Screen time in preschool-aged children and attention deficit hyperactivity disorder-related behaviors: A literature review

Abstract

In this digital era, excessive screen usage has been reported to worsen the symptoms of attention deficit hyperactivity disorder (ADHD) in children. However, this connection is found to be bidirectional, with both phenomena impacting each other. The current literature review will summarize some research findings on the correlation between screen time and ADHD-related behaviors. Studies have found that the inattentional and hyperactive/impulsive behaviors of ADHD are positively correlated with screen time. One study showed statistically significant longitudinal correlations between screen time at age three and inattention behaviors and hyperactivity/impulsivity behaviors at age four, but no concurrent association between screen time and either of these behaviors or scores at age three. Crucially, screen usage beyond the two-hours mark was linked to a higher risk of externalizing morbidity that is clinically significant, particularly inattention issues. Meanwhile, screen usage can exacerbate the symptoms of ADHD in children, including aggression, negative emotions, and pressure from life events, according to a summary of pertinent studies.

Key Words: Attention deficit hyperactivity disorder; Behavioral problem; Inattention; Impulsivity; Pediatric; Screen time

Core Tip: Screen time has long been believed to cause many behavioral problems in children, particularly in the form of autism or attention deficit hyperactivity disorder (ADHD). However, the correlation is not unidirectional but bidirectional. In ADHD cases, screen time may be a promoting factor for ADHD development; however, subjects with ADHD also have a tendency to spend more time in front of the screen since it is associated with the instantaneous reward provided by the screen, particularly in video games. This review discusses the bidirectional nature of screen time and ADHD along with several mechanisms underlying this correlation.

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder characterized by several core symptoms, including inattention, hyperactivity, and impulsivity. Its prevalence varies widely across the globe, and it is estimated that 7.6% of children aged 3 to 12 years and 5.6% of teenagers aged 12 to 18 years develop ADHD[1]. Subjects with ADHD frequently face significant issues regarding their learning, social interaction, and emotional regulation abilities[2,3]. Furthermore, ADHD is regarded as a key contributor to the global burden of disease in children and adolescents[3,4]. It also imposes a significantly higher cost on parents to raise a child with ADHD than those without such disorder, with a previous study cited that it could cost five times more than raising children without ADHD, primarily being driven by the indirect costs associated with parents losing their jobs or missing workdays[5].

Although the exact pathophysiology of ADHD is not fully understood, environmental factors including lifestyle factors are recognized to play an important role in its development[6]. Among these factors, the relationship between screen time and ADHD risk has become a prominent topic of research in recent years. Moreover, it resembles a vicious cycle, where screen time can be both a promoting factor for and a consequence of ADHD[7,8].

In recent years, the widespread adoption of electronic devices has significantly increased children’s screen time. Furthermore, this exposure is occurring at progressively younger ages, raising widespread public concerns about the impact of electronic screens on children’s mental health[9]. Despite the World Health Organization's (WHO) guidelines[10] regarding the developmental needs of young children—specifying a maximum of one hour of screen time per day (with the supervision of a parent or guardian) for those aged 2 to < 5 years and no screen exposure for those under 2-there a troubling trend emerges: A significant majority of preschool-aged children consistently surpass the recommended screen time limits. Specifically, only 24.7% of children under 2 years adhered to the guideline of avoiding screen use, while 35.6% of children aged 2 to < 5 years complied with the screen time limitations[11].

Screen time refers to the time a person spends using electronic or digital media devices such as television, smartphone, tablet or computer. There is a rising concern that children who use screens excessively may experience cognitive and psychological problems. The inherent connection between screen time and ADHD in children is still up for discussion, though. According to reviews, there is a high correlation between screen time and ADHD or traits associated with ADHD, like impulsivity and inattention[12,13]. As research deepens, it is becoming increasingly clear that, in addition to the total amount of screen time, the type of screen content also has a significant impact on children’s psychological development. For example, educational and cartoon videos have a significant association with ADHD development, while interactive videos do not show similar tendencies[8].

This literature review will investigate the relationship between preschool children's screen time and symptoms of ADHD. This manuscript will give a comprehensive discussion on this topic and present the potential bidirectional association between screen time and ADHD-related behaviors.

SCREEN TIME CLASSIFICATION

Screen time can be classified into two main categories based on its exposure, active and passive screen time. Active screen time usually requires a higher level of cognitive engagement and response from the child, including playing video games, video chatting, utilizing educational apps, and using a computer. Meanwhile, passive screen time is a situation in which participants are only consuming the screen-based information without significant interaction or cognitive processing, such as when they are watching the television, video, or film[14]. It tends to lead children developing a much higher sedentary lifestyle compared to active screen time, particularly since in the recent years, video games that require physical activity have grown in popularity, such as the XBOX Kinect^TM, Sony PlayStation Move^TM, and Nintendo Wii^TM[15].

A study determined that while passive viewing of both educational and cartoon videos was highly linked with an elevated ADHD risk in a dose-response manner, the utilization of interactive videos presented no relationship with ADHD risk across any duration category[8]. This can be explained by the “video deficit hypothesis”, which states that toddlers under the age of three exhibit greater difficulty developing their language and cognitive abilities via two-dimensional displays than from real-life, three-dimensional communications with caregivers[16]. This difficulty is due to the absence of substantial interpersonal signals, such as collaborative engagement and responsive input, which are essential for early childhood development.

Besides the screen exposure approach, the content of screen material is crucial. Parents frequently rationalize screen time by choosing information advertised as educational, perceiving it as advantageous or, at the very least, harmless[17]. Nevertheless, the research conducted by Wu et al[8] revealed that these "educational videos" exhibited a dose-response risk of ADHD symptoms that was equally potent, if not more so, than that associated with amusement cartoons. This evidence suggests that the structural attributes of the content, not the label itself, primarily determine the developmental influence. This argument contests a prevalent parental rationale for permitting screen time[18]. Some characteristics, including accelerated pacing, frequent scene transitions, and a relentless influx of powerful visual and auditory stimuli, are thought to overwhelm a child's growing attentional capabilities[19]. This observation corresponds with the “scan and shift” hypothesis, which posits that such media conditions the brain for quick attentional shifting and distraction instead of fostering sustained, focused attention[20]. Moreover, content lacking a clear narrative framework or featuring fanciful elements may place a greater cognitive burden on a young child[21], requiring additional mental resources for processing and comprehension. Research has shown that when children watch a wider variety of programs, like cartoons, games, and movies, it is linked to more severe ADHD symptoms, suggesting that consuming different types of exciting content adds up to a bigger effect[22].

SCREEN TIME DURATION GUIDELINES

Children between the ages of two and five are advised to have minimal screen time, in part because it is assumed that screen time reduces time for imaginative and energetic outside play[23,24]. In addition, excessive screen time is found to have a significant impact on children’s well-being, including mental health issues and physical activity limitations. An investigation from China reveals that screen time is strongly associated with mental health issues after controlling for confounding variables and is mitigated by improved physical activity among preschoolers[23]. A German study indicated that students who used screens for two hours or more were more likely to attain unsatisfactory academic performance. Individuals who failed to adhere to both requirements for exercise and screen time exhibited a higher prevalence of overweight or obesity and obtained less sleep than the recommended duration[25]. The WHO and the American Academy of Pediatrics have equivalent guidelines for screen time restrictions for children, recommending no screen exposure for those under 24 months and a maximum of one hour of screen time for individuals aged two to five years[10,26]. The objective is to provide children sufficient time to participate in activities vital for their health and development while fostering media consumption habits linked to a lower likelihood of obesity in the future[27]. Preschoolers are advised to engage in a minimum of 180 minutes of diverse physical activities of any intensity, including at least 60 minutes of moderate- to high-intensity physical activity. Meanwhile, during sedentary screen time, children should engage in storytelling and reading with a caregiver. Furthermore, they must obtain adequate sleep duration to preserve their overall health[10].

SCREEN TIME EXPOSURE AND ADHD-RELATED BEHAVIORS: A CORRELATIONAL LINK

A significant volume of observational studies provides convincing proof of a positive, dose-response relationship between screen usage and the frequency and intensity of ADHD-related behaviors in young children. A study demonstrated a statistically substantial longitudinal association between screen time at a baseline age (about 3.6 years) and inattention (β = 0.27) and hyperactivity/impulsivity (β = 0.32) one year after the observation, even after statistically controlling for the children's initial symptom levels[28]. A study from The Canadian Healthy Infant Longitudinal Development project found that preschoolers (under five years) who spent more than two hours a day on screens were 7.7 times more likely to meet the criteria for ADHD according to the Child Behavior Checklist, a well-validated, parent-reported tool. That study also presented that the most common modalities of screen exposure were televisions (98.2%) and mobile phones (87.3%)[29]. Additionally, a study by Hill et al[30] found that the amount of screen time measured at 18 months was a strong indicator of ADHD symptom severity as reported by parents and lower developmental achievement by ages 3-5 years. Furthermore, a secondary analysis from the 2018 to 2020 National Survey of Children’s Health in the United States[31] indicates that children who engage in four or more hours of daily screen usage are 1.85 times more likely to be recognized as having ADHD than those who use screens for less than one hour per day, particularly for boys and toddlers. Additionally, after adjusting for confounders, children who use screens for three or more hours daily are 1.16 to 1.32 times more likely to exhibit ADHD, respectively. It demonstrated a substantial dose-response link between screen time duration and the likelihood of neurodevelopmental and behavioral issues.

Some of the findings also originate from cross-sectional research, which showed children with ADHD or an elevated occurrence of ADHD-related symptoms devote considerably longer periods in front of screens than their typically developing peers. Nevertheless, the association goes in both directions, so screen time and ADHD can influence each other. For example, Vaidyanathan et al[32] undertook a study in South India with toddlers who had ADHD. They found that 80.4% of the participants spent more time than the advised hour of screen time every day. Individuals with ADHD devoted a mean of 140 minutes a day on screens, and the more time they spent on screens, the worse their symptoms became, according to the Conner's Abbreviated Rating Scale (r = 0.29). This behavior may be driven by a need to meet their reward sensitivity needs, although it could further worsen ADHD symptoms since screen-based activities may reduce children’s motor functions and kinesthetic senses[7,33].

Meanwhile, large studies of Chinese preschoolers have revealed strong connections between ADHD and screen time, where those who spend more than sixty minutes daily on screens are more likely to demonstrate ADHD manifestations (odds ratio = 1.826). This finding is also significant in families with multiple offspring[34]. Moreover, a cross-sectional study involving more than 42800 Chinese children aged < 3 years found that children who spend more than 90, 120, 150, and 180 minutes a day in front of a screen are 1.98, 2.71, and 4.62 times more likely to be hyperactive than children who spend less than 90 minutes a day in front of a screen[35].

Meta-analyses, which aggregate data from various research to produce a more precise and trustworthy estimate of the effect, also substantiate the findings between screen usage and ADHD. A meta-analysis by Beyens et al[36] examined four decades of studies (from the late 1970s) and found a statistically substantial connection between screen media usage and ADHD-related behaviors. A more recent meta-analysis by Liu et al[37], which looked at nine studies involving over 81000 children (almost 29000 children with ADHD), found that children who spend more than two hours a day on screens have a 1.51 times higher risk of developing ADHD compared to those who use screens less than two hours daily.

Screen usage was more connected with behavioral morbidity than any other risk factors, including socioeconomic status, parental stress, and sleep duration[29]. Excessive screen use in preschool children will also markedly affect their social abilities[24] by diminishing peer involvement, thereby impairing socialization and the development of normative social skills, including psychological well-being. On the contrary, outdoor play as a proxy for physical exercise, along with better sleep maintenance, may help to reduce ADHD symptoms[38,39].

A major discovery is the fact that the dose-response relationship between screen time and ADHD remains consistently observed across various cultural and socioeconomic contexts[30,36,40]. If the association were solely attributable to a variable prevalent in a single culture, such as a specific parenting style typical in Western nations, it would be improbable for it to exhibit such strength across diverse contexts. The persistence of this link indicates that the screen time and ADHD association reflects fundamental and universal mechanisms[41]. The association may result from the inherent responses of the developing human brain to rapid visual and auditory stimuli, or it may stem from the universal implications of the displacement hypothesis, which suggests that screen time supplants essential developmental activities, such as play and social interaction, irrespective of cultural context[42,43]. This cross-cultural influence significantly strengthens the argument for examining the biological and psychosocial pathways addressed in subsequent sections of this analysis.

MECHANISMS BEHIND SCREEN TIME-ADHD ASSOCIATION

There are multiple potential mechanisms underlying the screen time and ADHD correlation (Figure 1). The differential susceptibility to media effects model asserts that emotional, cognitive, and excitative responses following media exposure can determine the impact of screen usage[36]. These processes directly affect the brain's ability to focus and manage tasks, and they also indirectly change important developmental activities, which manifest as a key sign of ADHD. A recent study indicated that impaired executive function significantly contributes to the association between excessive screen time and behavioral challenges in preschoolers, including their self-regulation abilities[44]. Another longitudinal research study of adolescents over five years revealed that increased social media usage was a predictor of heightened self-reported impulsivity, which subsequently forecasted an increase in ADHD symptoms[28]. A further study indicated that television viewing at age two correlated with diminished emotional and motivational control-related executive function, whereas television viewing during meals at age four was associated with impaired cognitive-related executive function[45].

Figure 1 Screen time and attention deficit hyperactivity disorder-related behaviors correlation. PFC: Prefrontal cortex; ADHD: Attention deficit hyperactivity disorder.

From a neuroscience perspective, neuroimaging studies indicate that behavioral changes are likely biological in nature, particularly regarding how screen usage may affect brain function and appearance. Wu et al[46] conducted a comprehensive scoping review demonstrating that early electronic usage can alter the parietal, temporal, frontal, and occipital lobes. The prefrontal cortex, responsible for higher-order activities, appears to be the most impacted by these alterations. The arousal-habituation hypothesis effectively elucidates the connection between screen time and ADHD. It asserts that violent and fast-paced media increases physiological arousal, but over time, the baseline arousal level of adolescents diminished[22,36]. Research using Diffusion Tensor Imaging has demonstrated that children with prolonged screen time exhibit compromised integrity in the brain's white matter tracts essential for language and executive function, which was mentioned earlier as a hallmark of ADHD[7]. Moreover, evidence indicates that excessive screen time modifies the brain's dopamine system. A positron emission tomography scan indicated that individuals who often utilized social media experienced reduced in dopamine production. This phenomenon resembles the notion that individuals with ADHD possess insufficient dopamine levels[47]. Prolonged digital stimulation may result in acquired dopamine dysregulation. In preschool children, whose brains are undergoing swift maturation of executive functions, this effect may be particularly substantial for their overall brain function[48]. This may indicate that their brains can endure rapid transitions in focusing on various auditory and visual stimuli; however, it may alter the neurological development of children, potentially resulting in manifestations of ADHD in the future. Evidence indicates that screen usage gradually alters the duration of the attention span in preschoolers[49].

The displacement theory proposes that screen time significantly influences the brain and cognition indirectly, alongside its direct impacts. This perspective asserts that the primary issue with screen time is not the exposure itself, but rather the deprivation of enjoyable, real-world activities that are beneficial for healthy development[8,35]. One of the most significant issues is the impact of screen usage, which directly diminishes the quantity and quality of interactions between parents and children[50]. A survey conducted in the United States revealed that children with ADHD were less inclined to participate in sports and engage in daily physical activity[51]. Finally, a distinct correlation exists between screen usage and sleep disturbances. Watching screens, particularly before resting for the night, may impede children's ability to fall asleep and may result in a shorter sleep duration[52]. This phenomenon can be attributed to two main factors: (1) The blue light emitted by screens inhibits melatonin production, the hormone regulating sleep-wake cycles, and (2) The stimulating content engages the child both physically and mentally, hindering relaxation[53]. This sleep disruption significantly impairs concentration, emotional regulation, and executive skills, all of which are closely associated with and exacerbate the primary symptoms of ADHD[54].

Another rationale for this relationship is the mendelian randomization investigation, which identified evidence for a causative "media effect". This indicates that those with a genetic predisposition to increased screen usage are also more prone to receiving an ADHD diagnosis[7,55]. On the other hand, studies using polygenic risk scores have shown strong evidence of a "selection effect", meaning that people who are more genetically likely to have ADHD tend to spend more time on screens[7,56]. These effects will be discussed in more detail in the following paragraph.

None of the described mechanisms operate in isolation; rather, they collaborate to establish a negative feedback loop that impedes neurodevelopment, which can be challenging to interrupt. The relationship between screen time and ADHD can be elucidated through two distinct mechanisms: Selection effects and media effects[36]. Selection effects correspond to the notion that children with preexisting temperamental or neurological issues that predispose them to ADHD are more likely to seek out and engage extensively with screens[20,30,36]. Children exhibiting high impulsivity, difficulties with self-regulation, and a preference for high-stimulation, low-effort pursuits may find the immediate rewards and rapid pace of various screen media particularly attractive[20,30,57]. Conversely, media effects denote the concept that exposure to screens may exacerbate ADHD symptoms or precipitate their onset via the neurocognitive and psychosocial pathways[36,58] outlined in the preceding section. This pathway indicates that screen time is an influential component of the environment that impacts individual growth and development[59]. Although screen time can result in transient behavioral issues, these issues do not necessarily culminate in a long-term, diagnosable disorder. This model illustrates the need to distinguish between transient behavioral issues and persistent medical conditions[55].

In addition to the previously indicated mechanisms, numerous other factors are associated with screen time usage and heightened sensitivity to the adverse impacts of its utilization. These can be categorized using a bioecological framework that depicts their impact on individuals, society, and culture[60]. Research indicates that children with a familial predisposition to ADHD engage with screens for extended periods at an earlier age. Due to their atypical neurodevelopmental trajectories, these individuals may be more impacted than their peers[30,61,62]. Hill et al[30] conducted a longitudinal study and found that 94% of children with ADHD had frequent screen time at 18 months of age. This percentage was significantly greater than the 72% of youngsters in the control group. This data suggests a similar screen time period may have a more pronounced effect on the brains of children undergoing atypical development, as these children already struggle with self-regulation, interpersonal communication, and sustaining attention[63].

Parental stress and mental health emerged as significant determinants influencing family dynamics. A direct correlation exists between elevated parental stress levels and increased screen use among children. Parents may resort to screens to manage undesirable behavior or to alleviate their own challenges[64]. A longitudinal study conducted by Almeida et al[62] during the coronavirus disease 2019 pandemic revealed that children who engaged in prolonged screen time and parents experiencing heightened stress at 3.5 years of age were more predisposed to exhibit indicators of inattention one year later. This finding indicates that parental stress is a significant environmental factor that may exacerbate behavioral risks associated with screen usage. Parental stress may adversely impact children's outcomes by limiting their access to adequate stimulation and environmental enrichment. This may result in diminished adherence to medical treatment, insufficient parental involvement, and a shortage of motivation for behavioral therapies. Furthermore, the presence of screen devices in a child's bedroom is a significant environmental factor associated with increased screen time and adverse outcomes[59,65]. Researchers examined Singaporean toddlers with neurodevelopmental abnormalities and discovered that an increased presence of screens in the bedroom correlated with heightened sleep disturbances, which were associated with more significant emotional and behavioral issues[65].

CONCLUSION

Screen usage can exacerbate the symptoms of ADHD in preschool children, including aggression, negative emotions, and pressure from life events, according to a summary of pertinent studies. Additionally, it might harm the family environment and impede language development in subjects with ADHD. The association between screen time and ADHD is bidirectional, and can be explained with selection and media effects. Most importantly, it is recommended to strictly follow WHO guidelines regarding screen usage and participate more in physical activity, particularly among preschoolers, since it can help to reduce ADHD-related behaviors while preserving children's overall well-being.