Discussion

This scoping review aimed to provide an overview of current evidence on psychosocial interventions for individuals with severe MHCs and substance use in LMICs. We identified a limited number of primary studies focusing on intervention adaptation or testing in this population, with only four out of 13 studies being randomised controlled trials. These studies spanned eight LMICs, and their primary outcomes were varied, including substance use abstinence, treatment engagement and retention, reduction in psychiatric symptoms, functioning and suicidal behaviours.

The studies targeted a variety of substances, including tobacco, opioids, alcohol, khat and other drugs, using interventions such as early screening for dual conditions, tobacco cessation programmes, psychological interventions and psychosocial rehabilitation. However, there was no sufficient evidence on implementation processes, barriers or facilitators.

Some psychosocial interventions appear to be feasible and acceptable in LMICs among people with severe MHCs and SUDs. ^{Reference Asher, Hanlon, Birhane, Habtamu, Eaton and Weiss40} Tobacco cessation programmes, screening and brief intervention with family support, and home-based programmes have demonstrated positive outcomes in reducing the use of tobacco, alcohol and khat, respectively. ^{Reference Sinha, Kohli, Ghosh and Basu31,Reference Widmann, Apondi, Musau, Warsame, Isse and Mutiso34,Reference Castaldelli-Maia, da Silva, Campos, Moura, Zabert and Champagne38} However, the heterogeneity in outcomes, study designs and target populations made it difficult to draw concrete conclusions regarding the optimal type, mode, dosage and characteristics of psychosocial interventions for individuals with severe MHCs and co-occurring SUDs.

The feasibility and acceptability of the promising tobacco cessation programmes were largely limited to psychosocial care units. Various forms of CBT, such as brief CBT and mindfulness-based CBT, also demonstrated feasibility and acceptability in reducing depressive symptoms, addressing alcohol dependence and preventing substance relapse in settings like Iran and Thailand. Despite these successes, such interventions often required significant resources, including more trained healthcare providers, limiting their applicability in very low-resource settings. ^{Reference Zemestani and Ottaviani28,Reference Thapinta, Skulphan and Kittrattanapaiboon33}

The existing evidence was mostly limited to tobacco and alcohol. However, psychostimulants like khat, which were more prevalent in some low-resource contexts such as East Africa, pose additional challenges for individuals with severe MHCs. ^{Reference Odenwald, Lingenfelder, Peschel, Haibe, Warsame and Omer29} Odenwald et al highlighted that although community-based interventions for psychosis were both feasible and acceptable in Somalia, challenges such as limited local capacity and comorbid khat use persisted. Therefore, adapting suitable interventions for people with severe MHCs and comorbid SUDs to low-resource settings remains critical.

There is an urgent need to promote guidelines for the screening and treatment of people with severe MHC and SUDs to achieve better outcomes, as concurrent disorders are often underdiagnosed, undertreated and more complex to manage. ^{Reference Hakobyan, Vazirian, Lee-Cheong, Krausz, Honer and Schutz41} However, the current review found only one guideline from the Brazilian Association of Studies on Alcohol and Other Drugs (ABEAD) for the diagnosis and treatment of psychiatric comorbidity with alcohol and other substance dependence, which clearly described the scope and purpose of the guideline. ^{Reference Zaleski, Laranjeira, Marques, Ratto, Romano and Alves39} Additionally, there was a study on the adaptation of an app to screen for dual disorders, which shows promise as a useful screening tool in residential addiction treatment centres.³⁷ Previous global reviews identified 23 other guidelines, all of which were from HICs. ^{Reference Hakobyan, Vazirian, Lee-Cheong, Krausz, Honer and Schutz41} The World Health Organization’s mental health Gap Action Programme Intervention Guide (mhGAP-IG 3.0) does not include specific interventions for the prevention and management of comorbidity between SUDs and severe MHCs. However, it recognises the detection of tobacco, alcohol and substance use among people visiting health facilities, and has potential for adaptation for people with severe MHCs. ⁴² Universal screening for substance use in individuals with severe MHCs appears ethically and scientifically justified. However, it should be preceded by the development and evaluation of effective interventions. Therefore, addressing both severe MHCs and SUDs concurrently should be a priority.

This review also underscores inequities in healthcare provision for individuals with severe MHCs and SUDs. ^{Reference Druss and von Esenwein43} For individuals with severe MHCs and SUDs, even minimal substance use can have far-reaching consequences. ^{Reference Hunt, Malhi, Cleary, Lai and Sitharthan17–Reference Najt, Fusar-Poli and Brambilla20,Reference Smartt, Ketema, Frissa, Tekola, Birhane and Eshetu44} Although not considered in this review, comorbidities like HIV/AIDS, hypertension, diabetes and cardiovascular diseases are often prevalent in this population, ^{Reference Lee, McKibbin, Bourassa, Wykes and Andren21} which underlines the need for a person-centred approach. Poor health outcomes in these populations can be attributed to barriers such as limited access to quality healthcare and routine screening, stigma from healthcare providers and a lack of knowledge about comorbid conditions. In some cases, substance use or physical health issues are overlooked or misinterpreted in individuals with severe MHCs, further complicating their treatment. ^{Reference Mitchell, Malone and Doebbeling45,Reference Van Boekel, Brouwers, Van Weeghel and Garretsen46}

The current study identified group therapy, CBT, brief interventions and MBRP as feasible psychosocial interventions in LMICs, in addition to psychosocial rehabilitation. In contrast, HICs have developed and tested a broader range of well-adapted psychosocial interventions for individuals with severe MHCs and SUDs. ^{Reference Hunt, Siegfried, Morley, Brooke-Sumner and Cleary22} However, a Cochrane review indicated no clear superiority in efficacy among various psychosocial interventions – including CBT, motivational interviewing, case management, skills training and contingency management – either relative to each other or compared with treatment as usual. ^{Reference Hunt, Siegfried, Morley, Brooke-Sumner and Cleary22} Although many psychotherapeutic approaches incorporate elements of motivational interviewing, ^{Reference Miller and Rollnick47} evidence does not support its superior efficacy over other methods. ^{Reference Hunt, Siegfried, Morley, Brooke-Sumner and Cleary22} Some interventions, such as assertive community treatment and token economy approaches, require substantial resources and may not be practical in LMICs settings. In contrast, low-resource interventions, such as motivational interviewing, psychoeducation and peer support, appear more promising. Additionally, many randomised controlled trials targeting severe MHCs exclude individuals with co-occurring substance use, thereby limiting the generalisability of their findings to dual diagnosis. ^{Reference Mihretu, Nhunzvi, Fekadu, Norton and Teferra48}

We also found that cultural use of certain substances, such as khat, which is not widely recognised as an SUD, may be overlooked in studies of dual diagnosis. ^{Reference Mihretu, Nhunzvi, Fekadu, Norton and Teferra48} Khat is a stimulant with amphetamine-like properties, ^{Reference Feyissa and Kelly49} commonly used in East Africa and among diaspora communities in Europe. ^{Reference Ongeri, Kirui, Muniu, Manduku, Kirumbi and Atwoli50,Reference Bhui and Warfa51} Its use has been significantly associated with elevated rates of psychotic symptoms. At least one psychotic symptom was reported by 16.8% of khat users. ^{Reference Ongeri, Kirui, Muniu, Manduku, Kirumbi and Atwoli50,Reference Babor52} Psychosis has been particularly linked to heavy or prolonged khat use and may also exacerbate pre-existing MHCs. ^{Reference Babor52–Reference Warfa, Bhui, Craig, Curtis, Mohamud and Stansfeld54} Khat use disorder has also been recognised as a valid diagnostic entity. ^{Reference Duresso, Matthews, Ferguson and Bruno55} Khat use disorder meets the core diagnostic criteria for stimulant use disorder as outlined in the DSM-5. These include impaired control over use, significant social and occupational harm, and characteristic withdrawal symptoms such as depressed mood, irritability, fatigue, lack of motivation, hypersomnia and increased appetite. ^{Reference Mihretu, Nhunzvi, Fekadu, Norton and Teferra48,Reference Mihretu, Fekadu, Norton, Habtamu and Teferra56}

The methodological quality of the studies included in this review was a concern. Many studies employed non-randomised, uncontrolled experimental designs, which come with high risk of bias. ^{Reference Andrade57} Some of the randomised controlled trials were underpowered to detect changes in the outcomes. ^{Reference Asher, Hanlon, Birhane, Habtamu, Eaton and Weiss40} Although better-powered studies may reveal significant differences, it might still be important to consider the clinical significance of the existing findings as they stand. This further highlights the need for more rigorous research on dual diagnosis in LMICs. In contexts like Ethiopia, where this review was conducted, designing and implementing psychosocial interventions presents challenges, including limited human and material resources. However, contextual adaptation of these interventions remains feasible.⁵⁸