Depression

Depression or low mood and the more severe major depressive disorder (clinical depression) are common but potentially serious mood disorders. Depression causes severe symptoms that affect how someone feels, thinks, and handles daily activities, such as sleeping, eating, or working. To be diagnosed with depression, the symptoms must be present for at least two weeks.

Depression as expressed in patients with ME/CFS is generally considered as secondary depression or reactive depression due to the debilitating effects of ME/CFS. Secondary or reactive depression is common in many chronic illnesses as well as cancer, which may be an acute or chronic illness.

Misdiagnosis of ME/CFS
ME/CFS is often misdiagnosed as depression, as many symptoms can overlap. Older case definitions, such as the Fukuda criteria and the Holmes criteria do not differentiate enough between the symptomatic criteria of depression and chronic fatigue syndrome (CFS).

Differences
In 2006, Hawk, Jason, and Torres-Harding found that symptom occurrence variables as identified in the Fukuda criteria only correctly classified 84.4% of cases when comparing patients with major depressive disorder and ME/CFS.

Hawk, Jason, and Torres-Harding defined several symptoms in which ME/CFS patients experience differently than major depressive disorder patients: Using this symptom list, Hawk, [[Leonard Jason, and Torres-Harding were able to report 100% correct classification between patients with depressive disorder versus ME/CFS.
 * percentage of time fatigue was reported
 * post-exertional malaise (PEM) severity
 * unrefreshing sleep severity
 * confusion–disorientation severity
 * shortness of breath severity
 * and fewer self-reproach items (as scored on the Beck's Depression Inventory)

LaFerney, a psychiatric clinical nurse specialist, outlined several differences between depression in major depressive disorder and ME/CFS:
 * Individuals with major depressive disorder often cannot provide a reason or identify a loss to explain their depressed mood. ME/CFS patients are more likely to report feeling discouraged and depressed because of the inability to perform tasks, be employed, or engage in social functions due to ME/CFS symptoms.
 * Depressed patients typically report a lack of interest in activities they previously found pleasurable. ME/CFS patients say they would engage in favorite activities more if their illness would allow it.
 * One question that can differentiate the two groups is to ask the patient, "If you were cured tomorrow, what would you do?" Depressed patients typically can not answer the question without forethought. ME/CFS patients typically can list an abundance of activities without prompt. The Forgotten Plague Facebook page had a "If I was cured tomorrow..." campaign encouraging ME/CFS patients to upload their dreams to highlight this difference.
 * Although both groups of patients report fatigue, only ME/CFS report post-exertional malaise: with symptoms typically worsening 12 to 48 hours after an activity and lasting for days to weeks.
 * In depressed patients, the diminished ability to think or concentrate should improve with antidepressant drugs or therapies. In patients with ME/CFS, antidepressants often do not improve concentration or memory.

Dr. Sarah Myhill identified an additional difference between depression and CFS:
 * Exercise makes CFS patients much worse, but can be positively therapeutic in pure depression

Prevalence

 * Katrina Berne reports a prevalence of 65-90% for depression.

Symptom recognition

 * In the 1988 Holmes criteria, depression is an optional criteria for diagnosis, under the section Minor Symptom Criteria - Neuropsychologic Complaints. It is not a diagnosable symptom in the current CDC criteria, the Fukuda criteria, the Canadian Consensus Criteria or the International Consensus Criteria although secondary depression is recognized as a possible symptom and comorbidity of ME/CFS in the International Consensus Criteria.

Notable studies

 * 2006, Differential diagnosis of chronic fatigue syndrome and major depressive disorder (Full Text)
 * 2008, A Systematic Review of Chronic Fatigue Syndrome: Don't Assume It's Depression (Full Text)

Possible causes
Depression in ME/CFS patients may be caused by:
 * The impact of living with a poorly understood chronic illness, known as reactive depression or secondary depression
 * Someone with ME/CFS may have depression unrelated to their ME/CFS symptoms, known as primary depression
 * People with ME/CFS typical lose the natural benefit of exercise, which means a person who previously used exercise to improve their mood is no longer able to do this
 * Depression is a potential side effect of some drugs, particularly a class of drugs known as mood stabilizers, which are used for bipolar depression (manic depression) but cause depression or worsen depression in people without bipolar disorder.

Potential treatments

 * Antidepressants
 * Cognitive behavioral therapy for depression (CBT)
 * Mindfulness and Meditation

Learn more

 * 2008, A Systematic Review of Chronic Fatigue Syndrome: Don’t Assume It’s Depression
 * 2008, Depression or chronic fatigue syndrome? by Michael C. Laferney
 * 2014, How to Prove to Your Doctor You’ve Got Chronic Fatigue Syndrome (ME/CFS) And Are Not Just Depressed by Cort Johnson