E2 ModerateModerate confidencePEM not requiredLongitudinalPeer-reviewedReviewed
Neuropsychological functioning, illness perception, mood and quality of life in chronic fatigue syndrome, autoimmune thyroid disease and healthy participants.
Dickson, A, Toft, A, O'Carroll, R E · Psychological medicine · 2009 · DOI
Quick Summary
This study compared thinking and memory skills, mood, and quality of life in people with ME/CFS, people with thyroid disease, and healthy people. People with ME/CFS showed more problems with memory, attention, and concentration, plus higher levels of anxiety and depression. Importantly, the attention problems stayed even after researchers accounted for mood issues, suggesting cognitive problems are a core feature of ME/CFS rather than just a result of feeling depressed or anxious.
Why It Matters
This research helps establish that cognitive difficulties in ME/CFS—particularly problems with attention and memory—are a genuine biological feature of the illness, not simply caused by depression or anxiety. This distinction is important for validating patient experiences and guiding clinical assessment and treatment approaches.
Observed Findings
- CFS patients showed significantly greater impairment on immediate and delayed memory tests compared to both AITD and healthy controls
- CFS patients demonstrated significantly greater attention and visuo-constructional ability deficits
- CFS patients reported significantly higher anxiety and depression levels than comparison groups
- Attention impairment in CFS remained statistically significant even after controlling for mood effects
- CFS patients reported significantly lower quality of life and greater illness concerns than AITD patients, with less perceived treatment control
Inferred Conclusions
- Attention deficit is the primary cognitive impairment in ME/CFS and represents a core feature of the illness independent of psychiatric comorbidity
- Lower treatment control beliefs and greater illness concerns in CFS patients may be causally related to affective symptoms rather than vice versa
- Cognitive impairment in CFS cannot be explained as secondary to depression or anxiety alone
Remaining Questions
- What is the underlying biological mechanism causing attention and memory deficits in ME/CFS?
- Do cognitive impairments fluctuate with disease exacerbations (post-exertional malaise) or remain stable over longer time periods?
What This Study Does Not Prove
This study does not prove what causes the cognitive impairment in ME/CFS or whether it is reversible. The 5-week observation period is too short to determine long-term trajectories or whether cognitive function changes with disease progression or treatment. Correlation between illness perception and mood does not establish which is the cause and which is the effect.
Tags
Symptom:Cognitive DysfunctionFatigue
Method Flag:PEM Not DefinedWeak Case DefinitionSmall SampleExploratory Only
Metadata
- DOI
- 10.1017/S0033291708004960
- PMID
- 19144216
- 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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