Abstract
Introduction
Technological advances over the last few decades have probably had a much bigger impact on our lives than we had imagined or were indeed prepared for. Our association with screens began as early as the 1950s with the arrival of television into everyday life. Gradually with the advent of laptops, smartphones, and tablets, we now use screens for a lot of our daily activities including work, games, watching videos, gathering information, etc. Digital media has now become an intricate part of modern life. It is a constantly evolving field and children and adolescents have taken to it quite effortlessly. Given the speed at which it has entered our lives, we have had little time to evaluate how it will impact the next generation. There have been concerns regarding the impact of digital technology on early brain development especially as the popular media is quick to establish negative causative links. Socrates once warned about how writing might reduce people’s capacity to memorize information. Partly, this skepticism reflects the resistance our society puts in when confronted with any new technology but the research is more nuanced. 1 The purpose of this review is to summarize the current evidence and conceptual understanding in this area.
Importance of Early Years
Brain development starts in utero at around 2 weeks and continues well into early adulthood. 2 This happens initially through neurogenesis, migration of neurons, synaptogenesis, and creation of billions of new synaptic connections that are essential for the development of a range of skills. In utero, development is mostly genetic although the intrauterine environment plays an important part. Humans have twice as many synapses at 2 to 3 years of age as compared to adults. A significant part of brain development involves pruning away the synapses and neurons till early adulthood. Environmental influences become extremely important for pruning as they interact with the genetic makeup in myriad ways. While early postnatal development and maturation of brain functions is strongly dependent on experience, later exposure to those experiences cannot make up for the earlier loss. There are many examples to illustrate this. 6 months old children can potentially discriminate between 2 monkey faces and human faces but by 9 to 12 months they can only discriminate between human faces if they are not regularly exposed to monkeys. This is because after a certain period, the brain at least partly loses its capacity to learn certain skills. This period is often referred to as the critical period. Similarly, a 6 months old child can discriminate between sounds of any language. But by 12 months, discrimination is limited to the language a child is exposed to. The 1st few (5–6) years are thought to reflect the critical period for the development of the child’s first language. Childhood is therefore a period of immense potential but also of vulnerability to adverse environmental influences. It is therefore understandable to be skeptical about the impact of any new technology especially if it becomes a significant part of our growing up environment.
Extent of Use of Digital Technology
It can be somewhat difficult to estimate the extent of use of digital technology given the differences in terminology. The traditional media devices include television and video games. Gradually, conventional television is being replaced by streaming services like Netflix, Amazon Prime, Hotstar, etc. These can be viewed on a phone, tablet, or a laptop. These devices can also be used to view more conventional television, watch videos on a variety of platforms, socialize on apps such as Facebook, Instagram, Snapchat, and play video games. Understandably, such has been the impact of these smart devices that it has blurred the differentiation between different types of digital technology. Most current literature therefore uses the phrase “screen time” (ST) to reflect this lack of differentiation. Given this heterogeneity, it makes it more difficult to interpret the effects of digital technology on the various aspects of brain development. The vast appeal of screen based smart devices because of their versatility has been hugely responsible for a significant spike in the exposure to electronic social media in the last few decades. 3
A recent community based cross sectional study of 550 adolescents in Delhi found that 98% were using screen based media (SBM) with a mean time of 3.8 h/day. 4 While this may not be surprising, data on younger children perhaps does raise eyebrows. A study on 15 to 18 months old children from the Delhi urban population found that in their study population of 370 mother-baby pairs, all except one toddler was exposed to SBM starting as early as 2 months. 5 Most common was smartphone use (96%) followed by television (89%) with 90% on their screens for more than 1 h/day. Most (266/370) parents were not concerned and only 2 parents had any knowledge of recommendations on exposure to ST at this age. SBM was mostly used to engage the child as the primary caregiver was too busy. This is a worrying trend as it means that screens are being used as proxy parents rather than to complement parenting skills.
Effects on Brain Development
Children these days are exposed to digital media very early on, often as early as 4 to 5 months. There have been various studies that have highlighted the association of excessive digital technology with early brain development.6,7 A recent study from India on more than 700 children less than 5 years of age found that increasing ST was significantly associated with developmental delay and that language and communication were especially affected. 8 However, the association is not quite as straightforward as it might seem. For instance, a French cohort study of more than 1500 children aged 2 to 6 years old found a cross-sectional inverted U-shaped association between children’s daily ST at age 2 years and language development. 9 Interestingly children who were watching screens for intermediate durations had the best language scores suggesting that ST in moderation can have a positive effects on language development.
Excessive ST, as expected, is also associated with poor quality and duration of sleep which over the years can have a significant effect on the development and overall behavior of children. 10 Excessive ST was associated with sleep induction problems, less night time sleep, and more daytime sleep. This can probably be explained because of late night watching, overstimulation before sleeping hours, scary content, and bright blue light of screens that can suppress melatonin. Notably, with more time spent with books, the opposite pattern occurred that is less daytime sleep, better quality and duration of sleep.
A number of studies have linked excessive ST to specific developmental disorders, including autism and ADHD. Some studies have backed this up by doing brain scans which have also shown the negative effects of excessive ST in young children. A cross-sectional study of 47 neurotypical children aged 3 to 5 years, found that incre- ased use of SBM was associated with children’s cognitive difficulties and decreased microstructural integrity of the brain white matter tracts that support language, executive functions, and literacy skills on DTI. 11 Most notable findings were observed in arcuate fasciculus, inferior longitudinal fasciculus, and uncinate fasciculus. As expected, it is impossible to causally link SBM to these brain findings and it is quite likely that these findings reflect the effects of poor parenting practices instead. Exposure to excessive ST in the early age group may have an effect on brain plasticity, but it needs more evidence before any clear conclusions can be drawn. 12
Links Between Screen Time and Autism Spectrum Disorders (ASD)
In the last 2 decades, the prevalence rate of ASD has risen steadily and is currently estimated to be around 1 in 68 children. Children on the spectrum have a strong inclination towards the use of electronic media. 13 Additionally, these children receive an unparalleled daily exposure to electronic media which begins as early as infancy.14,15 The genetic associations of ASD are very well established but there is a dearth of research on nongenetic causes. 16 Multiple studies report that excessive use of digital media is associated with social and communication difficulties seen in ASD. A recent study assessing over 2000 children in the first 2 years of their life revealed that greater screen exposure and less caregiver and child play in this early period of life was associated with ASD symptoms at 2 years when media exposure was as early as 1 year. 17 Another study done recently in China concluded that there was a positive correlation between ST and the severity of sensory symptoms and developmental delays especially language in children with ASD. 18 However, a recent study concluded that the observed effects on language development on children may be transient and disappear when they became toddlers. 19
Difficulties in social communication and emotional reciprocity are core features of children on the autism spectrum. It is observed that children who stay at home more often and use media without restriction have poor social communication skills as compared to others who engage in more face-to-face interactions that involve interpreting facial expressions and nonverbal cues. 20 Another research group found that digital media usage is linked with poorer quality of friendships, trust, disrupted communication, increased rate of peer conflict, and feelings of alienation which are common difficulties seen in children on the autism spectrum. 21 A few other studies have also highlighted the adverse effects of ST in the form of poor social participation along with poor behavioural control which are already problematic for children with ASD.22,23
The American Academy of Pediatrics has advised against the use of digital devices before 2 years of age and limits the ST of children aged 2 to 5 years of age to 1 hour per day. 24 However, it is important to also understand other relevant factors rather than just focusing on the duration of ST. Numerous studies have found that association is not just about the time spent on digital technology but also on the quality of exposure. Observations in preschoolers reveal that digital media may be effectively used as an active educational learning tool but only in the presence of equal amounts of parental interactions. 25 However, early child development depends a lot on the quality of overall environmental experience. This predominantly translates into parenting practices early on. The development of language and overall communication depends on the quality of interactive exchanges that happen quite naturally between parents and infants. Active parent-child interactions involving an attentive parent have positive effects on the child’s development. Parents can use stories, games, joint play, illustrated books to interact with the child and these all help in the child’s development. Digital media can also be used effectively in an interactive manner with the child. This joint media attention can actually have significant positive effects on the child’s development. So, while solitary and excessive use of digital media potentially has negative effects on the child’s development, using media in an interactive manner in moderation with a parent involved may actually have some beneficial effects on the child’s development. Apart from only looking at the ST of children, it is also equally important to look at the background and adult usage of digital media. These also hinder parent-child interactions and together can be referred to as “technoference.” It therefore appears that excessive ST of children or overall technoference are proxy measures for the quality of parenting. The apparent negative effects of excessive digital medial may therefore at least partly be due to the negative effects of poor parenting practices which may be either primary or secondary to excess digital media use in the household.26,27,28 A systematic review conducted on 36 articles linking screen media and autism concluded that there is a lack of studies on the causal relationship between autism and screen usage, which further supports the view that excess digital media may be a proxy for poor parenting practices. 29
Links Between Screen Time and Attention Problems
Attention is a cognitive function which enables individuals to filter out unwanted sensory stimuli and focus or concentrate or prioritize on the important ones. 30 It also forms the portal for development of advanced cognition and determines the ability of the child to later perform better in more demanding tasks which may include executive functioning.31,32
A number of researchers have proposed that exposure to screens may reduce a child’s attention span and be linked with decreased levels of reading and concentration as compared to others.33,34,35 However, the association is likely to be more nuanced than this and depends on a number of factors. It is extremely relevant whether the young person uses the screen in an active or passive manner. 36 Older children and those with better cognitive ability are also more likely to engage with digital media in an active manner. They are more likely to play games and watch content that they themself choose. Active engagement uses top-down voluntary attentional control as compared to passive engagement that uses bottom-up information processing. Younger children are more likely to engage with their screens in a passive manner although this can vary. Early exposure in infancy therefore may have harmful effects on attention and executive function development but findings are inconclusive. Heavy cumulative exposure over years rather than current exposure is more likely to be relevant.
It is also important to assess for overall use of digital media in the household. Therefore, apart from the child’s average daily ST, household background television and parental ST should also be accounted for. A recent study found that apart from the child’s average daily ST, overall family use of digital media, maternal use of media to regulate child distress, maternal use of mobile devices while spending time with the child and exposure to multiple (rather than single) aspects of media use are all related to decreased subsequent focused attention abilities during toddlerhood. 37 It appears that excessive and injudicious use of digital media may be a proxy for poor parental practices in such households. Another study found that excessive ST at age 2 is negatively associated with the development of executive function at age 3, controlling for a range of covariates including verbal ability but again the association may be due to increased ST replacing other age appropriate activities. 38
Many researchers believe that multitasking learnt by children due to early and excessive digital exposure may interfere with the development of attentional networks and subsequent executive functioning. This makes them more vulnerable to frequent task switching and inability to sustain attention during tasks for a long time.39,40 Given the possible effects of excessive digital media on attention and cognition, it is not surprising that some researchers have found an association between excessive digital media use and ADHD symptoms.41,42 However, this is unlikely to be causal. Apart from the secondary effects of ST replacing other activities, reverse causality also needs to be considered as children with more attention difficulties simply prefer to watch more digital content.
It is important to note that moderate and judicious use of digital media in childhood doesn’t necessarily have a negative long-term association.12,30 Older children or children with better cognitive abilities may actually have certain cognitive benefits by playing video games that are goal-oriented and highly interactive. They are likely to get better at their visuospatial attention abilities and are more likely to ignore irrelevant stimuli which can have positive effects in their functioning. Some researchers argue that the early exposure and constant access to technology by today’s youth has created to a generation of “digital natives,” who have acquired a familiarity with technology and a multitasking proficiency quite unlike that of any previous generation.43,44
Conclusion
Digital technology is here to stay. As a society we have to accept that it has become an intricate part of modern living. Rather than resist it, we have to learn to use it appropriately for ourselves and our kids! The American Academy of Paediatrics 19 and a number of other bodies have advised against use of any digital media in children below the age of 2 years because of worries regarding negative effects on development. However, it appears that a large part of research and guidelines have been overly simplistic in focusing mainly on the number of hours of exposure. Although duration is important, perhaps, it is more important to focus on the quality and content of digital media. It is also important to understand that a lot of negative associations with digital media are perhaps secondary to poor parenting practices and that digital media may just be a proxy measure. Expectedly parental and background use of digital media in households have also been found to have negative association with overall early child development. ST and online activities should ideally complement offline ones rather than replace them thereby maintaining a healthy balance. And it has been seen that if digital media is used to engage the child in an interactive manner, it can be helpful for the child’s development.