E2 ModeratePreliminaryPEM not requiredCross-SectionalPeer-reviewedReviewed
Standard · 3 min
Psychological states and neuropsychological performances in chronic Lyme disease.
Elkins, L E, Pollina, D A, Scheffer, S R et al. · Applied neuropsychology · 1999 · DOI
Quick Summary
This study looked at mood and thinking abilities in 30 people with post-Lyme syndrome (a condition that can develop after Lyme disease). Researchers found that these patients had lower levels of positive feelings (like happiness or hopefulness) compared to the general population, but their actual thinking and memory skills tested normally. The study suggests that reduced positive mood, rather than depression or other psychiatric conditions, may be the most important psychological marker of this illness.
Why It Matters
This study is relevant to ME/CFS because it identifies a specific mood pattern (low positive affect without typical depression) that may characterize post-infectious conditions, offering a potential marker for clinical assessment. Understanding the relationship between mood states and cognitive complaints helps clinicians and patients better distinguish primary psychiatric symptoms from those related to organic illness.
Observed Findings
Post-Lyme syndrome participants showed reduced positive affect but normal negative affect levels, a pattern distinct from depression.
Neuropsychological test performances fell within normal ranges for all cognitive measures tested.
Positive affect levels correlated significantly with total symptom severity and severity of cognitive complaints.
Positive affect was not associated with illness duration, initial neurological manifestations, or treatment history.
Psychiatric disorder incidence was not elevated in the PLS group compared to general population rates.
Inferred Conclusions
Low positive affect is the most useful psychological marker for understanding symptom burden in post-Lyme syndrome.
The affect pattern in PLS is distinct from clinical depression and similar to patterns observed in chronic fatigue syndrome.
Objective cognitive dysfunction does not appear to underlie cognitive complaints in this PLS population, suggesting complaints may be mood-related or effort-dependent.
Psychiatric history and current psychiatric status are not reliable predictors of neuropsychological performance in PLS.
Remaining Questions
Does the low positive affect pattern identified in PLS occur in ME/CFS patients, and if so, does it have similar prognostic implications?
What This Study Does Not Prove
This study does not prove that low positive affect causes cognitive symptoms or symptom severity—it only shows an association. The cross-sectional design prevents determination of causality or temporal relationships. The study also does not establish whether these findings apply to ME/CFS patients, as it examined a Lyme disease population, and results may not generalize beyond this specific post-infectious context.
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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