**1. Introduction**

The creation of social groups to exchange information, share experiences, or provide support is a natural human impulse [1]. The growth of the internet has led to new channels for social networking, which have evolved and adapted to meet the needs and resources of the population [2].

In the digital era, online social networks have become a central node through which individuals connect and interact with other people [3], by sharing, viewing, or commenting on ideas and content posted by other users [4,5]. The use of social media has exponentially escalated since the late 1990s. The dynamic nature of these platforms has been the reason for their rapid growth, and the structure of

these media has facilitated the creation of relationships among users [6,7]. Although individuals often use these networks to meet new people, there is a tendency to connect with those who hold similar expectations or preferences [8].

Additionally, one of the reasons for creating these social networks and exchanging information is to understand health, either from an individual or communal perspective [9]. Within these networks, young people are the most digitally connected members, both as active and passive users [10]. Nevertheless, adolescents and early adults are in a critical life stage, in which both self-identity and healthy or unhealthy behaviors are shaped [8,11]. Mental health issues such as depression, and physical disorders such as sexual infections, are more common in this group [11–15].

Recent research on this topic has focused on the relationship between social networks and health issues, both as prevention or educational tools, and as risk factors [6,16]. In this sense, researchers have explored the health-damaging effects of social media [5,15,17], or its side effects, such as isolation, depression, and eating disorders [18,19]. Different factors, such as gender or cultural background, have been linked to these side effects [10,12,20].

Other studies have explored the beneficial use of these networks for delivering health interventions [14,17], especially health education [21,22]. Engaging patients in health communities is also a topic of research, often focused on specific health problems or social support [22].

Overall, social media appears to have been used in different ways, depending on the user's health and behavior [23,24]. Based on this, a previous study was carried out in Scopus using the terms "social media", "health", and "young people". From this initial research (1785 documents), more recent publications and those published in journals with a high impact factor were used to represent the increase in the reach of social media and health (Table 1). Table 1 summarizes some of the latest publications regarding social networks as health problems or interventions. This research focused on the latest publications in major journals in the health field, such as the *Journal of Medical Internet Research* [25]. In this sense, the results showed that the health and education area tend to focus on the positive outcomes of using social networks. Meanwhile, the psychology area tends to study the side effects of using social media (Figure 1).


**Table 1.** Main areas of research on social networks related to health during the last 10 years.


**Table 1.** *Cont*.

With this background, the principal objective of the present paper was to determine the tendencies of publications focused on social networks applied to health during the last 40 years (from 1978 to 2018). Additionally, the second objective of this study was to determine the link between social networks, health, and young people. The purpose of these objectives was to better understand the interaction of social networks in health, in order to assist the decision-making of health professionals and contribute to effective health education.
