Around the world, depression is one of the most common mental health problems and is ranked by the WHO as the single largest contributor to global functional disability (1). In fact, mental disorders account for 30% of the non-fatal disease burden worldwide and 10% of the overall disease burden, including death and disability (2). The total number of people living with depression worldwide in 2015 was estimated to be 322 million, or 4.4% of the total population. Nearly half of these people live in the South-East Asia Region, and Western Pacific Region (1), which include India and China, for example.

The prevalence of depression affects different age groups, and in various analyses of depression in youth, it was found that the prevalence of depression in young students was about 27.2% (3), about 5% of people aged 65 and over suffered from depression (4). In the first-episode group, there is a predominance of young adult (5). Youth morbidity can have a serious impact across the life cycle (6); the earlier the age of onset, the higher the risk of obsessive-compulsive, interpersonal sensitivity, depression, hostility, paranoid ideation, and psychoticism, the more pronounced the clinical features and the higher the degree of impaired social function (7). Early and effective intervention is therefore needed.

Research shows that people with depression experience impaired social functioning (6–9), even up to 20% of depressed people have severe social anxiety (9). The study finds depression with social anxiety associated with worsening depression (8, 10–12), cases with impaired social function have more physical symptoms, more residual symptoms of depression, and less satisfaction with the quality of life (13). After depressed disease are prone to heavy psychological burden and anxiety, fear and other negative emotions, but individual in society, the essential need to mix with all sorts of people, because of interpersonal communication is impaired, patients unable to integrate into the collective and society, unable to perform normal in daily work, and then form a vicious circle (14). While interpersonal harmony and emotional stability play complementary roles, social training can reduce social anxiety and reduce depressive symptoms. A study of prenatal depression patients who received 12-week social support training showed that attending a social support group reduced depression and social anxiety and improved intimacy (15). Through the vulnerability model of social skills deficit (16), Moeller RW verified that the low level of social skills of college students is correlated with the high rate of loneliness. The development of social skills programs can reduce the loneliness of college students with depression and anxiety, and further reduce their mental health burden (17). Early social skills training can be effective in reducing social anxiety and depression (18–20).

Clinical social skills training include interpersonal therapy (IPT) (21), social skills training (SST) (22), dynamic interpersonal therapy (DIT) (23), and so on. IPT is currently the mainstay of treatment for social dysfunction in patients with depression. It was originally developed by Gerald Klerman and Myrna Weissman as a psychological treatment for outpatients with severe depression (24), based on “psychobiological approach” of Adolf Meyers (25), “Interpersonal School” of Harry Stack Sullivans (26) and “Attachment theory” of John Bowlbys (27). Numerous clinical randomized controlled trials have confirmed the effectiveness of IPT in the treatment of patients with depression (28). But for now, IPT is more focused on patients with postpartum depression (21) and helping new mothers adjust to the role change. SST refers to helping patients simulate normal communication and communication methods by teaching patients’ social communication skills, so as to stimulate patients to find the joy of life and play a therapeutic purpose (22). The training includes four main areas: language skills, basic interpersonal skills, self-confidence, and skills in helping others and seeking help. DIT is based on building alliances of help and trust, and emphasizes the connection between this alliance and the patient’s past experiences (29). Take the lead of the therapist to help the patient relax and communicate effectively while dealing with interpersonal challenges (30). These social skills training exercises have been shown to be effective in guiding social function in people with depression, but they are mainly aimed at people of all ages with depression. The vast majority of evidence focuses only on depression itself, ignoring the differences in the context of the family environment at different ages, taking into account the age-specific nature of the youth population, which differs from adults and older people in the way they approach relationships (31). All of these training lack relevance to the youth depression population, and there is an urgent clinical need for a social intervention for a young adult with depression.

Program for Education and Enrichment of Relational Skills (PEERS) is a training program developed by Dr. Laugeson at UCLA (University of California, Los Angeles, Los Angeles, CA, United States) to address social skills deficits (32–34). It is a parent-assisted, manualized social skills training program for adolescents with ASD. PEERS training focus on key areas of social function for young people, including such as developing conversational skills, choosing appropriate friends, using humor, planning get-togethers, using good sportsmanship, and handling peer rejection, such as teasing physical bullying, gossiping, and disagreements. Teaching ecologically effective skills to nurture and maintain friendships using psycho-educational and cognitive-behavioral therapy techniques (35). PEERS training has been successively introduced and updated locally in Korea (36), Japan (37), Israel (38), the Netherlands (39), and Hong Kong (40), with good results in local ASD patients (41). Patients with ASD are often accompanied by depression, anxiety, intellectual disability, attention deficit, and other psychiatric comorbidities. The results of the study showed that after the PEERS intervention, patients’ social etiquette and social functioning scores improved significantly, their social communication skills, responsive and accepting behavior improved positively, and depressive symptoms were effectively reduced (40).

Since the development of PEERS training, a number of researchers have used various trials to evaluate the effect of PEERS training on the mental health of patients (42). It has been suggested that the PEERS program could help more people with impaired social functioning to exercise their social functions (40), such as people with depression. In North America, the PEERS training has been shown to be effective in reducing patients’ self-reported depressive symptoms (32) and has also been extended to patients with depression, anxiety, alcohol dependence, and other disorders (43, 44). This shows that PEERS training has a bright future as an intervention to improve social functioning, similar to IPT, SST, and DIT.

Considering the different cultural backgrounds, social civilizations, and interpersonal styles in mainland China, the applicability of the PEERS training to young Chinese patients with depression still needs to be further optimized and validated. Combining PEERS with the Chinese context and exploring the construction of a more suitable social training program for Chinese young people with depression has positive clinical implications for the new development of psychiatric treatment in China. Influenced by local, regional differences, this trial also provides a reference for the introduction of a locally adapted PEERS training program for depressed youth in countries around the world, contributing to the global spread of PEERS training programs.

The burden of illness caused by depressive disorders is high, both in terms of personal distress, impaired social functioning and relationships, reduced quality of life, and socio-economic costs (56). Evidence from numerous studies shows that people with depression suffer from a social impairment, which in severe cases affects their normal work life (9). It is vital to improve the current situation of impaired interpersonal barriers in people with depression and to develop their social skills and abilities. Several of the currently available interventions for social functioning have certain shortcomings of their own, in addition to being insufficiently targeted. For example, IPT is mostly individualized and requires one-to-one interaction between the therapist and the patient, which can consume more human, material and financial resources; SST contains fewer entries, and the training of the patient is not yet comprehensive and still needs to be enriched; DIT is quite demanding for the therapist, requiring him/her to calmly analyze the self, immerse himself/herself in psychoanalytic therapy and always bear in mind the exploratory and analytical nature of the method (57).

The PEERS program was initially developed as an empirically supported social skills intervention program for young people with autism (35), involving both parents and peers (58). In the subsequent development of PEERS, many scholars have verified that the PEERS program has a positive impact on the improvement of patients’ depressive mood (32, 59, 60). In terms of improving social functioning, the PEERS program has the unique advantage of adding the involvement of parents, peers and a greater need for peer socialization among the youth population, increasing the motivation of the youth depressed population to participate. As the most specific stage in the development of depression, young people need to deal with different social partners, and psychological interventions and practical training for depressed people during this period can yield better results (16, 17). PEERS is delivered as a course, which reduces human and material resources and allows for timely practice of what is learned in the course, with the trainer simply guiding and the classroom being more patient-centered, making it simple, effective, and easy to implement. The PEERS program meets the needs of depressed young people for peer socialization and fills the gaps in several existing social functioning intervention programs.

Compared with foreign cultures, Chinese people are more introverted in emotional expression, and Chinese young people with depression are more difficult to express their feelings. The PEERS program proposed for this trial combines the national conditions of the country and the physical and mental characteristics of young people with depression. Localized PEERS training program has been constructed by experts to make the content more scientific, purposeful and relevant based on access to a large database and expert working sessions. The optimized PEERS program compensates for the shortcomings of several existing social skills training programs mentioned above, observes the clinical manifestations and signs and symptoms of young depressed patients, combines their physical and psychological characteristics, simulates a real social environment, and trains depressed patients in small groups, enabling participants to enhance interactive communication.

The design of the experiment took into account the possibility of changes in the subject’s condition, and thus we set a 20% lost visit to ensure an adequate sample size. The intervention course is arranged in four interlocking sessions to refresh the knowledge taught and apply it to practice, while arranging for the coaches to take the lead and ensure the course is conducted properly, but more so to encourage the hands-on practice by the patients, using the class as an opportunity for patients to communicate and learn from each other, promoting their understanding of each other and helping each other to practice their social skills.

Before the formal trial began, a pre-experiment was conducted to examine both the motivation and cooperation of the study subjects. At the same time, the content of the sessions was improved to make the program more relevant to the actual needs of young people with depression, based on the subjects’ self-specific feelings and evaluations. The pre-experiment followed strictly to inclusion and exclusion criteria for the selection of subjects and was randomized to prevent cross-contamination between subjects. We found that all study participants cooperated positively with the study, were highly compliant and were able to successfully complete all training sessions without dangerous negative emotions or side effects, validating the reliability and safety of the training in this study. After the pre-experiment, social anxiety scores, social avoidance and distress mood decreased in the intervention group compared to the control group, while social self-efficacy scores increased relatively after the intervention, as detailed in Table 3.

If Chinese-specified PFEERS training is proven to improve depressed mood and enhance social skills in Chinese depressed youth populations, it could have significant implications for their recovery and prognosis. From a cross-diagnostic perspective, PEERS training may be a new time-saving and accessible method of training for health behavior change in other socially impaired populations, such as Chinese children with autism, youth with anxiety disorders, etc.

In conclusion, we hope that this study will provide evidence-based evidence for the application of PEERS training to the treatment of various types of socially impaired patients and provide a reference for the development of locally specific and targeted social skills training programs in each country.

The studies involving human participants were reviewed and approved by Huzhou Psychiatric Hospital’s Medical Ethics Committee. The patients/participants provided their written informed consent to participate in this study.

YH, QZ, and JS conceived and designed the project. YH, QZ, JS, and YL oversaw data acquisition and data interpretation. YH, JS, QZ, and LZ performed the statistical analysis. YL and MZ checked the statistical analysis. YH and JS wrote the manuscript. All authors reviewed, revised, and approved the final version of the manuscript.