Screen time increasing in kids, and new literature review

The American Heart Association Obesity Committee of the Council on Lifestyle and Cardiometabolic Health just provided an updated perspective on sedentary behaviors (and particularly screen time), with recommendations on the prevention and management of childhood obesity (see obesity inc screen time in kids AHAadvisory2018 in dropbox, or https://www.ahajournals.org/doi/pdf/10.1161/CIR.0000000000000591 ). In particular children 8 to 18 spend on average more than 7 hours daily on screens for recreational purposes.

Details:

-- a 2012 review of prospective studies found that physical inactivity was the 4^th highest risk factor for mortality worldwide, and is associated with excess morbidity and mortality in adults

-- physical inactivity reflects a low involvement in activity, whereas sedentary behaviors reflect being seated with low energy expenditure, as per television watching, reading, and motorized transport

-- prior data supports the association between recreational television viewing time, video games, DVDs, and computer use with childhood adiposity. This report includes the more updated/relevant “screen-based media landscape”

-- screen time was defined as “watching TV and time spent using the computer or other screen-based devices such as tablets and smart phones to view television content, watch movies and videos, browse the Internet, spend time on social media, and play video games”

Results:

-- though access differs by income, overall 7 in 10 adolescents own a smartphone and use it an average of 4.5 hours daily, excluding talking and texting, per the Common Sense Media

-- the average of the time spent on recreational screen-based media among 13 to 18-year-olds is 6 hours 40 minutes, of which 2.5 hours were on TV

-- school-age children are sedentary for about 8 hours of their daily waking hours

-- screen time increases substantially with age, notably during preadolescence; adolescents are the most sedentary of the pediatric population, engaging in the most total recreational screen-based activities

-- traditional television watching has declined in the past 10 years

-- lower social economic status is associated with more hours of television viewing but not computer or video game-based screen time

-- other associations with more sedentary time:

    -- less outdoor play, including by parental restriction, in girls

    -- maternal television watching, in girls

    -- maternal depression or distress and less cognitive stimulation in the home environment, in younger children

    -- the number of televisions and computer games or game consoles in the household

    -- fewer family rules about television viewing

    -- infrequent family meals

    -- having a television in the bedroom (which also can disrupt sleep leading to later sleep onset and shorter duration, with its attendant sequelae of school performance, for example)

    -- greater distance to green spaces and less walking infrastructure in the neighborhood

    -- perception of less neighborhood safety and crime rates

-- sedentary behavior and adiposity/cardiometabolic health:

    -- more time spent in sedentary behavior in adolescence was associated with adiposity, high triglycerides, and metabolic syndrome. The data were less clear in the younger pediatric population, and the data are also less clear with objectively measured sedentary behavior

    -- there may be bi-directionality: sedentary behavior may lead to weight gain, but weight gain may also be associated with increased television watching

    -- overall, screen time is associated with adiposity, and this is often true after controlling for diet and physical activity (including moderate to vigorous activity)

interventions:

    -- in preschool children, several interventions led to decreases in screen time of about 20 minutes, most successfully in younger children

    -- most successful interventions involve greater parental involvement and structural changes (eg ,moving the TVs from the bedrooms) in the home environment, with more parental involvement being the key determinant regardless of the setting of the intervention (home, community, school, primary-care based)

    -- electronic television monitoring devices seem to be effective in reducing sedentary behavior

    -- both family-based and school-based interventions may be more successful in youth with normal weight than those who are overweight or obese

Commentary:

-- much of the data is self-reported, though they comment that in the pediatric population, self-reported sedentary behavior is generally reliable. Some studies also used accelerometers, inclinometers, wearable cameras, and direct observation.

-- It should be noted that the actual physiologic damage of sedentary lifestyle found in adults is not found in kids

-- BUT, obesity in kids (associated with sedentary lifestyles, as above) does track to adulthood. and there are several large longitudinal studies (eg Nurses' Health Study) finding that obesity in adolescence is associated with premature death in adulthood, even independent of adulthood obesity

-- most studies used the two-hour threshold of screen time, though some studies have found that even one hour appears to be detrimental

-- for unclear reasons they do not make recommendations on the optimal limit of screen time but do note that per the 2009-10 NHANES report, 46% of elementary school children to exceeded the recommended <2 hours per day

-- pretty clearly, one of the major issues here is the lack of effective strategies in adolescents. Which raises both the need for more aggressive interventions at a much earlier age (current interventions more effective then), as well as the need for better interventions in older kids

-- unfortunately, several of the risk factors for childhood obesity really parallel the increased social isolation and lack of family cohesion so present in current American society: the infrequent family meals, distress/depression in parents, decreased outdoor play time (though with the sometimes overstated fears of having kids play outside), higher access to screens at home and elsewhere (leading to the oft-cited observation of families out at dinner, with each member watching their phones, texting, etc, and not really interacting), etc

so, this is an increasingly important issue in our society (and most Western ones, increasingly so in lower-income countries as well...). There are pretty clear short-term and long-term medical sequelae to sedentery lifestyles/obesity. And behavioral changes need to be addressed very early and not wait until school age or (especially) adolescence. But, perhaps the main long-term issue here is a social one: 

    --this increased use of readily accessible screens does reflect the high-tech age we live in and is reinforced by its seductiveness

    --but, the increased use of these devices additionally reflects and also reinforces the increasing social isolation of people in our society, including social anomie, the breakdown of social standards and structures.

The solution to this problem is fundamentally a social one, one that cannot be treated with drugs. we as a society need to deal with the underlying factors leading to this social isolation and the barriers for kids to have healthier lifestyles of good diet and exercise, which include such items as decreasing accessibility to unhealthy foods and increasing the focus on healthy ones, increasing the access to and strongly promoting adequate exercise, providing social structures to support family well-being and cohesion, etc. As per Virchow in 1879 (and mentioned a couple of days ago): "Don't crowd diseases (epidemics) point everywhere to deficiencies of society?"

geoff​

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