Attention-deficit hyperactivity disorder in children is related to maternal screen time during early childhood in Taiwan: a national prospective cohort study

Our results revealed that mothers’ screen time when children were aged 3 years was positively associated with the incidence of ADHD in children by the age of 8 years. Notably, the role of children’s and fathers’ screen time in the rate of ADHD during early childhood appears to be limited.

In our study, we observed a parent-reported community diagnoses of ADHD prevalence of 2.3% in 8-year-old participants in 2013. This prevalence is considerably lower than that of 6.3% in students aged 6 to 9 years reported in a field study conducted by a group including psychiatrists [19]. The low prevalence rates observed in this study, as determined through community diagnoses, may potentially be lower than epidemiological estimates derived from comprehensive mental health assessments, indicating a potential underdiagnosis However, our observed prevalence is similar to that reported in a study using Taiwan’s National Health Insurance Research Database (NHIRD), which covered 99.9% population in Taiwan; this study indicated that 2.23% of children aged from 7 to 12 years underwent medical assessment and treatment for ADHD in 2011 [20]. Moreover, according to the NHIRD, the prevalence of ADHD in male youth was approximately 4 times higher than that in female youth; this finding is consistent with that of our study population. Thus, children with ADHD in our study may reasonably represent those diagnosed with ADHD in medical settings.

Screen time refers to the time spent watching television, playing a video game, or using an electronic device with a screen (such as a computer, smartphone or tablet). The WHO defines it as “time spent passively watching screen-based entertainment (television, computer, and mobile devices), and it does not include active screen-based games where physical activity or movement is required.” During 2005 to 2008 when the TBCS was conducted and data on screen time were collected, the research sample was less than 3 years old. Taiwanese families then did not use mobile electronic devices, such as smartphones and tablets, on a daily basis. Although the iPhone was first launched in 2007, it was not officially available in Taiwan for purchase until the end of 2008. The iPad was launched in 2010. Therefore, at that time, toddlers younger than 3 years mainly watched television, videotapes, DVDs, and some computers. The average exposure time was 1 h and 45 min in 18-month-old children and 2 h 42 min in 3-year-old children. This screen time of 3-year-old children is similar to that of more than 2 h per day, including computers, communication, and consumer electronics, determined from KIT in 2013 to 2014 [14]. The global average prevalence in children aged 2 to 5 years who met screen time guidelines (1 h per day) was 35.6% [21], and in our participants, it was approximately one-quarter. A positive correlation was noted between children’s and parents’ screen time, which is consistent with the findings of a previous study in preschool children [22]. In recent years, with changes in the social atmosphere, the habit of using screen electronic devices has become increasingly common. In addition, during the COVID-19 pandemic, an estimated 66 more minutes of screen time per day have increased among preschoolers aged less 5 years and an additional hour per day among adults aged over 18 years [23, 24]. Further research is warranted to determine the effects of such changes on health.

Studies have reported a relationship between screen time, including television viewing, game playing, video watching, and computer using, and ADHD symptoms or behaviors and externalizing behaviors [9, 10, 25]. In Taiwan, prolonged touch screen device usage was found to be associated with attention problems and aggressive behaviors in toddlers aged from 18 to 36 months [26]. However, despite the increasing number of cohort studies focusing on the relationship between preschool exposure to screen and the incidence of ADHD diagnosis, this association remains inconclusive. A Dutch cohort study determined that screen time, with an average of 29.4 min per day for 2-year-old children and 58.3 min per day for 4- to 5-year-old children, was cross-sectionally related to externalizing symptoms during early childhood but not associated with the diagnosis of ADHD at the age of 8 to 10 years [27]. The possible explanation is that screen exposure affects short-term behaviors without exerting sustaining effects. In addition, variations in the amount, frequency, content, and types of media of screen exposure may account for the elusive long-term adverse health effects. Few studies have examined the effects of children’s screen time on ADHD while considering mothers’ screen time. A study on German children using a cross-sectional approach determined that higher maternal screen time was significantly associated with children’s higher screen time, and both were associated with ADHD symptoms among 2- to 9-year-old children [28]. Our findings partially fail to indicate the association between children’s screen time and ADHD risk, which may be attributable to differences in the study methodology and the definition of dependent variables. Because of the small number of studies and inconsistent evidence, more research is warranted.

The Differential Susceptibility to Media Effects Model (DSMM) is a theory in media studies that suggests individuals vary in their susceptibility or responsiveness to media messages and content [29]. This model posits that people have different levels of vulnerability to media influences based on factors such as their personality traits, demographics, and life experiences. Some individuals may be more susceptible to the effects of media, while others are less so. The DSMM can also theoretically interpret the effect of media usage on ADHD-related behaviors [30]. The most explanatory hypotheses state that children’s media-evoked responses following the fast pace or violent nature of media increase the likelihood of ADHD-related behaviors. To confirm this, we did exam the content of media. Exposing children to violent but not erotic content may also be linked to further ADHD diagnoses. (Supplementary Table 3) In terms of developmental and dispositional susceptibility, we did evaluate media exposure among young children and investigated sex differences in susceptibility, showing significant outcomes for mothers’ screen exposure among boys (Supplementary Table 2).

We assumed that the adverse effect of longer exposure among mothers during early childhood fits the social susceptibility hypothesis in the DSMM, such as parenting style and media-specific parenting. As demonstrated in Supplementary Table 2, mothers were the most commonly identified primary caregivers among the study participants. In addition, we had information on how often mothers watch TV with their children at the age of 36 months. However, all answers were “always” and no further information was given. Parenting style is a factor for ADHD-related behaviors [31]. Parenting style, demographic factors, and parental well-being amplify the effects of children’s media use on ADHD-related behaviors [32, 33]. A study examining the effects of television on the interaction between parents and children aged under 3 years determined that when the television was on, the quality and quantity of parent–child interaction decreased compared with when it was off [34]. In 2009 in Taiwan, one of the family pastimes that preschool students participated in the most was watching television, including videotapes, although it does not contribute to the establishment of parent–child interaction [35, 36]. Nevertheless, a German study reported that children’s and mothers’ media use and parent–child interaction independently contribute to ADHD behaviors [28]. The correlation of screen time between the two is expected because when one person is watching a television or videotape, the other is also watching. Thus, parent-reported screen time may underestimate the screen time of some children who watched TV along with their parents. Furthermore, the amount of screen time may reflect parenting styles, parent–child interaction, or other intrinsic biopsychosocial factors in parents instead of environmental exposure per se. This study found that the lack of significant correlation between paternal screen time and ADHD diagnosis, which could also be interpreted since the majority of children were cared for by mothers. We believe that the manner or method of companionship is very important, because some companionship may just be with them without any guidance or education, and some are not. However, we cannot precisely break down the total time watched together or individually, and it would be inappropriate to overinterpret the current information. The content of the media and why and how these electronic devices are used are crucial. Thus, the current evidence should be confirmed in future studies on the long-term effects of screen time on ADHD.

The strength of this study is that it provides new insights into the relationship between early childhood screen time among children and mothers and ADHD onset. The study benefited from a representative sample of Taiwanese infants born in 2005 with a population-based cohort design that responded well to detailed data on covariates. Furthermore, the independent variable was collected when children were aged 18 and 36 months, which minimized recall bias for the target dependent disease or symptom collected years later. A limitation of the current study is that ADHD and screen time were assessed on the basis of parental reports, which may have contributed to reporting bias. The prevalence of this diagnosis is similar to that in the same age group in Taiwan’s NHIRD. Thus, our sample of children with ADHD is likely representative of the community-based population. That said, self-reactive overdiagnosis was unlikely to occur in our study sample. Despite concerns regarding the underdiagnosis of ADHD, ADHD diagnosed by the age of 8 years might reasonably represent a proportion of more severe cases, and some children with ADHD may be observed in subsequent years. The study may be, therefore, biased toward children with more severe ADHD symptoms. Moreover, exact data on the amount of screen time and the time children spent gazing at the screen were not available. Information on pattern, such as continuous exposure and interval rest periods, or parenting factors while watching television/videotapes were not available in our dataset. Thus, the variation in these parameters cannot be explored in the current study. Obtaining such information would have been impractical in a large cohort study conducted more than 10 years ago. People are likely to underestimate the amount of TV they or their children watch, especially those with more screen time. In theory, this misclassification might reduce the observed association. Nonetheless, the observation of a significant relationship between maternal screen time and ADHD diagnoses suggests that the actual effect may be stronger. Additionally, 8% of survey participants were not followed up when their child was approximately 8 years old and did not provide a reason for the refusal. Therefore, whether rejection is associated with clinical features related to ADHD remains unclear. Overall, the impact of bias is acceptable because of the high participation rate.

Nowadays, we are expecting to see improvements in measurement and inspection equipment to more accurately assess screen viewing, for example, using portable devices and identifying the wavelength and brightness of screen light sources. Besides, different forms of screens, content, whether there is parental guidance to watch, watching TV alone or with adults, etc. are all aspects worthy of further research and exploration. Moreover, the causes and mechanisms behind screen time that cause health problems need to be further clarified. Nevertheless, long-term health effects, dosage effects, recommendations for appropriately limiting screen time or duration per session, appropriate timing of viewing (e.g. while eating, waiting, in bed) all require research for further clinical application. Last but not the least, with the proliferation of smartphones, tablets, and other multifunctional devices in our daily lives, detailed information on screen exposure should be captured in the near future.