JESS TO INSERT UPDATED EXCEL TABLE HERE RELATING TO INTERVENTIONS FOR PEOPLE LIVING WITH CHRONIC CONDITIONS, SPANNING MULTIPLE DOMAINS OF WELLBEING. THIS WILL BE A VERY IMPORTANT TABLE FOR FIELDBAY PROJECT.
Well-being Domains Potential Intervention Considerations & Potential Barriers
Individual Facilitating positive health behaviours (including dietary changes \citep{Opie_2015,Singh_2017,Owen_2017}, increasing physical activity levels \cite{Warburton_2006} , improving sleep cycles  \citep{Kato2009}, smoking cessation, minimal alcohol consumption \citep*{Room_2005}. Difficulties associated with behaviour change \cite{Sheeran_2002}. Sociostructural issues (e.g. SES, inequality, community cohesion) will impact on capacity to engage fully in positive health behaviours [REF?].
Positive psychology activities including 'three good things' writing, gratitude visits, strengths-based activities, meditation, logotherapy (to build meaning & purpose) Due to individual charactersitics the suitability of activities will depend on the patient group to which therapy is directed, e.g. XXX [REF]. Reminiscence therapy may have short-lived cognitive benefits; however  the effects of reminiscence interventions are inconsistent, often small in size and can differ considerably across settings and modalities \citep*{Woods_2018}.           
Reminiscence therapy to stimulate the senses
Community Group-based positive psychotherapy XXX
Animal assisted therapy May increase instances of arousal and distraction; though this does not necessarily interfere with concentration levels \citep*{Gocheva_2018}. Concern surrounding cost-effectiveness; especially in instances of Equine involvement \citep*{Charry_S_nchez_2018}
Choir XXX
Walking football XXX
Environmental
Forest bathing
Barriers include transport to location (could be combatted by VR and changing immediate environment), weather, client mobility, availability of supporting staff and risk assessment
Gardening; responsibility to look after a plant Relevant to the biophilia hypothesis, ‘positive psychology of sustainability’ and ‘sustainable happiness’
Environmental changes, e.g. lighting, greenery, nature-based wallpaper, temperature changes, nature sounds Potential barrier includes available funding
5.1 Promoting Health and Wellbeing in Individuals
Our theoretical models emphasise a cycle of mutually causal factors including healthy vagal function, positive psychological moments, health behaviours and social relationships which trigger a cascade of downstream physiological processes that will facilitate pathways to individual health and wellbeing (Kemp et al, 2017). Accordingly, in this section we provide evidence linking each of the factors identified as being critical in facilitating pathways to individual health and wellbeing, in the aetiology of chronic conditions as well as highlighting their potential to be targets for prevention and treatment. 
  
5.1.1: Health Behaviours 
Health behaviours (including poor diet, physical inactivity) are now known to be the main environmental factors in the increasing prevalence of chronic conditions. Negative health behaviours are thought to contribute to the pathogenesis of chronic conditions through immune pathways which trigger a cascade of downstream effects on insulin resistance, cardiovascular disease, obesity and psychological functioning. Accordingly, the health and wellbeing of people living with chronic conditions may be supported and improved by focusing on interventions to facilitate positive changes in health behaviours (Lassale et al., 2019; Dinu et al., 2018; Lee et al., 2012). The World Health Organisation (http://www.who.int/chp/chronic_disease_report/en/) estimate that at least 80% of premature heart disease, stroke and type 2 diabetes, and 40% of cancer could be prevented by regular physical activity, a healthy diet and smoking caseation.
 
In this section we review some of the evidence implicating unhealthy behaviours in the pathogenesis  and the exacerbation of chronic physical and mental health conditions. We then explore, at the level of the individual, evidence exploring whether improving health behaviours can prevent or ameliorate chronic conditions. For the sake of brevity, given the number of health behaviours, we focus predominantly on physical exercise, diet and sleep. 
 
Physical Activity: It is estimated that physical inactivity is responsible for between 10-11% of the burden of chronic disease (Carlson et al., 2015), including diabetes, colon cancer and coronary heart disease, and that inactivity causes 9% of premature mortality (Lee et al., 2012a). Physical activity favourably impacts on a variety of physical health outcomes including improved autonomic function (Adamopoulos et al., 1992), reduced abdominal adiposity (Tremblay et al., 1990) and reduced systemic inflammation (Adamopoulos et al., 1992). This has been shown to result in decreased risk of all-cause and cardiovascular-related death, diabetes mellitus and cancer (Warburton et al., 2006), providing a basis on which its prescription may be used as a treatment for many chronic diseases to improve symptoms. Regular physical activity can be an effective primary and secondary preventative measure for at least 25 chronic conditions (Rhodes et al., 2017), along with improving cognitive function, an especially important consideration given that chronic conditions are associated with declining cognitive ability (Lautenschlager et al., 2008), an important contributing factor to ill-health and illbeing (Brosschot 2017, Beauchaine 2015, Friedman 2007).  
 
Targeting exercise to prevent or ameliorate the impact of chronic conditions and mental health conditions: Physical activity has proven effective in symptom reduction as part of treatment for many chronic conditions or mental health conditions which often co-occur with, with, and exacerbate the impact of, chronic physical conditions, including anxiety (Aylett et al., 2018; Oeland et al., 2010), depression (Rimer et al., 2012; Weyerer, 1992), schizophrenia (Girdler et al., 2019; Vancampfort et al., 2012), panic disorder (Hovland et al., 2013), PTSD (Liedl et al., 2011), bipolar disorder (Kucyi et al., 2010), binge eating disorder (Pendleton et al., 2002), bulimia nervosa (Sundgot-Borgen et al., 2002), anorexia nervosa (Zunker, Mitchell, and Wonderlich, 2011), and substance use disorders (Ussher et al., 2014; Smith et al., 2011). Epidemiological research has demonstrated a strong association between mental health and aerobic exercise (for a comprehensive review see Biddle, 2000). In the German National Health Interview and Examination Survery from 1999 to 1999 including 7,124 participants, Schmitz, Kruse, and Kugler (2004) explored the association between physical activity and health related quality of life. The reported that higher levels of physical acitivty were associated with higher quality of life for participants with affective, anxiety, and substance dependence disorders. Conversely, Goodwin (2003) showed an association between physical inactivity and major depression and anxiety disorders in a clinical population. In their meta-analysis, Stathpoulou and Power, (2006), explored the efficacy of exercise in a clinical population of people with depression across 11 treatment outcome studies including 513 participants. The reported a very large combined effect size for exercise verses a control group. Based on their findings the authors concluded that clinicians should consider the prescription of exercise in their clinical practice.
 
Diet: There is now compelling evidence suggesting that main environmental risk factors implicated in the increasing instances of chronic conditions and mental health conditions is attributable to poor diet and sedentary behaviour (Booth, Roberts, Layne, 2012). It is thought that diet and physical inactivity may exert their effects through immune pathways, with subsequent downstream effects on cardiovascular disease, insulin resistance, obesity, as well as mood and behaviour (reference). Diet has been implicated in the aetiology of several chronic conditions. For example, a high intake of saturated fatty acids is a risk factor for impaired glucose tolerance and diabetes (\citep{Storlien_1996}). The Nurses’ Health Study showed diabetes was associated with diets containing a high glycaemic load and low cereal fibre \cite{Salmerón1997}
 
Accordingly, targeting the diet of individuals may help to prevent or ameliorate the impact of chronic conditions and mental health conditions. In the next section we review evidence exploring the effect of a healthy diet on prevention and treatment of chronic conditions. However, before doing so it is worth making several critical points. First, when considering the effect of diet on health it is essential that a life course view is taken (Darnton-Hill, Nishida and James, 2004). For example, it is now well established that risk factors for diseases typically associated with poor diet (obesity, cardiovascular disease, diabetes) can begin during fetal development (WHO, 2002; Ben-Shlomo Y, Kuh, 2002), childhood or adolescence. In fact, some research has indicated that early risk factors may act across generations (see Darnton-Hill et al, 2004 for a review). Accordingly, there may be critical periods across the life course where exposure to healthy or unhealth diet my increase or decrease the risk of subsequent disease (r Darnton-Hill, Nishida and James, 2004). The timing of interventions regarding diet should therefore be sensitive to such critical periods. For example, children who are breast fed have been shown to have lower blood pressure in childhood (Wilson, Forsyth, Greene, Irving, Hau, Howie, 1998; Singhal, Cole, Lucas, 2001) and lower risks of developing obesity (Kramer, 1981; von Kreis, Koletzko, Sauerwald, von Mutius, Barnert, Grunert, 1999; von Kreis R et al, 2001). Mann (2002) highlighted the importance of the adult phase of life as a critical time in the prevention and reduction of risk factors and as a critical stage in treatment efficacy.
 
A second critical point, which will be picked up in section 5.3?? of this review, is that interventions designed to improve diet in order to prevent or ameliorate the impact of chronic conditions must be implemented at an community and governmental level as well as an individual level. Such interventions must be particularly targeted toward those in with lower socioeconomic status.
 
Targeting the diet of individuals may help to prevent or ameliorate the impact of chronic conditions and mental health conditions: In an extensive review, Kromhout (2016) concluded that consumption of vegetables and fruit convincingly reduced the risk of coronary heart disease (CHD) and stroke, and on this basis the Dutch food-based dietary guidelines recommended at least 200g of vegetables and 200g of fruit per day.  (Kromhout 2016). This is in keeping with the NHS guidelines which recommends 'five-a-day' (or 400 grams) (UKGOV, 2019), as well as guidance from the World Health Organisation (WHO | Promoting fruit...). Kromhout (2016) also concluded that the consumption of nuts convincingly reduces CHD risk and recommended that one eats at least 15 grams of unsalted nuts per day, although this is not currently recommended in UK guidelines. Also recommended was the consumption of 90 grams of brown or whole-grain products daily, as whole-grain products has been shown to reduce risk of CHD. In contrast to the recommendations by Kromhout et al. (2016), other research suggests that as many as 'ten-a-day' may be required for long-term health benefit (Aune 2017).  Recent studies have demonstrated that the Mediterranean diet may protect against chronic disease including common mental disorders (Lassale et al., 2019; Dinu et al., 2018)Sofi et al. (2010) concluded from a systematic review and meta-analysis that a greater adherence to a Mediterranean diet leads to a significant reduction in cardiovascular incidence, cancer incidence or mortality and neurodegenerative diseases. Importantly, randomised controlled trials now demonstrate that adopting a Mediterranean diet independently reduces cognitive decline associated with chronic conditions (Martínez-Lapiscina et al., 2013; Valls-Pedret et al., 2015). Dietary changes have shown to be effective in triggering changes in the intestinal microbiome (a modulator in the risk of disease development) within 24 hours, highlighting the importance of diet as a pathway through which health can be improved (Singh et al., 2017). It is argued that targeting diet would be an effective opportunity to relieve the growing burden of mental and neurological disease (Owen and Corfe, 2017).  This may seem common knowledge, but it has been well established that ‘common knowledge is not common action’ (Swan 2014). For example, a study by Bell et al. (2015) showed that 20% of nursing home residents have been reported to be malnourished internationally, although depending on the definition of malnutrition prevalence ranges from 1.5% to 66.5% (Bell, Lee, and Tamura, 2015). Studies have also shown that improved diet can be effective in improving depression symptomology (Opie et al., 2015; Parletta et al., 2019). An important dietary contributor to risk of future chronic illness is alcohol consumption, which has been causally related to 60 medical conditions, including certain cancers (breast, mouth and liver), epilepsy and haemorrhagic stroke (Room, Babor, and Rehm, 2005). In ‘The 2015 Dutch food-based dietary guidelines’ (Kromhout 2016) claimed that alcohol convincingly increases the risk of stroke and that binge drinking 60 g or more significantly increases the risk of CHD and thus recommends that individuals abstain from alcohol all together or do not drink more than one glass daily. This is roughly in line with the NHS guideline (NHS, 2019) which recommends no more than 2 units a day (this is roughly one pint of beer or a glass of wine). There is mixed evidence as to whether there is a ‘J’ shaped relationship between alcohol and all-cause mortality such that drinking a low amount of alcohol may be more beneficial for health than abstaining from alcohol all together. However, a meta-analysis of 87 studies (Stockwell 2016) adjusted results to account for abstainer bias towards ill health and found no significant reduction in mortality risk for low volume drinkers compared to those who abstain from alcohol. Including former drinkers in the abstainer reference group has biased the drinking risk estimates in many studies. Thus according to these findings, it is best to abstain from alcohol all together as one cannot not assume there are health benefits to low level drinking. It is acknowledged however, there are other reasons people consume alcohol (e.g. social drinking) and that risk increases with amount drunk.
 
Sleep:  Sleep is an important factor influencing the health and wellbeing of people living with chronic conditions. The International Classification of Sleep Disorders includes more than 80 sleep disorders. Sleep disorders are associated with increased risk of all-cause mortality and serious adverse health consequences (Alvarez et al., 2004). Epidemiological studies have shown that people with chronic conditions (eg. heart disease, arthritis, diabetes, stroke and lung diseases) had a significantly higher incidences of sleep disturbances than those without such conditions (Foley et al., 1999)(Maggi et al., 1998)(Vitiello 1997)(Foley et al., 1995),  (Ancoli-Israel et al., 1991)(Foley 1999),  (Whitney et al., 1998),  (Newman et al., 1997) and (Enright et al., 1996).  The relationship between many chronic conditions and sleep has been shown to be bidirectional; the worsening of one can influence the other (Lee 2012, Ancoli-Israel 2006). Overall there is compelling evidence of the contribution of sleep disorders to the pathogenesis and exacerbation of chronic conditions. In this section we illustrate this point with several examples for the purpose of brevity. We then present evidence exploring the treatment of sleep disorders or they underpinning moderators, which may have the potential to ameliorate the impact of chronic conditions.
 
Two of the most prevalent sleep disorders, Insomnia and OSA have been shown to contribute to an increased risk of several chronic health conditions ((Hargens, Kaleth, Edwards, and Butner, 2013) including, but not restricted to, diabetes mellitus (Punjabi et al., 2004) and cardiovascular disease (Somers 2008), asthma (Janson et al., 1996), systemic lupus erythematosus (Gudbjörnsson et al., 2001), rheumatoid arthritis (Luyster et al., 2011) and inflammatory bowel disease (Keefer et al., 2006). The mechanisms which underpin this relationship are complex and many. However, it is thought that most common sleep disorders result in a reduction of sleep quality and duration which has been associated with increased body weight and adiposity, potentially leading to obesity (López-García et al., 2008)(Patel et al., 2008). Although obesity has not yet been classified as a chronic condition in its own right in the UK, it has been formally recognised as such in the United States (references). Nonetheless, it has been well established that obesity significantly contributes to the pathogenesis of many chronic conditions. Consequently, it has been argued that the relationships between chronic conditions and sleep disorders are likely mediated by obesity. For example, with respect to insomnia, Taheri et al. (2004) showed that shorter sleep durations were associated with 15% lower lepin levels and 14.9% higher ghrelin levels which were independent of Body Mass Index (BMI). They concluded that chronically shortened sleep duration could increase appetite leading to overeating and eventually obesity. The neuro-cognitive theory of insomnia suggests that insomnia is associated with increased levels of cortisol (Perlis et al., 1997)Dallman et al. (2003), proposed that chronic evaluation of gluocorticoids, such as cortisol may be implicated in the overconsumption of high fat and sugary foods and the propensity to store fat around the abdominal area. They argue that chronically elevated levels of glucocortical hormones increase  corticotropin-releasing factor activity in the central nucleus of the amygdala which increases stimulus salience and abdominal obesity. This mechanism then moderates metabolic inhibitory feedback on the catecholamines in the brain and the expression of corticotropin-releasing factor. Accordingly, the authors propose that, in an attempt to dampen activity in the brain,  the same mechanisms which mediates hyperactivity in insomnia facilitates overconsumption of high fat and sugary foods as well as promoting abdominal obesity. 
 
Population studies have also demonstrated a strong associated between OSA and chronic diseases including cardiovascular disease, hypertension, diabetes mellitus and stroke (Somer et al, 2008) (Kato et al., 2009). Moreover, as with insomnia, a strong relationship has also been shown between OSA and obesity and emerging evidence suggests a reciprocal interaction (Passos et al., 2010)(Malhotra et al., 2002).  Ong et al. (2013) propose that obesity causes changes to the upper airway structure and function, causes 'reductions in resting load volume and negative effects on respiratory drive and load compensation' compensation' (Hargens et al., 2013).  Several studies (Marshall 2002)(Bryant 2004) have highlighted the reciprocal relationship between sleep and the immune system whereby sleep disturbances affect immune function (Born et al., 1997) (Everson, 1993) and activation of the immune system disturbs sleep patterns (Späth-Schwalbe et al., 1998)(Takahashi et al., 1999). Thus sleep disturbance may be linked directly to the pathogenesis of chronic inflammatory conditions such as asthma, rheumatoid arthritis and inflammatory bowel disease. For example, sleep disturbances are one of the major modifiers of asthma and can directly affect its course and severity. Specifically, sleep disturbances have been shown to negatively affect respiration, arousal responses and airway clearance (DAmbrosio et al., 1998). This effect is thought to be underpinned by prolonged supine posture, intrapulmonary pooling of blood, alterations in balance between the parasympathetic and sympathetic nervous system, sleep induced reduction in lung volumes (Ballard, 1999)
 
Another significant factor which may mediate the relationship between chronic conditions and sleep disorder is pain. It has been shown that chronic conditions associated with pain are associated with a higher prevalence of sleep disorders than conditions that are not (Benca et al., 2004). Although the relationship between pain and sleep remains unclear (Drewes et al., 2019) (Roehrs et al., 2017; Roehrs et al., 2005), some have suggested that pain has an arousal-enhancing effect that prevents the initiation and/or maintenance of sleep. Others argue that pain and disturbed sleep are underpinned by common neurobiological pathways and that poor sleep negatively affects pain processing causing increased pain sensitivity (Moldofsky, 2001)(Smith et al., 2004) (LAUTENBACHER et al., 2006). Again, there is evidence of a reciprocal interaction between sleep and pain with disturbed sleep increasing pain sensitivity  and with pain sensitivity decreasing following deep, less fragmented sleep (Bigatti et al., 2008)
In sum, the examples above illustrate how sleep disturbances may be implicated in the pathogenesis of a range of chronic conditions either by exerting their effects directly (e.g. via the immune system) or indirectly (eg. increase appetite leading to overeating of unhealthy food). Moreover, example also show how sleep disturbance can exacerbate the impact of chronic conditions (for example by increasing pain sensitivity). To further illustrate this point with cardiovascular diseases as an example, insomnia has been shown to reduce compliance with anti-hypertensive and other cardiovascular medications (Haaramo et al., 2013). Moreover, the presence of insomnia also predicted the development of cardiovascular  conditions including cardiovascular disease (Sands-Lincoln et al., 2013) and myocardial infarction  (Laugsand et al., 2013), independently of traditional risk factors (Spiegelhalder, Scholtes, Riemann, 2010). This evidence points to importance of identification of sleep disturbances in people with chronic conditions and also suggests the important of treatment of either the sleep disorder its self or its moderating factors (e.g weight gain, pain).
 
Targeting sleep may help to prevent or ameliorate the impact of chronic conditions and mental health conditions: Cognitive Behavioural Therapy has been shown to be an effective treatment for adults with insomina with clinically meaningful effect sizes (Trauer et al., 2015).   Music  therapy has proved effective for both acute and chronic sleep disorders (Wang, Sun, and Zang, 2014), with massage, acupuncture, natural sounds and music videos being reported to be effective in health care settings (Hellström and Willman, 2011).  As discussed above physical activity is often recommended for obesity. Given the reciprocal interaction between obesity and sleep physical activity has also been explored for the treatment of sleep disorders. Interestingly, in several cross sectional studies physical inactivity has been shown to be a risk factor for poor sleep and insomnia (Chasens et al., 2012)(Paparrigopoulos et al., 2010)(Foley 2004)(Morgan, 2003). With respect to insomnia, physical activity has been shown benefit people with sleep disorders but this was dependent but this was dependent on the type and intensity of the physical activity, with moderate-intensity aerobic exercise proving beneficial as opposed to high intensity aerobic and moderate-intensity resistance training  (Passos et al., 2010). A plethora of studies have also shown amelioration of OSA and associated symptoms such as excessive daytime sleepiness as a function of increased physical activity and/or diet (Tuomilehto et al., 2009)(Tuomilehto et al., 2013)(Kuna et al., 2013)(Foster et al., 2009).
 
Health Behaviour Conclusion: INSERT CONCLUDING PARAGRAPH – plus:
 
 
It is noted however, that simply providing information on modifications to health behaviours is not sufficient to elicit behaviour change. The use of behaviour change theory or behaviour change techniques is needed (Michie, Fixsen, Grimshaw, and Eccles, 2009), such as self-monitoring, goal setting, goal review and feedback; proving to increase the likelihood of behaviour change (Michie et al., 2009). Based on the upward spiral theory of lifestyle change, increasing positive affect will encourage adherence to a new behaviour change (Van, Rice, Catalino, and Fredrickson, 2018), mediated by increasing HRV and social connectedness (Kok and Fredrickson, 2010). There is a need to build positive psychological experiences in parallel with the ongoing medical treatment to both increase treatment adherence and improve health and wellbeing through other routes.
5.1.2: Positive Psychological Moments/experiences: 
Our theoretical models outline mechanisms by which psychological experiences can, if positive, facilitate individual pathways to health and wellbeing and if negative, facilitate pathways to ill-health and premature mortality (Kemp, Arias, & Fisher, 2017a; Kemp, Koenig, & Thayer, 2017b). Our models provide extensive evidence that psychological experiences, alongside genetics, environmental influences and their interactions (epigenetic processes), play a critical role in the aetiology of mental and physical health conditions via a range of downstream allostatic processes (see Kemp et al, 2017 for a comprehensive review). In our updated GENIAL model we use the term ‘psychological experiences’ to refer to an individual’s interpretation of life events and the temporal narrative relating to the events over one’s life course via cognitive and emotional processes.
 
It is generally accepted that biology, the environment, adverse life events, personality and psychological attributions are all important in understanding the aetiology of mental health problems [Engel, 1977]. For example, genetical abnormalities have been implicated in the aetiology of mental health disorders (Sullivan, Neale, Kendle, 2000), coupled with the ‘additive’ effects of negative life events and environmental factors (Guze, 1989) which all negatively affect psychological functioning (Van Os, Kenis, Rutten, 2010). In terms of psychological experiences, much literature indicates that reasoning abilities, thinking styles and behaviour are critical in the aetiology and maintenance of mental health conditions (Kinderman, 2005). However, some authors have argued that psychological factors are the ‘symptoms’ of gene or gene-environment interactions (Guze, 1989; Pilgrim, 2002). On the other hand, it has been suggested that rather than being ‘symptoms’ disturbances in psychological processes caused by biological and social vulnerabilities and environment and life events are the final stage in a chain of events which may lead to mental health disorders (Kinderman, 2013). For example, in a large-scale eloquent study, including 32,827 participants, Kinderman et al. (2013) showed that psychological processes determined the ‘causal impact of biological, social and circumstantial risk factors on mental health’. Thus, psychological processes or ‘experiences’ (as term in our framework) far from being symptoms of gene-environment interactions may serve as the gateway to mental ill health or wellbeing This suggests that interventions at the level of ‘psychological processes’ (experiences) has great potential to reduce mental health difficulties, which in and of themselves are one of the leading causes of chronic disability (WHO, 2011) and costed an estimated $2,500 billion worldwide in 2010 (Boom, 2011).
 
In addition to psychological experiences being implicated in the causality of mental health conditions, we are beginning to understand the role that early psychological experiences may have in pathways to chronic physical ill-health. For example, Von Korff, Scott (2009) showed that >=3 childhood adversities were independently related to onset of diabetes in adulthood. The authors also showed that negative psychological experiences in childhood were associated with onset of asthma in a dose dependent way. More recently, Scott, Lim, Al-Hamzawi et al., (2015) have shown that negative psychological experiences in childhood is strongly associated with adult onset heart disease.
 
To recapitulate evidence suggests that psychological experiences can play in critical role in the causality of mental health and physical health disorders. Epidemiological studies have also shown that common mental disorders [zf1] and physical disease are strongly inter-connected, highly co-morbid and share critical pathways to ill health and disease (O’Neil et al. 2015; Druss, Walker, 2011[zf2] ). For example, in a study of 245,404 participants from 60 countries across the world, an average of between 9.3-23% of participants with one or more chronic physical condition had co-morbid depression (Moussavi et al., 2007).  This is significantly higher than depression rates in people without a chronic physical disease (p>0.0001). Moreover, even after adjustment for health conditions and socioeconomic factors, depression had the largest effect on worsening mean health scores. The authors conclude that participants with one or more chronic condition and co-morbid depression had the poorest health of all of the disease states. 
 
Cardiovascular disease, type 2 diabetes mellitus, cancer and chronic respiratory diseases are often referred to as the ‘big four’ chronic conditions, because in combination, they account for more deaths than any other. However, if one considers the global burden of chronic conditions in terms of disability rather than mortality, major depression is the second leading cause of disability (O’neil, Jacka, Quirk, Cocker and Taylor and Berk, 2015) preceded only by cardiovascular disease. In terms of disability, ‘the big four’ only account for only (54%) of all related disability adjusted life years (DALYs). Although, relative to physical health conditions, mental disorders are associated with greater disability, they are much less likely to receive treatment and this holds true across the world (Von Korff MR, Scott KM, Gureje, 2009).
 
Prevalence rates for major depression are higher for people with physical illness relative to those without. For example, 29% for people with hypotension, 22% for people with myocardial infarction, 33% for people with cancer and 27% for people with diabetes (World Health Organization, 2003).[zf3]  The World Mental Health Survey showed odds ratios across countries for the relationship between heart disease and mental health conditions were; 2:1 for depression; 2:2 for anxiety; and 1.4 for alcohol dependence. The relationship between heart disease and mental health conditions (the two biggest contributors to the global economic burden of chronic disease) appears to be reciprocal. For example, major depression has been shown to increase the risk of the development of cardiovascular disease (Gasse, Laursen, Baune, 2014). For example, strong relationships have been reported between early onset common mental health disorders and heart disease in adulthood (Gasse, Laursen, Baune, 2014). Conversely, having a physical illness is one of the strongest predictors of depression (O’Neil et al. 2015; Wilhelm K, Mitchell P, Slade T, 2003). In their meta-analysis, Roest, Martens, DeJonge, Denollet (2010) revealed anxiety disorders also increase the risk for cardio-vascular disease and cardiac related death. The relationship between mental health conditions and chronic conditions remains strong across a plethora of chronic conditions. For instance, type 2 diabetes mellitus, has been shown to increase the risk for depression (Rotella and Mannucci, 2013), anxiety (Wandell, Ljunggren, Wahlström, Carlsson, 2014) as well as schizophrenia, bipolar disorder and post-traumatic stress disorder. Meta-analyses have also shown a strong relationship between diabetes and cognitive impairment (Vancampfort D, Correll CU, Galling B, et al, 2016). Respiratory diseases and cancer have been linked with depression (Caruso R, GiuliaNanni M, Riba MB, Sabato S, Grassi, 2017). In the World Mental Health Survey, mood, anxiety, and substance dependency were shown to preceded a diagnosis of asthma (Scott, Lim, Al-Hamzawi, 2015).
 
These common mood disorders appear to share an underlying diathesis whereby mechanisms that predispose individuals to depression and anxiety for example, contribute to the development of a range of chronic physical health conditions across the life span. A greater understanding of this common underpinning diathesis is needed to better develop preventive interventions and well as treatments. Our original GENIAl model lays the foundations from which these underpinning mechanisms can be better understood (Kemp et a al. 2017). What is clear, is that interventions that fail to appreciate the role the causal role of psychological experience in physical and mental health as well as the reciprocal relationship between physical and mental health miss substantial opportunities in the prevention and the amelioration of chronic conditions. Moreover, the biases in treatment towards physical illness in the health service is inefficient given that high degree of co-morbidity with mental health conditions because we know that mental ill health affects adherence to treatments and prognosis. DiMatteo, Leeper and Croghan (2000) showed that people with depression were three times less likely to adhere to treatment regimens that people without depression. This commissioning bias also ignores the evidence that health-related quality of life is significantly lower for depressed patients than for people with physical health conditions for example, asthma, arthritis, and diabetes [Moussavi S, Chatterji S, Verdes E, Tandon A, Patel V, et al. (2007)].
 
Targeting psychological experiences may help to prevent or ameliorate the impact of chronic conditions and mental health conditions: Given the role of negative psychological experiences in creating vulnerabilities to chronic conditions and mental health disorders it follows that interventions that target psychological experience have the potential to prevent or ameliorate the impact of the mental and/or physical health conditions.
 
There is considerable evidence that psychological therapies can both improve quality of life for people with chronic conditions as well as improving health outcomes (Galway, Black, Cantwell, Cardwell, Mills, Donnelly, 2013; Happell, Davies and Scott, 2012; Hutchison, Breckon, 2011; Rehse B, Pukrop, 2003; Simpson, Booth, Lawrence, Byrne, Mair, Mercer, 2014; Stinson, Wilson, Gill, Yamada, Holt, 2009; Trautmann, Lackschewitz, Kröner-Herwig, 2006; Van Beugen S, Ferwerda M, Hoeve D, Rovers MM, Spillekom-Van Koulil S, Van Middendorp, 2014). However, Harkness, Macdonald, Valderas, Conventry, Gask and Bower, 2010)  carried out a meta-analysis which included 49 studies exploring the effectiveness of psycho-social interventions for people with type 1 and type 2 diabetes and overall found no benefit.
Cognitive Behavioural Therapy (CBT) is the most widely research psychological therapy (Butler, A. C., Chapman, J. E., Forman, E. M., & Beck, 2006). Hundreds of controlled studies have demonstrated the benefits of CBT when applied to a range of diagnostic groups including mental health disorders such as anxiety, depression, schizophrenia (Hollon, S. D., Munoz, R. F., Barlow, D. H., Beardslee, W. R., Bell, C. C., & Bernal 2002, Barlow 2002; Pilling, S., Bebbington, P., Kuipers, E., Garety, P., Geddes, J., & Orbach. 2002). CBT has also been shown to be effective for people with physical health conditions such as chronic pain, headache, cancer (Moorey, S., & Greer 2002; Holroyd, 2002, Morin, C. M., Hauri, P. J., Espie, C. A., Spielman, A. J., Buysse, D. J., & Bootzin. 1999) to name a few. A systematic review exploring internet-administered CBT for people with health problems also provided positive findings and the effects were comparable with face-to-face therapy for pain reduction and headache (Cuijpers, van Straten and Andersson, 2008).
Behaviour therapy has also been shown to be beneficial in the treamtnet of mental health problems. For example, in their meta-analysis, Cuijpers, van Straten and Wamerdam (2007a) included16 randomised studies exploring the effectiveness of behavioural activation for people with depression. They showed clear indications that the intervention was effective. A subsequent meta-analysis by the same authors \cite{Cuijpers_2007} included the findings of 13 randomized controlled studies to explore the effectiveness of problem-solving therapy for 1133 people with depression. They reported high levels of heterogeneity in the data which could not be further explained by subgroup analysis, the authors conclude that problem solving therapy has varying effects on depression but that there was no doubt that in some instances it could be effective. 
In their systematic review, Robinson, Russell and Dysch (2019) explored the effectiveness of third-wave therapies for adults with long term neurological conditions. The term ‘third wave’ refers to the third development of psychotherapy and represents an extension of CBT (Hayes, 2004). Unlike Cognitive Behavioural Therapy, third waves therapies are less concerned with modifying thoughts but rather with changing the individuals relationship to their thoughts and psychological experiences. In this study, the third wave therapies included were Compassion Focused Therapy; Acceptance and Commitment Therapy; and Mindfulness-Based Cognitive Therapy or Mindfulness-Based Stress Reduction. The findings showed that, across 19 studies, there was a significant reduction in emotional distress. The authors concluded that third waves therapies showed promise in treating transdiagnostic difficulties within neurological conditions. In this context, the authors used the term transdiagnostic to refer to the psychological processes that are common across neurological conditions, such as rumination, low mood etc. In their systematic review of three studies exploring the effectiveness of mindfulness based interventions for patients with multiple sclerosis, Simpson, Booth, Byrne and Mercer, (2014) reported significant benefits relating to quality of life, mental health and selected physical health measures. These effects were sustained at the three and six month follow up period. 
In a recent rapid systematic review, Anderson and Ozakinci (2018) explored the effectiveness of a variety of psychological interventions on quality of life, health related quality of life and/or wellbeing including only studies with ‘high scientific vigour’. This meant the inclusion of 6 randomised controlled trials with a treatment as usual control. Of the 6 studies, two were classified as short (0–3 months), two as medium- (3–12 months), and two as  long- term (12 months or more). Of the short studies, Baptist, Ross, Yany, Song, Clark (2013) carried out a six week health education-led self-regulation interventions for people with asthma and  Smeulders, Van Haastregt, Ambergen, Uszko-Lencer, Janssen- Boyce, Gorgels (2010) evaluated a six-week, nurse led, structured self-management programme for patients with chronic heart failure. This programme was also co-facilitated by a patient mentor. Of the medium duration studies, Escobar, Gara, Diaz-Martinez, Interian, Warman (2007) evaluated a 10-week, therapist led, cognitive behavioural group to patients with medically unexplained conditions. Somer, Blumenthal, Guilak, Kraus, Schmitt, Babyak (2012), reported an intervention for patients with osteoarthritis. In this study there were three treatment groups which spanned 24 weeks and was run by two clinical psychologists under the supervision of an experienced senior clinical psychologist. One group had ‘Pain Coping Skills Training’, one had ‘Behavioural Weight Management’ training and the other had both interventions. Of the long duration studies Blank, Hennessy, Eisenberg (2014) reported an intervention for patients with HIV who were offered weekly community based, nurse-led, psycho-education and symptom management sessions over a 12-month period. Also included was problem focused counselling programme for patients head or neck cancer which took place bi-monthly for 12 months. Overall, the findings indicated significant improvements to at least one component of quality of life immediately after the all of the interventions. Interestingly, one of the short duration interventions for people with asthma (Baptist et al. 2013), the medium duration interventions for people with osteoarthritis (Somer et al. 2012) and the long-term interventions for people with HIV (Blank et al. 2014) demonstrated significantly improved quality of life 12 months post intervention. This suggests that psychological interventions can have prolonged effects on the lives of people with chronic conditions (albeit in half of the studies) and that this effect is not dependent on treatment duration.