Interesting Study -Detrimental Dose-Response of Screen Time

In 1995, there was a Batman movie, “Batman Forever,” in which one of the central villains, the Riddler, places these brainwave devices over the TVs to gain control of Gotham.  The sad part, according to a recent study (J Zhao et al. J Pediatr 2018; 202; 157-62) is there is no need to add a brainwave device to a TV set.  Excessive screen time alone is quite detrimental.

In this cross-sectional survey in Shanghai with more than 20,000 children, the authors found the following:

  • Mean screen time for preschool children was 2.8 hrs per day.  78.6% exceeded 1 hour per day and 53% exceeded 2 hrs per day.
  • Every additional hour of screen time was associated with increased risk for poor psychosocial well-being; this effect on well-being had a number of mediators including reducing parent-child interaction as well as increased body mass index and reduced sleep duration.

My take: This study reinforces the consequences of excessive screen time  –now, the hard part — how to translate these findings into reduction in screen time.

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Even Normal Body Mass Index Could Be a Problem

A recent study (G Twig et al. NEJM 2016; 374: 2430-40) which had more than 42 million person-years of followup (1967-2010) showed that adolescents with a BMI in the 50th to 74th percentile (CDC values), well within the accepted normal range, had increased cardiovascular and all-cause mortality.

The study involved more than 2.3 million Israeli adolescents with up to 40 years of followup information. The study utilized data obtained from 17 year olds who were seen 1 year prior to mandatory military service. There was increasing mortality associated with higher BMI subgroups.

Key findings:

  • For those between the 50-74% in adolescence: the hazard ratios for coronary heart disease 1.49, for stroke 1.18, and total cardiovascular causes was 1.32.
  • For those ≥95% (obese) in adolescence: the hazard ratios for coronary heart disease 4.89, for stroke 2.64, and total cardiovascular causes was 3.46.

My take: this study shows that even modest increases in BMI are associated with modest increase in cardiovascular mortality over 40 years.  Whether the BMI itself plays a causal role or is more of an epiphenomenon of other risk factors (eg. sedentary risk factors) is not clear.


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