Abstract
BackgroundPrimary aim of this study was to compare cognitive performance of patients with chronic Q fever or Q fever fatigue syndrome (QFS) to matched controls from the general population, while taking performance validity into account. Second, we investigated whether objective cognitive performance was related to subjective cognitive complaints or psychological wellbeing.MethodsCognitive functioning was assessed with a neuropsychological test battery measuring the domains of processing speed, episodic memory, working memory and executive functioning. Tests for performance validity and premorbid intelligence were also included. Validated questionnaires were administered to assess self-reported fatigue, depressive symptoms and cognitive complaints.ResultsIn total, 30 patients with chronic Q fever, 32 with QFS and 35 controls were included. A high percentage of chronic Q fever patients showed poor performance validity (38%) compared to controls (14%, p = 0.066). After exclusion of participants showing poor performance validity, no significant differences between patients and controls were found in the cognitive domains. QFS patients reported a high level of cognitive complaints compared to controls (41.2 vs 30.4, p = 0.023). Cognitive complaints were not significantly related to cognitive performance in any of the domains for this patient group.ConclusionsThe high level of self-reported cognitive complaints in QFS patients does not indicate cognitive impairment. A large proportion of the chronic Q fever patients showed suboptimal mental effort during neuropsychological assessment. More research into the underlying explanations is needed. Our findings stress the importance of assessing cognitive functioning by neuropsychological examination including performance validity, rather than only measuring subjective cognitive complaints.
Highlights
Primary aim of this study was to compare cognitive performance of patients with chronic Q fever or Q fever fatigue syndrome (QFS) to matched controls from the general population, while taking performance validity into account
Participants Chronic Q fever patients were recruited through physicians from hospitals that were located in the region with the highest number of acute Q fever infections during the epidemic
Characteristics and self-reported symptoms of study populations In total, 30 chronic Q fever patients, 32 QFS patients and 35 controls were recruited, of which 23 matched the chronic Q fever group and 21 matched the QFS group (9 controls were included in both matched control groups, 14 of the 23 and 12 of the 21 matched controls were unique)
Summary
Primary aim of this study was to compare cognitive performance of patients with chronic Q fever or Q fever fatigue syndrome (QFS) to matched controls from the general population, while taking performance validity into account. The other 40% of infected individuals develop symptoms, ranging from a mild flu-like and usually self-limiting disease to more serious conditions such as pericarditis or myocarditis [2]. 1–5% of Q fever patients develop a chronic infection, commonly manifested as endocarditis or vascular infection, called chronic Q fever [1]. Chronic Q fever occurs primarily in patients with pre-existing cardiac valvulopathies, vascular abnormalities, or immunosuppression [2]. Another long-term manifestation of Q fever is called Q fever fatigue syndrome (QFS) [3], which consists of severe debilitating fatigue lasting for more than 6 months, experienced by patients months or years after the acute Q fever infection [4, 5]
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