It is estimated that depression is extremely prevalent with comorbid medical conditions and may be more common with hospitalised and elderly patients. It presents a complex challenge to physicians, and if left untreated, may lead to the exacerbation of the underlying medical condition. 

Evidence suggests that there is an increase of approximately 50% in the medical costs of chronic medical illness with comorbid depression, even after controlling for severity of physical illness. 

Depression is clearly linked with increased morbidity and mortality in medical conditions such as diabetes, stroke and heart disease. It may also lead to increased disability in patients with chronic disease and their utilisation of medical care.

Depression also affects a patient’s ability to comply with the medication regimes, dietary restrictions, or lifestyle modifications that are an integral component of the successful management of many chronic diseases. 

Older adults with depression are more prone to be noncompliant with their prescribed medications leading to rapid deterioration in their mental and physical status.

Patients with comorbid anxiety and depressive disorder present with significantly more medically unexplained symptoms than those with chronic medical illness alone. 

It is also known to heighten somatisation of the chronic medical illnesses such as head injury, inflammatory bowel disease, hepatitis C, diabetes mellitus and chronic tinnitus with hearing impairment.

Prevalence of depression varies according to the medical condition and a brief outline is given below to understand its effect in various illnesses.

Cardiovascular disorders

Depression is extremely prevalent in patients with cardiovascular disease, and it is linked to poor clinical outcomes (increased mortality and morbidity). It is considered as a poor prognostic factor when it develops following an acute myocardial infarction. 

Available studies report 65% of patients developing depression following acute myocardial infarction, with 15-22% meeting the criteria of major depressive disorder. 

Major depression is also reported as a serious mortality risk factor approximating other factors, such as left ventricular dysfunction and previous myocardial infarction. It also affects cardiac patients’ ability to comply with overall treatment, follow-up with cardiac rehabilitation and make long-term lifestyle changes.

Neurological disorders

The prevalence of major depression has been found to be 20-30% in patients with Parkinson’s disease.

One study report symptoms of anxiety and depression in 40% of patients with this disorder. Risk factors for psychological distress in Parkinson’s disease include hallucinations, cognitive impairment, stage of illness and functional disability.

Depressive disorders are the most common type of psychiatric comorbidity in epilepsy. Patients with seizure disorders have a much higher incidence of major depressive disorders and suicide as compared to normal controls. 

Among epileptic patients, partial complex seizure disorders of temporal- and frontal-lobe origin and patients with poorly controlled seizures are considered a high-risk group. 

Major depression also poses a significant challenge in cerebrovascular accidents and noted to be more common in the first few months. 

Factors associated with depression in patients with stroke are cognitive impairment, social isolation, residual symptoms like dysphasia, incontinence, hemiparesis and low quality of life.

Diabetes

Patients with diabetes are two to three times more likely to experience depression as those without the illness. It is also associated with more diabetes-related medical complications, higher risk of heart disease, stroke and increased utilisation of healthcare services. 

Severity of depression also correlates positively with both the degree of hyperglycaemia and the presence of diabetic neuropathy. 

Obesity 

While the relationship between depression and severe obesity is unclear, several studies have shown that severely obese patients are at high risk for depression. 

In one particular study, more than 2,000 adults with major depression were followed for five years. Participants with body mass index (BMI) > 30 at the baseline were associated with an increased risk of depression even after controlling for covariates such as gender, marital status, education, social support, physical health problems, and functional limitations.

Arthritis 

More than 50% of patients with rheumatoid arthritis experience depressive symptoms. These patients have higher pain scores and are more difficult to manage than non-depressed patients. Anti-inflammatory agents, muscle relaxants, and opiates may also cause depressive symptoms and careful evaluation is needed to clarify the diagnosis.

Terminal illness

Depression is often difficult to diagnose in patients with terminal conditions because of the complexity and constraints of palliative care, patient and family reluctance to acknowledge distress, and the presence of multiple symptoms. 

Prevalence of depression in terminal cancer ranges up to 40%. In women with early breast cancer, the prevalence of depression, anxiety, or both in the year after diagnosis is nearly double when compared to the general female population. When severe depression precedes cancer, the depressive illness may present as an additional risk factor. 

Some patients with advanced cancer express the wish for an early death, whether natural or by suicide, which may be associated with depression.

Management

Managing depression in patients with chronic medical illness is a complex task that requires specialist expertise. Treatment has been shown to improve the general wellbeing of the patients and may also be associated with cost savings. 

A prescribed regime should address physical symptoms along with emotional symptoms to achieve full remission and a return to pre-morbid level of functioning. 

The National Institute for Health and Clinical Excellence (NICE) recommends the use of collaborative care models for these cases. This involves structured, pro-active management by multidisciplinary teams and enhanced interprofessional communication and using evidence-based approaches. 

Cognitive behavioural therapy is considered a first-line treatment in mild depressive episodes along with addressing symptoms of the underlying physical condition. Antidepressant drugs remain the most specific and readily available treatment of major depressive disorders in the setting of medical disease.

Treatment outcome studies involving drug treatment or short-term psychotherapeutic approaches, or both, are needed to develop consensus guidelines in this field and to ensure standardised approaches towards patient care.

Source material

1. Katon W, Sullivan MD. Depression and chronic medical illness. J Clin Psychiatry 1990; 51s
2. Lebowitz BD, Pearson JL, Schneider LS et al. Diagnosis and treatment of depression in late life. (Consensus statement update). JAMA 1997; 278: 1186-1190
3. Carney RM, Freedland KE, Miller GE, Jaffe AS. Depression as a risk factor for cardiac mortality and morbidity. A review of potential mechanisms. J Psychosomatic Res 2002; 53: 897-902
4. Hlatky MA, Haney T, Barefoot JC et al. Medical, psychological, and social correlates of work disability among men with coronary artery disease. Am J Cardiol 1986
5. Carney RM, Freedland KE, Eisen SA et al. Major depression and medication adherence in elderly patients with coronary artery disease. Health Psychol 1995; 14(1): 88-90
6. Frasure-Smith N, Lesperance F, Talajic M. Depression following myocardial infarction. Impact on 6-month survival. JAMA 1993; 270: 1819-1825
7. Depression, introversion and mortality following stroke. Aust NZ J Psychiatry 1993; 27: 443-449
8. Kanner A, Balabanov A. Depression and epilepsy: how closely related are they? Neurol 2002; 58(8 Suppl 5): S27-S39
9. Wiegartz P, Seidenberg M, Woodard A et al. Co-morbid psychiatric disorder in chronic epilepsy: recognition and etiology of depression. Neurol 1999; 53(5 Suppl 2): S3-S8
10. Wiegartz P, Seidenberg M, Woodard A et al. Co-morbid psychiatric disorder in chronic epilepsy: recognition and etiology of depression. Neurol 1999; 53(5 Suppl 2): S3-S8
11. Carney C. Diabetes mellitus and major depressive disorder: an overview of prevalence, complications, and treatment. Depress Anxiety 1998; 7(4): 149-157
12. National Institute of Mental Health. The strategic plan for mood disorders research. Washington, DC: NIMH, 2002
13. Goodnick PJ, Henry J, Buki V. Treatment of depression in patients with diabetes mellitus. J Clin Psychiatry 1995; 56(4): 128-136
14. Grundy SM, Benjamin IJ, Burke GL et al. Diabetes and cardiovascular disease: a statement for healthcare professionals from the American Heart Association.1999; 1134-1146
15. Roberts RE, Deleger S, Strawbridge WJ, Kaplan GA. Prospective association between obesity and depression: evidence from the Alameda County Study. Int J Obes 2003; 27: 514-552
16. Hagglund KJ, Haley WE, Reveille JD, Alarcon GS. Predicting individual differences in pain and functional impairment among patients with rheumatoid arthritis. Arthritis Rheum 1989; 32(7): 851-858
17. Simon G, Katon W, Lin E et al. Cost-effectiveness of systematic depression treatment among people with diabetes mellitus. Arch Gen Psychiatry 2007; 64: 65-72
18. Katon W, Unutzer J, Fan MY et al. Cost-effectiveness and net benefit of enhanced treatment of depression for older adults with diabetes and depression. Diabetes Care 2006; 29: 265-270
19. National Institute for Health and Clinical Excellence. Depression in adults with a chronic physical health problem: treatment and management (National Clinical Practice Guideline No 91). NICE, 2009
20. Fava GA, Sonino N, Wise TN. Management of depression in medical conditions. Psychother Psychosom 1988; 49: 81-102