Cognitive Impairments in Two Samples of Individuals with ME/CFS and Long COVID: A Comparative Analysis.
Sirotiak, Zoe, Adamowicz, Jenna L, Thomas, Emily B K · Journal of clinical psychology in medical settings · 2025 · DOI
Quick Summary
This study looked at brain fog and concentration problems in people with ME/CFS and long COVID using data from over 27,000 Americans. Researchers found that people with ME/CFS are about 6 times more likely to experience cognitive difficulties like memory and concentration problems compared to people without these conditions, while long COVID increases the risk about 2 times. People who have both ME/CFS and long COVID together face even greater cognitive challenges.
Why It Matters
Understanding how cognitive impairment differs between ME/CFS and long COVID is critical for accurate diagnosis, appropriate clinical management, and targeted research. This study provides epidemiological evidence that ME/CFS carries a particularly high cognitive burden, which can guide healthcare providers in assessing and supporting patients and inform research prioritizing cognitive dysfunction mechanisms.
Observed Findings
ME/CFS was associated with a 5-6 fold increased likelihood of reported cognitive difficulties across both survey years.
Long COVID was associated with a 2-fold increased likelihood of cognitive difficulties.
Individuals with both ME/CFS and long COVID showed the highest rates of cognitive impairment.
Cognitive difficulties remained significantly associated with ME/CFS even after controlling for long COVID and demographic factors.
Results were consistent across two separate cohorts (2022 and 2023 data).
Inferred Conclusions
ME/CFS carries a substantially greater risk of cognitive impairment than long COVID alone.
Cognitive difficulties represent a significant and measurable feature distinguishing ME/CFS and long COVID from the general population.
Comorbid ME/CFS and long COVID may have additive or synergistic effects on cognitive function.
Cognitive impairment should be considered a core symptom domain in ME/CFS clinical assessment and management.
Remaining Questions
What specific cognitive domains (memory, processing speed, executive function, attention) are most affected in ME/CFS versus long COVID?
What This Study Does Not Prove
This study cannot establish causation—it only shows associations between these conditions and cognitive difficulties. It relies on patients' self-reported cognitive problems rather than objective testing, so the actual severity and specific types of cognitive impairment cannot be precisely measured. The study also cannot identify what biological mechanisms or disease features cause these cognitive difficulties.
What biological mechanisms underlie the cognitive impairment—post-viral neuroinflammation, mitochondrial dysfunction, vascular changes, or other factors?
How do cognitive difficulties change over time and are there periods of improvement or deterioration in ME/CFS and long COVID?
Do specific ME/CFS symptom profiles or severity levels predict greater cognitive impairment, and can objective neuropsychological testing better characterize these deficits?