In this study, both groups consisted of 32 males (91.4%) and 3 females (8.6%). The mean age of patients in the intervention group was 37.97 ± 10.58 years, while it was 39.66 ± 9.94 years in the control group (P = 0.495). Table 1 illustrates that there were no significant differences in educational level, marital status, and occupation between the two groups (p>0.05). The mean methadone doses in the two groups were 20.30 ± 8.81 cc and 18.40 ± 7.72 cc, respectively, with no significant difference (P = 0.337). Additionally, the mean duration of methadone use in the intervention and control groups was 6.01 ± 4.20 years and 4.91 ± 3.62 years, respectively (P = 0.245). There were no significant differences between the groups in terms of a history of using other drugs, smoking, neurological and mental diseases, suicide attempts, or use of psychiatric medications (p>0.05).

The HAM-D, used to assess the severity of depression, consists of 17 items, with each item scored on a scale from 0 to 4. This scale was developed by Max Hamilton in 1960 and is widely used in clinical settings. The scale has demonstrated high reliability and validity across various populations [22].

Before the intervention, the mean HAM-D score in both groups was 19.64 ± 3.52 and 19.45 ± 3.11 respectively, indicating no significant difference between the two groups (P-value=0.709). However, after the intervention, the sham tPBMT group consistently displayed significantly higher HAM-D scores immediately, one month, and three months later (P-value=0.001). At the end of the first and third months, patients in the LLL group had lower depression scores than the control group compared to pre-treatment, with significant effect sizes of 3.79 and 3.75, respectively.

Assessment of depression severity one-month post-intervention revealed that in the sham tPBMT group, 33 individuals (34%) had no depression, while none in the tPBMT group were without depression. Mild depression was observed in 55 individuals (56.7%) in the sham tPBMT group and 17 individuals (23%) in the tPBMT group. Furthermore, moderate depression was present in 9 individuals (9.3%) in the control group and 33 individuals (44.6%) in the tPBMT group. Lastly, severe depression was found in 24 cases (32.4%) in the sham tPBMT group and none in the tPBMT group (P = 0.001). (Table 2, Figure 2)

The score of depression, anxiety, and opioid craving of patients in the LLLT and control group before and after intervention

For assessing anxiety, the Hamilton Anxiety Rating Scale (HAM-A) was used, which contains 14 items, with scores ranging from 0 to 56, where higher scores indicate greater anxiety. The HAM-A, developed by Max Hamilton in 1959, is a widely recognized tool for assessing anxiety severity in clinical settings. This scale also shows strong validity and reliability [23].

Before the intervention, the average HAM-A scores in both groups were 21.00±5.93 and 20.27±6.67, respectively, with no significant difference between the two groups (P-value = 0.451). However, after the intervention, the sham tPBMT group consistently showed significantly higher HAM-A scores immediately, one month, and three months later (P-value=0.001). At the end of the first and third months, patients in the LLL group had lower depression scores than the control group compared to pre-treatment, with significant effect sizes of 1.48 and 1.51, respectively.

Specifically, one month after the intervention, anxiety was absent in 3 individuals (3.1%) in the sham tPBMT group, while none were without anxiety in the tPMBT group. Mild anxiety was observed in 92 individuals (94.8%) in the sham tPBMT group and 33 individuals (44.6%) in the tPBMT group. Mild to moderate anxiety was reported in 2 individuals (2.1%) in the sham tPBMT group and 29 individuals (39.2%) in the tPBMT group. Finally, moderate to severe anxiety was found in 12 individuals (16.2%) in the sham tPBMT group and none in the Tpbmt group (P-value = 0.001). (Table 2, Figure 2)

For evaluating opioid cravings, the Opioid Craving Scale (OCS) was utilized. The OCS consists of 15 items, with scores ranging from 0 to 60, with higher scores indicating more intense cravings. This scale is specifically designed for assessing cravings in individuals with opioid use disorder and has been widely validated in clinical studies [24].

Before the intervention, the mean OCS scores in both groups were 22.42 ± 3.50 and 22.76 ± 3.31, respectively, showing no significant difference (P-value =0.528). However, post-intervention, the sham tPBMT group consistently exhibited significantly higher OCS scores immediately, one month, and three months later (P-value=0.001). At the end of the intervention, first and third months, patients in the LLL group had lower depression scores than the control group compared to pre-treatment, with significant effect sizes of 2.40, 4.13, and 4.15, respectively. (Table 2, Figure 2).