Alteration of Whole Brain Amplitude of Low-Frequency Fluctuations and Fractional Amplitude of Low-Frequency Fluctuations in Patients With Depression After Acceptance and Commitment Therapy: A Resting-State Functional Magnetic Resonance Imaging Study

Objective This study aimed to explore the changes in brain functional activity before and after acceptance and commitment therapy (ACT) treatment in patients with major depressive disorder (MDD) and the correlation between brain functional changes and clinical symptoms. Methods We recruited 12 patients who met the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, criteria for MDD. Patients underwent clinical assessments and resting-state functional magnetic resonance imaging (rs-fMRI) scans before and after ACT intervention. The amplitude of low-frequency fluctuations (ALFF) and fractional ALFF (fALFF) maps were obtained after data preprocessing, and the ALFF/fALFF values of patients were extracted and compared. Pearson correlation analysis was used to analyze the correlation between fALFF/ALFF values and clinical symptoms. Results A total of nine MDD patients completed the study. The results showed that, following treatment, there was an improvement in psychological flexibility, along with a reduction in depressive symptoms. Additionally, MDD patients exhibited increased ALFF in the left inferior frontal gyrus and triangle, as well as increased fALFF in the left medial superior frontal gyrus following symptom remission. Pearson correlation analysis showed that fALFF of the left medial superior frontal gyrus at baseline was negatively correlated with the rate of Acceptance and Action Questionnaire, Second Edition (AAQ-II), change ( r = −0.76, P < 0.05). Conclusions We observed alterations in spontaneous activity in regions of the prefrontal cortex in MDD patients following ACT, providing preliminary relevant insights into understanding the neural mechanisms underlying the treatment of MDD by ACT.