E2 ModerateModerate confidencePEM not requiredCross-SectionalPeer-reviewedReviewed
"Functional" or "psychosomatic" symptoms, e.g. a flu-like malaise, aches and pain and fatigue, are major features of major and in particular of melancholic depression.
Maes, Michael · Neuro endocrinology letters · 2009
Quick Summary
This study looked at whether depression and ME/CFS share similar physical symptoms like fatigue, muscle pain, and feeling like you have an infection. Researchers found that people with severe depression often experience these "body-centered" symptoms as a major part of their illness. The findings suggest that doctors should pay more attention to these physical symptoms when diagnosing and treating depression.
Why It Matters
This research is significant because it documents substantial overlap between depression symptomatology and ME/CFS-like symptoms, supporting the biological plausibility of comorbidity and suggesting that ME/CFS patients with depression may have overlapping pathophysiological mechanisms. Understanding these shared symptom profiles may improve diagnostic accuracy and guide treatment approaches for patients experiencing both conditions.
Observed Findings
- Two symptom clusters were identified in depressed patients: a fatigue and somatic cluster (including fatigue, aches, pain, muscular tension, concentration difficulties, memory problems, and subjective infection feelings) and a depression cluster (sadness, sleep disorders, autonomic symptoms).
- Subjective experience of infection, aches and pain, muscular tension, fatigue, concentration difficulties, and failing memory were the most significant differentiators between symptom severity clusters.
- Strong associations were found between fatigue/somatic symptoms and melancholic depression and chronic depression subtypes.
- Treatment-resistant depression was characterized by higher depression factor scores.
- Fatigue, subjective infection experience, and sadness on the Hamilton Depression Rating Scale showed strong correlations with Fibromyalgia and Chronic Fatigue Syndrome Scale items.
Inferred Conclusions
- Fatigue and somatic symptoms represent a major diagnostic feature of depression, particularly in melancholic and chronic presentations, and should be incorporated into depression diagnostic criteria and severity rating scales.
- The severity of fatigue and somatic symptoms quantitatively predicts depression severity, chronicity, and treatment resistance rather than representing a distinct qualitative symptom profile.
- Biological overlap between depression and ME/CFS-like symptoms suggests shared or related pathophysiological mechanisms worthy of further investigation.
What This Study Does Not Prove
This study does not prove that depression causes ME/CFS or vice versa—it only shows symptom overlap in depressed patients. The cross-sectional design cannot establish temporal relationships or causality. Additionally, the study examined depression patients rather than ME/CFS patients directly, so findings may not fully characterize ME/CFS itself or explain the relationship from the ME/CFS perspective.
Tags
Symptom:Cognitive DysfunctionPainFatigueUnrefreshing Sleep
Method Flag:PEM Not DefinedWeak Case DefinitionNo ControlsExploratory OnlySmall Sample
Metadata
- PMID
- 20035251
- Review status
- Editor reviewed
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 12 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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