Depression in autism: Unmasking the mediating role of mentalization, attachment, perceived social support, and psychological flexibility

BackgroundDepression is highly prevalent in autistic individuals, yet its underlying psychological mechanisms remain insufficiently understood, especially in populations who self-identify as autistic but lack a formal diagnosis. MethodsUsing a moderated mediation approach (structural equation modeling), we investigated how autistic traits relate to depressive symptoms in three groups: individuals with clinically diagnosed autism (ASD, N = 136), self-identified autistic individuals without formal diagnosis (ASD-sd, N = 100), and neurotypical controls (N = 1566). Five psychosocial mediators were tested: mentalizing, anxious and avoidant attachment, perceived social support, and psychological flexibility. ResultsDepressive symptoms were significantly higher in both autistic groups compared to neurotypical controls. The association between autistic traits and depressive symptoms was fully mediated by a combination of psychological flexibility, attachment style, mentalizing, and perceived social support. Among these, psychological flexibility emerged as the strongest and most consistent mediator across all groups. In contrast, mentalizing showed an indirect effect only in the non-ASD group, while avoidant attachment was a significant mediator solely in the clinically diagnosed ASD group. Perceived social support showed a modest indirect effect only in the non-ASD group. ConclusionsOur findings support a transdiagnostic model in which psychological flexibility plays a central protective role against depression across varying levels of autistic traits. Meanwhile, attachment-related and social-cognitive vulnerabilities contribute in different ways depending on diagnostic status. These results underscore the clinical importance of individualized interventions targeting such modifiable factors. Mentalization-based treatment, adapted for neurodiverse populations, may offer a promising framework for addressing both common and subgroup-specific mechanisms. Lay abstractMany autistic people experience depression, but we still know little about why this happens and what psychological factors are involved, especially for those who see themselves as autistic but dont have a formal diagnosis. We studied three groups: people with diagnosed autism, people who self-identify as autistic, and people without autism. We wanted to understand which psychological traits might explain why autistic traits are linked to depression. We found that a skill called psychological flexibility (being able to stay present and adapt to difficult emotions) was the most important protective factor in all groups. Other factors, like how people think about relationships (attachment) and how well they understand themselves and others (mentalizing), were only important for some groups. These findings suggest that therapies which improve flexibility and help with emotional connection may reduce depression in autistic people and those with high autistic traits.