his study uses a representative sample of British adolescents to assess the relationship between clinically significant psychological distress and quantitative and qualitative aspects of social network use. Overall, it replicates previous results showing a statistically significant but small relationship between mental health problems and social network use, but also reinforces the need to interpret these statistical relationships with great care.  

Before commenting on the novelties and strengths of this study it is important to note that: 

• the methodology is correlational and, therefore, does not provide evidence on the causal direction of the relationships analyzed,  
• the sample is only representative of the British adolescent population, where the evidence for a decline in adolescent mental health is stronger than in countries outside the “Anglosphere” (e.g., the EU or Latin America), 
• measures of social network use are self-reported: it is well known that these measures are unreliable when compared to objective behavioral measures, obtained from the device's own usage logs. It is quite possible that people with alterations in their mental health have a more distorted perception of their use of social networks or “screens” in general.  

That said, this is a registered report (RR), a type of study in which all the hypotheses, methodology, and data analysis strategy are sent to the journal for review before the data are collected. Once the first part of the RR is accepted by the journal, the data are collected and analyzed following as scrupulously as possible the plan drawn up and accepted beforehand. This guarantees that the hypotheses are not altered (HARKing), nor are the analyses made more flexible (p-hacking), or the measures selected a posteriori (data slicing/cherry picking), so that the results are more attractive or in line with the interests of the researchers. In addition, the study is carried out collaboratively by two of the most prestigious and methodologically reliable groups in the world today (at Oxford and Cambridge Universities). It is especially noteworthy that, although Amy Orben and Andrew Przybylski have collaborated closely in the past, their positions have diverged in recent years and that the collaboration between the two ensures a diversity of perspectives that reduces the possibility of interpretative bias.  

With respect to the results, the main novelties are the following: 

• We replicate the statistically significant but weak relationships between measures of mental health and measures of social network use in adolescents, with the novelty that the mental health measures used allow us to distinguish between participants who suffer some clinically significant psychological disturbance and those who do not, using clinically valid interview methods and not just self-report screening, as in most available studies.  
• A distinction is made between people suffering from internalizing (e.g., anxiety or mood disorder) and internalizing (e.g., ADHD or conduct problems) disorders and they are compared both with each other and with the group without psychological disorders. Most interestingly, although both the internalizing and externalizing groups show an increase in the use of social networks, only the internalizing group shows differences in qualitative indicators. More specifically, adolescents with internalizing problems showed increased social comparison, greater influence of social network feedback on their mood, lower satisfaction with the number of online friends, lower honest self-presentation, and lower perceived control over social network use compared to those without a mental health disturbance. None of these qualitative effects were noteworthy in the externalizing impairment group. As a note, this difference is important because addictions are considered externalizing disorders. The absence of signs of problematic social network use among people with externalizing disorders would indicate an important difference between problematic social network use and addictive disorders in the strict sense, such as substance addictions or gambling disorder. On the other hand, they would reinforce the increasingly widespread idea that problematic social network use is only a part of more general problematic behavior patterns related to the context and the social and family life of the individual, and in which previous emotional problems are an important vulnerability factor.  
• Although the results do not provide causal evidence, they do reveal some possible mechanisms of the interrelationship between mental health and social network use. More specifically, they are compatible with an interactionist model in which emotional and mood disturbances would induce social network use (e.g., disadvantageous social comparisons) which, in turn, would lead to poorer mood. In that model, it is emphasized that risk and protective factors in the online context are not too different from those appearing offline. For example, the tendency to disadvantageous comparison would not be exclusively in networks, but also outside networks, just as the quality of online friendships would exert a protective factor in the online context similar to that exerted offline. Although it is true that the ubiquity and accessibility of the Internet may be a risk factor for entering into these feedback loops, it is also true that its prevention would involve promoting a more rewarding use and a greater degree of social protection in the network. 

My main concern with this paper is that it gives the impression that the adolescents had been diagnosed beforehand by a healthcare professional, and possibly receiving mental health support: this is not the case.

While the research itself generally looks to be of good quality, the lack of direct input from young people is disappointing. The study places a particular emphasis on the negative aspects of social media use, but from our own work with Youth Advisors from the charity Young Minds, we found that there are positives too, including giving them a sense of community and in some cases reducing feelings of isolation.

Digital technology and social media have become an integral part of adolescents’ lives. While I recognise the negative effects that social media can have, society needs to find ways to harness it safely and in a way that enhances mental health.