Introduction:
Mindfulness-Based Art Therapy (MBAT) is an integrative intervention that combines mindfulness training with creative expression. While MBAT has shown efficacy in reducing depressive symptoms, little is known about the temporal sequence of psychological changes during therapy. Understanding the order in which changes occur may improve intervention planning and personalization.


Purpose:
This study aimed to explore session-to-session changes in mindfulness, rumination, and affect among hospitalized patients with depressive disorders participating in MBAT. We investigated whether mindfulness precedes changes in cognitive and emotional processes during therapy.


Method:
Forty-seven inpatients diagnosed with major depressive disorder or bipolar depression took part in twice-weekly MBAT sessions over several weeks. Each session included mindfulness meditation, mindful art-making, and group reflection. Participants completed self-report diary assessments of mindfulness, rumination, and affect twice weekly. Multilevel and autoregressive modeling was used to analyze within-person temporal dynamics.


Results:
Participants demonstrated increased mindfulness and positive affect, and decreased rumination and negative affect over time. However, session-to-session changes in mindfulness did not predict subsequent changes in rumination or affect. Instead, more frequent home mindfulness practice was associated with reduced rumination, while engagement in art activities was linked to improved affect. Temporal effects appeared to oscillate, with greater variability among participants with shorter therapy durations.


Conclusions:
These findings highlight distinct roles for mindfulness and art components in MBAT: mindfulness may target cognitive patterns such as rumination, while art activities enhance emotional regulation. The absence of lagged effects suggests that changes may not follow a simple linear progression. Future studies should examine how session structure and timing influence outcomes and incorporate control groups to better isolate treatment-specific effects.