Coping mechanisms such as tobacco smoking, excessive alcohol consumption, poor diet, and physical inactivity are common behaviours among people with SMI [5], many who consider these a consequence of trying to manage their mental illness. These risky behaviours contribute to the high rates of chronic physical illnesses, the most common being CVD [1]. A clear association between SMI and CVD identifies that the comorbidity of these chronic conditions has a shared biological (older age, male gender, family history), psychological (stress, major depression) and lifestyle (smoking, alcoholism, poor diet, lack of exercise) aetiology [8]. Further, a person with SMI typically experiences a combination of three main symptom types across the course of their illness: positive (delusions and hallucinations), negative (amotivation and anhedonia) and cognitive symptoms (poor concentration, reasoning and memory) [9]. The influence of these symptoms and their interaction severely impact the day-to-day activities of people with SMI, making it difficult for them to manage their mental and physical health effectively.

Besides the bio-psychological and lifestyle-related risk factors linking SMI and CVD, common socio-environmental factors such as financial hardship, lack of access to community resources, and social isolation appear to perpetuate the comorbidity of these conditions [10]. Researchers have observed that the nature and complexity of the SMI-related symptoms (disorganised behaviours, major depression and anxiety, cognitive impairment, problems with social skills) often lead to high rates of unemployment, underpinning the financial hardship among people with SMI [11]. Financial hardship frequently impacts this group’s capacity to access transportation and maintain consistent housing or accommodation [12]. The unpredictability or absence of housing and transport can disengage individuals with SMI from their community, diminishing their overall quality of life.

Social support is another crucial protective factor known to improve the overall health of people, especially those living with mental–physical health comorbidity [4]. Due to the complexity of SMI and related positive symptoms (delusions, hallucinations), it is not unusual for this population to experience significant social stigma, self-stigma, social exclusion and isolation [13]. As a consequence, people with SMI may be more prone to live in unsafe environments that expose them to greater risks of substance abuse such as heavy smoking, alcoholism and drug misuse [11,12], contributing to the likelihood of CVD. In addition, due to the ongoing social stigma towards mental illness, service users may struggle to fully engage and participate in, or gain equitable access to, meaningful community activities as citizens. The combination of the aforementioned factors, the debilitating nature of SMI and the potential low physical health literacy, has created further challenges for this population in managing their health conditions [14]. Ultimately, these circumstances are implicated in reducing self-esteem, negatively impacting their treatment-seeking, and delaying the delivery of effective prevention, early intervention and treatment for their health conditions [15].

Health system-centric factors increasing the risk of CVD among those with SMI include inconsistency in the provision of quality medical care tailored for this population group. For instance, General Practitioners (GPs) are well-positioned to promote healthy lifestyles in people with SMI [11]. However, evidence suggests that feeling stigmatised in a primary health care setting, coupled with GPs’ lack of experiences in managing people with SMI, is likely to undermine help-seeking behaviours and adherence to treatment plans recommended by GPs [13]. Consequently, some researchers have argued that physical healthcare should be the responsibility of mental health professionals (particularly psychiatrists and mental health nurses), owing to their existing expertise with this group [16]. However, both internationally and in Australia, the major shift of psychiatry towards ‘deinstitutionalisation’ and ongoing reforms have overburdened the mental health system [2]. Similarly, structural changes in primary and secondary care have led to increased levels of bureaucracy and increased pressure on already scarce health resources (insufficient skilled staff and time), creating further challenges for SMI populations to access GPs’ services [10,17]. There are ongoing dilemmas regarding who is well-suited and responsible for managing the physical health needs of people with SMI [18]. Furthermore, where there are clear guidelines on how to identify and manage physical health risk factors among people with SMI, health policies and procedures are poorly implemented; here, Australia is no exception [18]. As a consequence, people with SMI have limited access to preventative care, motivational interventions and evidence-based guideline-concordant treatments that address both lifestyle risk-factors and physical illnesses such as CVD [19].

Although there are strong signals identifying an association between CVD and SMI risk factors, person-centred evidence-based healthcare (EBHC) interventions relating to CVD-risk reduction strategies are rare [20]. Recovery-oriented and self-management-based interventions, tailored information, education and training incorporating community support are considered crucial for potentiating physical health for this population [21]. Research has indicated that, when these interventions are implemented, better health outcomes are observed owing to the approach enhancing individuals’ abilities, knowledge and confidence to manage their conditions [22]. Furthermore, the provision of a person-held medical record has been proven to improve the knowledge of physical health risks among those with SMI [23]. A person-centred approach to healthcare acknowledges the important contributions of the families of people with SMI to care decisions and support, and emphasises partnership and collaborative interventions. Peer support, and clear and brief health promotion messages are well suited to this population [24]. In practice, however, most of these elements are overshadowed within predominantly hierarchical healthcare systems primarily interested in maintaining acute care, risk and medication compliance, with least focus on the long-term holistic psychosocial wellbeing and needs of this population [25,26]. This ‘illness’ focus is notably at odds with a recovery-orientation [27,28].

Health service culture can also negatively impact the uptake of recovery-oriented and self-management-based physical health interventions specific to the SMI population [27]. Broadly, among mental health organisations, there is a service culture perception that improving physical health behaviours among SMI persons is highly challenging [23]. This cultural inertia includes the acceptance of obesity as an inevitable side-effect of antipsychotic medications [29]. Similarly, smoking by people with SMI continues to be considered as an embedded culture or group norm within mental health services [30]. Thus, pervasive pessimism regarding the capacity of people with SMI to embrace health behaviour change contributes to the failure to treat these common CVD risk factors among people with SMI [31]. Nevertheless, evidence shows that changes in mental health organisational culture can be accomplished with targeted improvement strategies [32]. Such improvement strategies targeting culture can concentrate on the major impeding factors, such as an absence of strong clinical leadership and engagement, and a lack of coordination in inter-organisational partnerships and teamwork [33]. However, the implementation of the aforementioned approaches meets consistent resistance from the mental health system, as novel strategies are often considered a threat to extant rules and regulations; thus, both fail to be initiated and subsequently sustained [33].

Beyond health system-level cultural issues, models of practices (e.g., individually based illness model vs. recovery approach) also influence treatment methodologies, and are seen as problematic among mental health researchers [27,34]. For instance, to date, psychiatry heavily relies on a medication-centric model, although research has repeatedly showed the adverse impacts of a variety of these drugs on people’s overall health and wellbeing [35]. It is also important to note that some of the CVD-related risk factors themselves may be the ‘iatrogenic (inadvertently induced and often harmful) consequences of antipsychotic medications’ [36]. These include, for instance, amplified appetite that is driven by some of the antipsychotic medications, resulting in negative impacts on metabolism and rapid weight gain [35]. Sedation and other common side-effects of antipsychotic medications can also hinder the person’s motivation and energy to make healthy lifestyle choices [26]. Adding further complexity, for some people with SMI, these antipsychotic medications are ‘imposed coercively’, with limited collaborative decision-making with the person about medication choice and dose, as part of them being detained for in-person treatment, or as part of compulsory Community Treatment Orders (CTOs) [34]. As Laugharne and Priebe [37] found, this issue of power imbalance between persons and clinicians was identified as a contributor to people with SMI disengaging from mental health services. A recent Cochrane review found that CTOs did not result in improved service use, social functioning or quality of life compared to voluntary care [38]. However, the authors acknowledged that the findings were inconclusive due to the small number of articles. Despite the findings, it is important to note that coerced treatment inhibits active engagement by the person in their care [39], and damages their trust in healthcare providers [40], known to be crucial in improving overall health outcomes [41]. The provision of correct and sufficiently communicated information, treatment choice, continuity of care and a consistent attending clinician are deemed critical components to enable people to retain trust in mental health service systems [37,42].

The acknowledgement of the acceptability and potential clinical effectiveness of integrated general medical and psychiatric care interventions has led to policymakers recently reorienting towards the adoption of recovery-oriented EBHC programmes within the mental health system [13]. However, Hannigan and Coffey [43] noted a paradox: the act of such an implementation has created further challenges by initiating a variety of top-down interventions without considering how delivery will be achieved in different contexts. Similarly, another major disconnection is between the research sector and community health practices, resulting in the poor translation of EBHC within real-world settings [44]. To ensure effective physical health outcomes in people with SMI, research will need to align with policy priorities that are fully informed by the practice field. To achieve this alignment, research and policy makers will need to understand the practical challenges faced by frontline clinicians such as psychiatrists, mental health nurses, and GPs [13]. Of further concern is that current EBHC research is predominantly focused on ‘biomedical’ self-management and related individualistic factors. Biomedical self-management involves both ‘work’ and ‘cost’ for persons, where the management burden is often shifted from the health care system to the person [22,45]. This contrasts with ‘lifeworld’ self-management and related research, which additionally considers socio-environmental factors, where the problems originate and are sustained [45].

Existing research also suggests that outcome evaluation alone is generally inadequate to address wicked problems (problems that are often resistant to change or improvement initiatives) [46], as with those highlighted in this review. A naturalistic study investigating health settings from both ‘inside’ and ‘outside’ is needed to examine the lifeworld implementation of EBHC and self-management-based interventions in community mental health settings [45]. Few studies have represented a holistic picture of the factors that impact and shape the uptake of chronic condition self-management (CCSM) behaviours and related health practices [45,47]. While progress may be made by employing person-centred physical health interventions [44], it often fails to achieve replicability and sustainability due to the poor understanding of underlying processes facilitating or impeding the delivery of these interventions in the first place [48]. The status quo reflects the clear paucity of research into the successful implementation of person-centred physical health interventions among people with SMI.