Dear Editor
The prevalence of suicide among people with substance use disorders (SUDs) remains a significant public health issue worldwide. A review of the medical literature suggests that both substance addiction and behavioral addictions are closely associated with increased suicidal thoughts and attempts. A systematic review by Armon et al. found that 35% of individuals with SUDs reported suicidal ideation, while 20% had attempted suicide in the past year [1]. Among behavioral addictions, individuals with gambling disorder (22.9%) and sexual addiction (18.2%) reported the highest rates of suicidal ideation [2]. Factors, such as a history of previous suicide attempts, depression, and polysubstance abuse significantly increase the risk of suicide. Low socioeconomic status and lack of family support also contribute to increased vulnerability [2].
Methamphetamine use is significantly associated with suicidal ideation and behavior. Approximately 50% of patients with acute methamphetamine intoxication have reported suicidal ideation, with higher rates observed in women [3]. Methamphetamine users experienced a 16-fold increase in hospitalizations for suicidal ideation from 2008 to 2019, particularly among those aged 26 to 40 years [4]. Methamphetamine dependence is linked to increased impulsivity and aggression, which are important risk factors for suicide. Patients who used methamphetamine alone or in combination with other substances exhibited a higher risk of suicide compared to those who used other drugs. Chronic methamphetamine use, especially over more than a year, significantly increases the likelihood of suicidal thoughts, and visual hallucinations are also considered a significant risk factor [5]. 
Opioid users also exhibit high rates of suicidal thoughts and attempts. A systematic review by Khanjani et al. found that the prevalence of suicide attempts among the heroin-abusing population is approximately 30%, and the rate of death by suicide is approximately 3% [6]. In a cohort study, individuals who used opioids for chronic pain were 4.44 to 7.23 times more likely to attempt suicide than non-users, especially at higher doses [7]. Higher prescribed doses of opioids are associated with an increased risk of suicide. For example, doses greater than 100 mg per day have been linked to more than a twofold increased risk of suicide [8]. The factors contributing to suicide among opioid users are complex and multifactorial, often including emotional distress, physical dependence, and an increased prevalence of comorbid psychiatric disorders.
Methadone is widely used in agonist therapy to reduce withdrawal symptoms and cravings in opioid-dependent individuals. Although methadone has been shown to reduce overall mortality among opioid-dependent patients, its effect on suicide risk is quite slight. A systematic review by Santo et al. indicated that opioid agonist treatment, including methadone, is associated with a relative reduction in the risk of suicide (relative risk of 0.48) compared to untreated individuals. However, the risk of suicide is influenced by the dose of methadone and the mental health of the patient. Higher doses of methadone may increase the risk of suicide in patients with psychiatric illnesses [9]. Conversely, appropriate doses of methadone may significantly reduce the risk of suicide in patients without psychiatric problems [7].
Given the different effects of various drugs on suicide, this analysis emphasizes the importance of appropriate treatment approaches for patients with SUDs. Methamphetamine and opioids each contribute uniquely to suicidal ideation, with methamphetamine increasing impulsive and aggressive tendencies, while opioids affect emotional states and dependence. Methadone, although useful in reducing withdrawal symptoms and mortality in opioid users, requires careful dosage management to minimize adverse mental health consequences. Further research should examine the underlying pathways linking each type of substance to suicide risk and explore alternative treatment strategies, such as buprenorphine or naltrexone, which may offer similar benefits with potentially lower suicide risks.
In conclusion, the findings emphasize the need to enhance the quality and individualization of treatment for patients with SUDs, especially those undergoing methadone maintenance treatment (MMT) and non-pharmacological interventions, such as various psychotherapy methods. While methadone has proven effective in reducing mortality and suicide risk among opioid users, its safety and effectiveness are influenced by factors such as dosage, mental health status, and compliance with treatment. Future research should focus on optimizing methadone dose adjustment strategies and comparing the effectiveness of agonist replacement treatment options in reducing suicide risk within this vulnerable population.



References

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