The findings of the present study showed that the ACT intervention method can be considerably effective in increasing perceived social support and hope level and reducing caregiving burden in mothers with DS children. In explaining the results, it can be said that ACT is a mindfulness-based and behavior change treatment approach that emphasizes accepting internal experiences, clarifying values, and committing to actions based on them. This treatment helps individuals to accept negative emotions rather than avoid them and move towards their meaningful goals. Previous research has shown that ACT can play an effective role in improving mental health, reducing anxiety and stress, and increasing psychological flexibility (
25). In particular, this treatment has been effective in improving the quality of life (QoF) of people with chronic stress, including parents of children with special needs (
26). The ACT has six basic processes, including acceptance, cognitive decoupling, mindfulness, self-context, value clarification, and committed action. These processes help individuals focus on performing adaptive behaviors that are consistent with their values instead of engaging in negative thoughts (
27). One of the important features of ACT is its ability to reduce experiential avoidance, which helps people accept unpleasant emotions and actively face life challenges instead of running away from them (
8-
10).
Similar to this research, various other research have been done previously, the findings of which are consistent with the results of the present study. Hayes et al. showed that ACT can effectively increase social support and hope in individuals (
25), and the results of the present study also confirmed the high effectiveness of ACT in improving the aforementioned indicators. In addition, a study by Arch and Craske showed that ACT plays an important role in improving emotional regulation and reducing stress, which is consistent with the findings of the present study (
28). In another study conducted by Aghababaee and Alipour, the effectiveness of ACT focusing on compassion on emotional processing and self-care in adolescent girls with premenstrual syndrome was examined, and the results indicated an improvement in emotional processing and self-care, which could be related to increased hope (
29). Also, in a study by Shavaran and Dehghani Champiri investigated the effectiveness of ACT on perceived social support and life expectancy in caregivers of patients with amyotrophic lateral sclerosis (ALS), and the results showed that this treatment increased perceived social support (
30). Saeedifard et al. indicated that ACT-based group therapy increased the resilience of mothers of children with intellectual disabilities, which can lead to a decrease in caregiver distress (
31). Carvalho et al. compared the influence of ACT and compassion-focused therapy (CFT) for people with chronic illnesses; the results indicated that both interventions were effective in reducing psychological stress, improving QoF, and increasing emotional regulation. However, ACT had a greater effect on acceptance of the illness, while CFT considerably improved self-compassion and reduced feelings of shame (
32). Nikonezhad et al. compared the effectiveness of ACT and CFT in controlling emotions in women with multiple sclerosis (MS) (
33). The results show that both methods are effective in reducing anger, depression, and anxiety and increasing positive affect, but CFT has provided better results in reducing anxiety and increasing self-compassion, while ACT has helped improve acceptance of the situation and commitment to personal goals. The researchers of the aforementioned studies suggested that the choice of treatment should be based on the individual needs of each patient (
33). In another study by Mousavi et al. compared the effectiveness of ACT, FCT, and ACT enriched with CFT (ACT+CFT) on social adjustment in women with depression and marital conflict. They showed that all three methods are effective, but “ACT+CFT” had a greater effect on improving social adjustment and reducing marital conflict. The researchers of the aforementioned study emphasized that the combination of compassion and acceptance elements can help increase the effectiveness of the treatment (
34).
In line with the finding of this investigation, in a study done by Ne’matpour et al., they observed a considerable effect of ACT on the perceived social support of mothers with children with autism (
35). In addition, Kashfi et al. also showed a positive and considerable effect of ACT on life expectancy and decision-making ability of addicts (
36). In another study by Fadae et al., they evaluated ACT as effective on the happiness and psychological adjustment of parents of mentally retarded children, and its findings showed that the hopefulness of students with substance-dependent parents was considerably increased under the influence of acceptance and commitment-based education (
37). In the study by Rostami et al., ACT and coping strategies were considerably effective in reducing anxiety and hopelessness in mothers of autistic children (
38). Also, Poddar et al. examined the considerable effects of this treatment method among parents of children and adolescents with autism, and the results indicated positive effects of this treatment on anxiety, depression, psychological flexibility, and QoF (
39). Maughan et al. (2024) also found positive effects of this treatment on improving depression in mothers of autistic children (
40). Positive effects were also observed in the study by Marino et al. following the use of this treatment in considerably improvements in psychological flexibility, state of awareness, personal values in daily life, and stress of mothers of autistic children, and parents' understanding of the destructive behaviors of the autistic child (
41). The results of this research and the results of other similar studies indicate a positive and considerable effect of ACT on increasing social support, increasing hope, and reducing the suffering of caring for mothers of children with illnesses or special needs.