Purpose <p>Autistic adults often face co-occurring depressive symptoms. While previous studies have focused primarily on depression in children with autism, this study aims to investigate the factors associated with depressive syptoms in autistic adults. By examining a broader range of variables including sociodemographic factors and autistic traits like sensory sensitivity and restricted and repetitive behaviors, we seek to gain a more comprehensive understanding of the elevated levels of depression within this population.</p> Methods <p>This quantitative study utilized a cross-sectional design. Two hierarchical regression analyses were conducted. The first analysis included all participants (N=438), focusing on demographic factors such as age, gender, income, in the first model and autistic traits such as repetitive behaviors, and depressive symptoms in the second model. The second analysis included a reduced sample (N=305) that additionally incorporated sensory sensitivity data.</p> Results <p>Older age, lower income, and a greater number of co-occurring psychosocial problems were significantly associated with higher levels of depressive symptoms.</p> Conclusions <p>Our research, unique by its large sample of adults with autism and innovative exploration of potential factors of influence, offers valuable insights into the unique challenges faced by autistic adults. Our findings highlight the difficulty older autistic individuals may encounter in accessing support services primarily designed for younger populations. Moreover, co-occurring problems and lower income can exacerbate these challenges, leading to instability and limited access to resources. These results underscore the urgent need for societal inclusion and tailored support systems to promote the mental well-being of autistic adults.</p>