Identification of common words to improve self-confidence in Japanese students with subthreshold depression

Background Subthreshold depression (StD) is more common than major depressive disorder. Objective The study aimed to identify common words to improve self-confidence in Japanese university students with StD for developing a smartphone application to help those with StD. Methods In this cross-sectional study, words participants used to improve their self-confidence were gathered using self-report questionnaires in 154 university students in Japan. The words used to improve self-confidence were categorized using a computerized text analysis method based on the frequency of appearance. Results Participants were 154 male and females [StD group (n = 82) and healthy control (HC) group (n = 72); median age = 20 years]. A total of 290 words for improving self-confidence were identified. In the StD group, the keywords that appeared with the highest frequencies were "can", "let's try", "good luck", "able", and "don't worry". The keywords that occurred with the highest frequencies (the top eight) were common across both groups. The keywords were grouped into eight categories. The "encouragement" and "praise" categories were found in the responses of more than 80% of participants in both groups. Frequencies of the "determination" and "trust" categories were significantly higher in the StD group than in the HC group. Conclusions We conclude that "can", "let's try", and "good luck" are the most common words that Japanese students with StD use when describing how they improve their self-confidence. Future work will use these common words to develop a smartphone application to help those suffering from StD.