Mental health problems are amongst the most frequently encountered health problems throughout life. They have a a deep impact on patients, their families and caregivers. In Europe they are the leading cause of disability and rank third as cause of overall disease burden after cardiovascular disease and cancers. The estimated prevalence of mental disorders in the WHO European Region in 2015 was 110 million, 12% of population . In 2015, 4.1% of all deaths in the 28 countries of the European Union, 9.0% in the United Kingdom, were due to mental and behavioural disorders .
There is a close interdependence of physical and mental health. Patients with serious mental illness die 17 years earlier and poor mental health has been identified as a risk factor to develop medical problems including cardiovascular disease . Poor mental health is associated with risk-prone behaviours, such as smoking, drug and alcohol use, risky sexual behaviour  and poor adherence to taking prescribed medicines .
Medical conditions are directly linked to the development of mental health problems. For example, patients with Chronic Obstructive Pulmonary Disease (COPD), cardiovascular diseases or diabetes mellitus are three times more likely to develop psychiatric comorbidity . Patients with epilepsy have a 30-35% lifetime prevalence of depression  and up to 48% of patients with rheumatoid arthritis suffer from depressive symptoms .
Mental health has a significant impact on spending in healthcare as it interacts with and worsens physical illnesses. For example, in England 12-18% of expenditure on long-term medical conditions, £8-£13 billion, has been linked to poor mental health. Per patient, this is an increase from an average of £3,910 to £5,670 a year for each person on spending for chronic medical conditions, a 45% increment . Addressing mental health as part of chronic disease management has been shown to have a positive effect on health outcomes and health expenditure [10–12].
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1 WHO Regional Office for Europe. Fact Sheet: Mental Health. 2016.http://www.euro.who.int/en/health-topics/noncommunicable-diseases/mental-health/data-and-resources/fact-sheet-mental-health-2019 (accessed 1 Aug 2019).
2 eurostat. Mental health and related issues statistics - Statistics Explained. 2018.https://ec.europa.eu/eurostat/statistics-explained/index.php/Mental_health_and_related_issues_statistics#Deaths_from_mental_and_behavioural_disorders.2C_Alzheimer.E2.80.99s_disease_and_intentional_self-harm (accessed 1 Aug 2019).
3 Chang C-K, Perera G, Stewart R, et al. Life Expectancy at Birth for People with Serious Mental Illness and Other Major Disorders from a Secondary Mental Health Care Case Register in London. PLoS One 2011;6:e19590. doi:10.1371/journal.pone.0019590
4 World Health Organization. Risks to Mental Health: An Overview of Vulnerabilities and Risk Factors, Background paper by WHO secretariat for the development of a comprehensive mental health action plan. Geneva: 2012.
5 DiMatteo MR, Lepper HS, Croghan TW. Depression Is a Risk Factor for Noncompliance With Medical Treatment. Arch Intern Med 2003;160:2101. doi:10.1001/archinte.160.14.2101
6 Guthrie E, Palmer L, Lelliot P, et al. No Health without Mental Health The Supporting Evidence. 2010.
7 Kanner AM, Schachter SC, Barry JJ, et al. Depression and epilepsy: Epidemiologic and neurobiologic perspectives that may explain their high comorbid occurrence. Epilepsy Behav. 2012;24:156–68. doi:10.1016/j.yebeh.2012.01.007
8 Matcham F, Rayner L, Steer S, et al. The prevalence of depression in rheumatoid arthritis: a systematic review and meta-analysis. Rheumatology (Oxford) 2013;52:2136–48. doi:10.1093/rheumatology/ket169
9 Naylor C, Parsonage M, McDaid D, et al. Long-term conditions and mental health: The cost of co-morbidities. 2012;:1–32.
10 Abell F, Potter C, S P, et al. The Effect of Including a Clinical Psychologist in Pulmonary Rehabilitation on Completion Rates and Hospital Resource Utilisation in Chronic Pulmonary Disease. Thorax 2008;63:A93. doi:10.1136/sextrans-2013-051184.1214
11 Kilbourne AM, Post EP, Nossek A, et al. Improving Medical and Psychiatric Outcomes Among Individuals With Bipolar Disorder: A Randomized Controlled Trial. Psychiatr Serv 2008;59:760–8. doi:10.1176/ps.2008.59.7.760
12 Spurgeon P, Hicks C, Barwell F, et al. Counselling in primary care: A study of the psychological impact and cost benefits for four chronic conditions. Eur J Psychother Couns 2005;7:269–90. doi:10.1080/13642530500367753