I. Research Background and Purpose A recent trend of worsening mental health among young people around the world has been observed. This trend seems to have started between 2010 and 2014, coinciding with the spread of smartphones. This study aimed to investigate the effect of the age of first smartphone ownership on the mental health of young people aged 18-24, and to determine the cumulative effect of smartphone use. II. Research Methods • Subjects: 27,969 adults aged 18-24 (17,406 women, 10,050 men) • Period: January - April 2023 • Coverage: 41 countries (North America, Europe, Latin America, Oceania, South Asia, Africa) • Assessment tool: Mental Health Quotient (MHQ) ◦ A comprehensive mental health assessment tool consisting of 47 items ◦ Assess mental function in 6 dimensions (Mood & Outlook, Social Self, Adaptability & Resilience, Drive & Motivation, Cognition, Mind-Body Connection) • Additional questions: Age of first smartphone ownership, experience of childhood trauma III. Main findings A. Overall Mental Health: ◦ The older the age of first smartphone ownership, the higher the MHQ score ◦ Greater impact on women: - 74% mental health issues at age 6 vs 46% at age 18 - Negative average MHQ score at age 6 (indicates serious mental health problems) ◦ Slightly less impact on men: - 42% when owned by 6 year olds vs 36% when owned by 18 year olds - MHQ scores 20-25 points higher than women in all age groups B. Areas that showed the greatest improvement: ① Social Self: ◦ Includes self-image, self-confidence, ability to form and maintain interpersonal relationships, and ability to cooperate. ◦ For women, the score increased by about 50 points from age 6 to 18 (16% improvement) ◦ For men, an increase of about 25 points ② Mood & Outlook: ◦ Significant improvements observed in both women and men ③ Adaptability & Resilience: ◦ Significant improvement in women, no significant change in men C. Issues with the greatest decrease: ① Suicidal thoughts: ◦ Female: 5.8 points when owned at age 6 → 3.6 points when owned at age 18 ◦ Male: 4.1 points when owned at age 6 → 3.2 points when owned at age 18 ② Aggression toward others ③ Feeling separated from reality ④ Hallucinations (for women) ⑤ Addiction (for women) IV. Analysis and Interpretation A. The importance of social interaction: ◦ Reduced face-to-face interaction due to smartphone use (estimated at 1,000-2,000 hours per year) ◦ Virtual interactions do not adequately replace the development of real social skills ◦ Reduced opportunities for learning through multiple sensory modalities, such as facial expressions, body language, vocal tone, touch, and smell. B. Gender differences: ◦ Women are more sensitive to the age of smartphone use ◦ Possible causes: Differences in online activity patterns (women prefer social media, men prefer games), differences in interpersonal functioning, biological factors, etc. ◦ Further research is needed to determine the exact cause. C. Long-term effects: ◦ Early smartphone use may have lasting effects on mental health in adulthood ◦ Possible negative impact on the development of social skills and emotional stability ◦ Association with serious mental health problems, such as suicidal thoughts, aggression, and detachment from reality D. Relationship with childhood trauma: ◦ The relationship between smartphone ownership age and mental health remains even in the absence of trauma ◦ This suggests that the influence of smartphones may be independent of other factors. V. Limitations of the Study • Shows correlation but difficult to prove causation • Difficulties in conducting long-term experimental studies due to ethical issues • Further analysis is needed on country-specific and cultural differences. • Does not distinguish between the influence of smartphones and tablets • Limitations of self-report questionnaires (distortion of memory, subjectivity, etc.) VI. Conclusion and Suggestions The results of this study strongly suggest that delaying smartphone use in children and adolescents may have positive effects on mental health, particularly in the development of social skills and emotional stability. Therefore, I make the following suggestions: ① Parents and educators should carefully consider the timing of children’s smartphone use. ② Activities that can supplement face-to-face social interaction when using smartphones should be encouraged. ③ Policymakers should reexamine guidelines regarding children and adolescents’ use of digital devices. ④ Additional long-term studies are needed to better understand the long-term effects of smartphone use. ⑤ A customized approach that takes into account gender differences may be necessary. ⑥ We must strengthen digital literacy education to enable children and adolescents to use technology in a healthy way. Based on these findings, we emphasize the need for a balanced approach to the use of digital devices for the healthy development of children and adolescents. While recognizing the benefits of smartphones, we must be careful not to let them replace important experiences and interactions in the real world.