Co-Occurrence of Depression with Medical, Psychiatric, And Substance Abuse Disorders
Clinical depression is a common and serious medical illness that can be effectively treated. The risk of clinical depression is often higher in individuals with serious medical illnesses, such as heart disease, stroke, cancer and diabetes. However, the warning signs are frequently discounted by patients and family members, who mistakenly assume feeling depressed is normal for people struggling with serious health conditions. In addition, the symptoms of depression are frequently masked by these other medical illnesses, resulting in treatment that addresses the symptoms but not the underlying depression. It is a myth that depression is a “normal” emotional response to another illness; it’s extremely important to simultaneously treat both medical illnesses.
Impact of Depression in Primary Care Settings
- Nearly 74 percent of Americans who seek help for depression or symptoms of depression will go to a primary care physician rather than a mental health professional.
- The rate of depression among those with medical illnesses in primary care settings is estimated at five to 10 percent. Among those hospitalized, the rate is estimated at 10 to 14 percent.
- The more severe the medical condition, the more likely that patient will experience clinical depression. 
- People with depression experience greater distress, an increase in impaired functioning and less ability to follow medical regimens, thus hindering the treatment of any other medical conditions.
- Unfortunately, the diagnosis of depression is missed 50 percent of the time in primary care settings.
Why Depression and Medical Illnesses Often Occur Together
- Medical disorders may contribute biologically to depression.
- Medically ill people may become clinically depressed as a psychological reaction to the prognosis, the pain and/or incapacity caused by the illness or its treatment. 
- Though occurring together, depression and a general medical disorder may be unrelated.
Prevalence of Depression Co-occurring With Other Medical Illnesses
Heart Disease and Depression
- Depression occurs in 40 to 65 percent of patients who have experienced a heart attack, and in 18 to 20 percent of people who have coronary heart disease, but who have not had a heart attack.
- After a heart attack, patients with clinical depression have a three to four times greater chance of death within the next six months.4
- Men and women with depression are at increased risk for coronary artery disease but only men are at greater risk for dying.
Stroke and Depression
- Depression occurs in 10 to 27 percent of stroke survivors and usually lasts about one year.
- An additional 15-40 percent of stroke survivors experience some symptoms of depression within two months after the stroke.6
- Individuals reporting five or more depressive symptoms have more than a 50 percent risk of mortality due to stroke in the subsequent 29 years.
Cancer and Depression
- One in four people with cancer also suffer from clinical depression. 
- Depression is sometimes mistaken as a side effect of corticosteroids or chemotherapy, both treatments for cancer.8
- Depressive symptoms can be mistakenly attributed to the cancer itself, which can also cause appetite and weight loss, insomnia and loss of energy.
Diabetes and Depression
- People with adult onset diabetes have a 25 percent chance of having depression.
- Depression also affects as many as 70 percent of patients with diabetic complications.
Eating Disorders and Depression
- Research shows a strong relationship between depression and eating disorders (anorexia and bulimia nervosa) in women.
Alcohol/Drugs and Depression
- Research shows that one in three depressed people also suffer from some form of substance abuse or dependence.
Common Symptoms of Depression and Other Medical Disorders
- Weight loss, sleep disturbances, and low energy may occur in people with diabetes, thyroid disorders, some neurological disorders, heart disease, cancer and stroke –and also are common symptoms of depression.
- Apathy, poor concentration and memory loss can occur in individuals with Parkinson’s disease and Alzheimer’s disease – and also are common symptoms of depression.
- Medications for high blood pressure, Parkinson’s disease, and other medical problems can produce side effects similar to the symptoms of depression.
Importance of Treatment
- People who get treatment for co-occurring depression often experience an improvement in their overall medical condition, better compliance with general medical care and a better quality of life.
- More than 80 percent of people with depression can be treated successfully with medication, psychotherapy or a combination of both.
- Early diagnosis and treatment can reduce patient discomfort and morbidity, and can also reduce the costs associated with misdiagnosis, and the risks and costs associated with suicide.
 National Institute of Mental Health, “Co-occurrence of Depression with Medical, Psychiatric and Substance Abuse Disorders,” Accessed July 1999. Netscape: http://www.nimh.nih.gov/depression/co_occur/abuse.htm.