The present study identified three distinct trajectories of loneliness in Chinese adolescents during the last phase of the COVID-19 pandemic. Around 4.8% of the participants reported “increasing high loneliness”, 36.5% “increasing medium loneliness”, and 58.7% “decreasing low loneliness”. In the 20 months until the end of the pandemic, loneliness levels increased remarkably in the highest and medium loneliness trajectories, and decreased slightly in the lowest trajectory. Factors at T0 including lack of physical activity, lower social support, poorer mental health literacy, and having study problems, were all risk factors for being in a higher loneliness group. There was also evidence that being female, higher grade, and lower household income predicted being in the medium loneliness class, although not the highest class. The adolescents with “increasing high loneliness” and “increasing medium loneliness” were more likely to report emotional problems, peer problems, hyperactivity and conduct problems. They also had higher increases of these problems from T0 to T3 compared to those with “decreasing low loneliness”.
It is concerning that 41.3% of participants were in the medium and high loneliness trajectories across the four time points. At T3, 32.2% of adolescents had loneliness total scores above the cut-off score and were considered as “lonely” [30]. Data based on nationally representative samples within World Health Organization regions pre-COVID-19 suggest that only 9.2–14.4% of adolescents experienced loneliness [6]. Our study did not include adolescents outside of Taizhou, but the findings nonetheless indicate that there are a large number of adolescents feeling high levels of loneliness in China. It is also notable that loneliness for the medium and high groups had a consistent growth, particularly around the end of the pandemic. The start of the survey at T3 coincided with one month following the official end of zero-COVID-19 policy in China. Although there are no more social distancing measures, people went through an abrupt outbreak of COVID-19 before life returned to normal, so it might be a response to worries over infection for themselves and those they care about. However, it is also possible that fatigue due to the long-term pandemic and socially restrictive measures may have exacerbated the existing feelings of loneliness. In regards to the lowest loneliness trajectory among 58.7% of participants, there is a gradual decrease over the 20 months, with the lowest level recorded at the last assessment. Whether the indication of improvement of loneliness in this group is a result of the end of the pandemic and social distancing measures remains to be explored in future research. Nevertheless, it is striking that loneliness levels had marked changes over time. Our findings suggest that the adolescents with low level of loneliness showed adaptation to the circumstances, whereas those with medium to high levels had growing sensations of loneliness.
The finding on physical inactivity being a risk factor for loneliness echoes previous studies during both the pandemic [31] and ordinary times [32]. Several intervention studies found that physical activity programs contributed to a reduction in loneliness [33, 34]. Potential moderators and mediators may exist within this relationship such as social support, given that social elements were involved in many physical activity interventions [32]. Similarly, our finding that adolescents with low and medium social support had higher odds of being lonelier than those with high support is consistent with research showing a negative association between social support and loneliness [35]. There has been some evidence that friend support had a greater impact on feelings of loneliness than family and significant other support as adolescents begin to expand the connections beyond their family circle and attach increasing importance to friendship [35]. It is notable that poor mental health literacy was a risk factor for higher loneliness. People without sufficient mental health literacy are at risk for both lack of knowledge around positive health behaviors and difficulties identifying psychosocial problems and making sound decisions [36]. Those with greater mental health literacy may be more likely to obtain adequate assistance and utilize available resources to address their psychosocial problems [37]. Having study problems was also identified as a risk factor for loneliness. Existing studies have confirmed the influence of loneliness on student engagement and academic achievement [38], while our study proved that adolescents with self-perception of poor academic performance were also more likely to have chronic loneliness. These variables, on the other hand, can be considered as resilience factors that protect against loneliness, namely regular physical activity, high level of social support, good mental health literacy, and improvement in academic performance, highlighting the importance of future interventions targeting these aspects which could potentially reduce perceptions of loneliness in adolescents.
Furthermore, adolescents with medium and high levels of loneliness demonstrated a greater likelihood of both internalizing problems (emotional and peer problems) and externalizing problems (hyperactivity and conduct problems) compared to those in the group with low level of loneliness. In most cases, individuals with medium and high levels of loneliness also reported a significant increase in mental health problems from T0 to T3, which could be attributed to the increasing prevalence of chronic loneliness. Chronic loneliness is closely associated with depressive symptoms, maladaptive social cognition, and poor recovery following a mental health crisis [39–41]. Researchers have suggested that transient loneliness may serve an evolutionary purpose by prompting people to reestablish connections for the sake of survival and genetic continuity [42]. However, chronic loneliness poses potential risks due to its tendency to create a self-reinforcing loneliness loop where lonely persons become increasingly distrustful of others and anticipate negative relationships, and as a result, they would prefer to avoid future social interactions [42]. Our results are also consistent with existing studies about loneliness trajectories which found that both high and medium trajectories were at increased risk for depression, anxiety, self-harm and suicidal ideation [19, 43]. All these findings indicate that adolescents who experience chronic loneliness at any degree, not limited to those with high level of loneliness, may benefit from strategies aimed at decreasing loneliness.
One noteworthy strength of our study is the use of longitudinal data permitting examination of changes in loneliness from four timepoints during the last phase of the pandemic. Another strength pertains to the investigation of the impact of loneliness trajectories on externalizing problems including hyperactivity and conduct problems, as most of the existing studies just focus on internalizing problems such as depression and anxiety. However, some limitations of our study should be taken into account. First, although we used cluster sampling from 30 schools in Taizhou, adolescents from other areas in China were not included, which may lead to inaccurate estimates regarding loneliness trajectories in Chinese adolescents. Second, even though reliable assessment tools were utilized in our study, the measures employed for loneliness and mental health problems are brief version or screening scale, which might limit their capacity to offer comprehensive insights. Third, these analyses focused on loneliness trajectories in adolescents during the pandemic, but how they compare to experiences of loneliness in the post-pandemic period remains to be investigated in future studies.
There are a number of implications from our findings. The results presented here indicate the exceptionally high level of loneliness with no signs of improvement for many adolescents, which had great impact on internalizing and externalizing problems. The study highlights the importance of considering how to tackle loneliness both within the context of COVID-19 and more generally. It is consistent with the goal of a new Commission launched recently by WHO to address loneliness as a pressing health threat and foster social connection [44]. In order to deal with the growing number of reports about loneliness in adolescents, due in part to the COVID-19 pandemic, it is necessary to design effective and easy to implement strategies involving the wider school community. Many parents and caregivers may struggle to spot signs of loneliness and mental health problems in adolescents, although they have a lot of impact on how their children think. Thus, efforts should be made to provide them with regular low-level training on how to identify indications of these problems combined with guidance for dealing with them and information about helpful resources. Regular training sessions for teachers and support staff in school would also bring benefit to students as teachers play important role in improving adolescent mental well-being. Apart from common mental health problems, adolescent loneliness should be monitored continuously in school, and timely support should be offered to those who report loneliness, particularly chronic loneliness [43]. Our results of the predictors of loneliness trajectories suggest that strategies to improve physical activity, social support, mental health literacy, and assist students with poor academic performance may help reduce their loneliness. Some interventions aimed at tackling loneliness, such as social prescribing [45], should be adapted for adolescents and be promoted to make sure that young people are aware of them. Together, these approaches may help lessen adolescent loneliness and possibly decrease their risk of internalizing and externalizing problems.