzed all the data at three points for the same children – at 12 months. , 18 months and nine years. As the duration of screen time increased, the greater the altered brain activity and the more cognitive deficits were measured.
Children with executive function deficits often have difficulty controlling their impulses or emotions, maintaining their attention, following multi-step instructions, and persisting in a difficult task.
A child’s brain develops rapidly from birth through early childhood. However, the part of the brain that controls executive functioning, or the prefrontal cortex, has a longer development.
Executive functions include the ability to sustain attention, process information, and regulate emotional states, all of which are essential for learning and academic performance. The advantage of this slower growth of the prefrontal cortex is that the imprinting and formation of executive function skills can occur throughout the school years through to higher education.
However, this same area of the brain responsible for executive functioning abilities is also highly vulnerable to environmental influences over a long period of time.
This study indicates that screen time is one of the environmental influences that may interfere with the development of executive functions. Previous research suggests that infants have difficulty processing information on a two-dimensional screen.
When looking at a screen, the infant is bombarded with a stream of rapid movements, continuous flashing lights and scene changes, which require many cognitive resources to understand and process. The brain becomes “overwhelmed” and is unable to allow itself adequate resources to mature in cognitive skills such as executive functions.
The researchers also worry that families who allow very young children to spend hours in front of a screen often face additional challenges. These include stressors such as food or housing insecurity and parental mood issues. More work needs to be done to understand the reasons for excessive screen time in young children.
Further efforts are needed to distinguish the direct association of screen use in infants from familial factors that predispose early screen use to executive function disorders.
The study was a collaborative effort including researchers from Yong Loo Lin School of Medicine, National University of Singapore (NUS Medicine), Singapore Institute of Clinical Sciences (SICS), A*STAR , National Institute of Education, KK Hospital for Women and Children, McGill University and Harvard Medical School. It was published in JAMA Pediatrics on January 31, 2023.
Lead author Dr Evelyn Law of NUS Medicine and SICS Translational Neuroscience Program said: “The study provides compelling evidence to existing studies that our children’s screen time needs to be closely monitored, especially during early brain development. Dr. Law is also a consultant in the Division of Developmental and Behavioral Pediatrics at Khoo Teck Puat – National University Institute of Children’s Medicine, National University Hospital.
Professor Chong Yap Seng, Dean of NUS Medicine and Clinical Director, SICS, added: “These results from the GUSTO study should not be taken lightly as they impact the potential development of future generations and capital human.
“With these results, we are taking another step towards a better understanding of how environmental influences can affect children’s health and development. This would allow us to make more informed decisions to improve the health and potential of every Singaporean by giving every child the best start in life.
Professor Michael Meaney, Director of the Translational Neuroscience Program at SICS, said: “In a country like Singapore, where parents work long hours and children are exposed to frequent screens, it is important to study and understand the impact of screen time on children’s developing brains.”
About this technology and brain development research news
Author: Sharmaine Loh
Source: Agency for Science, Technology and Research
Contact: Sharmaine Loh – Agency for Science, Technology and Research
Picture: Image is in public domain
Original research: Free access.
“Associations Between Infant Screen Use, Electroencephalography Markers, and Cognitive Outcomes” by Evelyn Law et al. JAMA Pediatrics
Associations between infant screen use, electroencephalography markers, and cognitive outcomes
Research evidence is accumulating for the association between screen use in infants and negative cognitive outcomes related to attention and executive functions. The nature, timing, and persistence of screen time exposure on neural functions are currently unknown. Electroencephalography (EEG) helps to elucidate the neural correlates associated with cognitive disorders.
To examine associations between infant screen time, EEG markers, and school-age cognitive outcomes using mediation analysis with structural equation modeling.
Design, framework and participants
This prospective mother-child dyad cohort study included participants from the population-based Singapore Growing Up Towards Healthy Outcomes (GUSTO) study. Pregnant mothers were enrolled in their first trimester from June 2009 to December 2010. A subset of children who completed neurodevelopmental visits at ages 12 months and 9 years underwent an EEG at age 18 month. Data were reported from 3 time points at 12 months, 18 months and 9 years of age. Mediation analyzes were used to investigate how neural correlates were involved in pathways from infant screen time to the latent construction of attention and executive functioning. Data for this study was collected from November 2010 to March 2020 and was analyzed between October 2021 and May 2022.
Parent-reported screen time at 12 months of age.
Main results and measures
EEG power spectral density was collected at 18 months of age. Child attention and executive functions were measured with teacher-reported questionnaires and objective laboratory tasks at age 9 years.
In this sample of 437 children, the mean (SD) age at follow-up was 8.84 (0.07) years and 227 children (51.9%) were male. The mean (SD) amount of daily screen time at 12 months of age was 2.01 (1.86) hours. Screen time at 12 months of age contributed to multiple measures of attention and executive functioning over 9 years (η2, 0.03-0.16; Cohen D, 0.35-0.87). A subset of 157 children underwent an EEG at 18 months of age; EEG relative theta power and the theta/beta ratio in the frontocentral and parietal regions showed a graded correlation with screen use over 12 months (r= 0.35-0.37). In the structural equation model controlling for household income, fronto-central and parietal theta/beta ratios partially mediated the association between screen time and school-age executive functioning (exposure-mediator β, 0.41; 95% CI, 0.22 to 0.59; mediator-outcome β, -0.38; 95% CI, -0.64 to -0.11), forming an indirect path that represented 39.4% of the association.
Conclusions and relevance
In this study, screen use in infants was associated with impaired cortical EEG activity by age 2; identified EEG markers mediated the association between infant screen time and executive functions. Further efforts are urgently needed to distinguish the direct association of screen use in infants versus familial factors that predispose early screen use to executive function disorders.