Persistent depression has been suggested to be associated with autistic traits in people of working age. This study aimed to clarify which autistic characteristics at the initial visit were associated with persistent depression at the 12 week follow-up in a primary care setting. Newly depressed outpatients aged 24-59 years with no history of autism were asked to complete the 50-item autism spectrum quotient (AQ) and the Beck depression inventory (BDI) at baseline and 12 week follow-up (N = 123, males: 48%, age: 37.7 ± 9.15 years). Nearly 40% of participants had an AQ score ≥ 26. Significant differences were observed between the group with remitted depression (N = 43) and those with persistent depression (N = 80) in educational years and AQ "attention switching" and "attention to detail" subscale scores. In addition, a statistically significant decrease in the total AQ and the "communication" and "imagination" scores were observed in the remitted group, while no such change was observed in the group with persistent depression. It remains unclear whether the self-perceived severity of communication and imagination traits in persistent depression was due to the state of persistent depression or a kind of premorbid autistic trait. The results suggest that high levels of autistic traits are frequently present in adults with depression. High "attention switching" and "attention to detail" scores in AQ screening at the first visit might predict the persistence of depressive symptoms after 12 weeks in adults with depression, while total AQ scores, especially for "communication" and "imagination" items, might be state-dependent.