Table 1.

Mental health conditions and physical co-morbidities

Co-morbid condition
Cancer	One third of people with cancer meet diagnostic criteria for at least one psychiatric disorder, including major depressive disorder, anxiety disorders, adjustment disorders, sleep disorders and delirium [24]; prevalence is higher in people with advanced cancer Comorbid mental disorders reduce quality of life, interfere with treatment adherence and, in the case of depression, may affect the rate of cancer progression [25] However, people with schizophrenia are at lower risk of having cancer (OR 0.76) [26] People with cancer who have pre-existing depression have higher all-cause, cancer-related and non-cancer related mortality [27]
Chronic obstructive pulmonary disease	Individuals with chronic obstructive pulmonary disease (COPD) are at increased risk of depressed mood and anxiety compared to the general population [28]
Cardiovascular disease	Depressed mood and cardiovascular diseases frequently occur together with an estimated 20 to 45% of individuals with heart disease and depression and those who have had a heart attack 3 times more likely to be depressed compared to the general population [29] Relationship between heart disease and depressed mood is multifactorial. Risk factors include dysfunction of the hypothalamic-pituitary-adrenal axis, increased pro-inflammatory activity, reduced omega-3 fatty acids, reduced heart rate variability, smoking, physical inactivity and low self-esteem [29] Hypertension is one of the most common co-morbid conditions in people with schizophrenia [26]. People with schizophrenia have between a 1.2–3.6-fold increased risk of coronary artery disease, and up to 3-fold increase in sudden cardiac death than the general population [11]
Diabetes	Depression is associated with a 60% increase in diabetes and diabetes with 15% increase in depression [4] People with schizophrenia have an increased risk of diabetes (OR 2.23) [26] People with diabetes who report severe symptoms of depressed mood tend to be less compliant with treatment [30], and are at higher risk of coronary heart disease [31] Chronic hypoglycaemia caused by excess insulin secretion is often associated with intense anxiety and panic attacks [32]
Arthritis	People with depression have a 34% higher prevalence of arthritis than people without depression [33]
Alzheimer’s disease	Depression is a risk factor for developing Alzheimer’s disease (AD) and dementia symptoms [34], and treatment of depression in individuals with AD can improve cognitive function and quality of life [35]