Reduced Cardiac Vagal Modulation Impacts on Cognitive Performance in CFS, 2012, Beaumont et al

[Hutan]

https://pubmed.ncbi.nlm.nih.gov/23166694/

Alison Beaumont 1, Alexander R Burton, Jim Lemon, Barbara K Bennett, Andrew Lloyd, Uté Vollmer-Conna
Free PMC article
Abstract


Background: Cognitive difficulties and autonomic dysfunction have been reported separately in patients with chronic fatigue syndrome (CFS). A role for heart rate variability (HRV) in cognitive flexibility has been demonstrated in healthy individuals, but this relationship has not as yet been examined in CFS. The objective of this study was to examine the relationship between HRV and cognitive performance in patients with CFS.

Methods: Participants were 30 patients with CFS and 40 healthy controls; the groups were matched for age, sex, education, body mass index, and hours of moderate exercise/week. Questionnaires were used to obtain relevant medical and demographic information, and assess current symptoms and functional impairment. Electrocardiograms, perceived fatigue/effort and performance data were recorded during cognitive tasks. Between-group differences in autonomic reactivity and associations with cognitive performance were analysed.

Results: Patients with CFS showed no deficits in performance accuracy, but were significantly slower than healthy controls. CFS was further characterized by low and unresponsive HRV; greater heart rate (HR) reactivity and prolonged HR-recovery after cognitive challenge. Fatigue levels, perceived effort and distress did not affect cognitive performance. HRV was consistently associated with performance indices and significantly predicted variance in cognitive outcomes.

Conclusions: These findings reveal for the first time an association between reduced cardiac vagal tone and cognitive impairment in CFS and confirm previous reports of diminished vagal activity.

 

[Sly Saint]

Participants
Thirty patients with CFS were recruited from a tertiary referral clinic associated with the University of New South Wales in Sydney, Australia, which provides a graded-activity oriented cognitive-behavioural therapy program. All patients had been diagnosed according to the international diagnostic criteria for CFS [1]. Forty control subjects were recruited by advertisement from the local community. The groups were matched for age, sex, body mass index (BMI), hours of weekly exercise, and education.

Exclusion criteria for the study were: pregnancy, primary sleep disorder, endocrine, neurological, autoimmune or cardiovascular disease, and any major depressive, psychotic or substance abuse disorder. Medications known to affect autonomic functioning including beta-blockers, benzodiazepines, corticosteroids, and any other centrally-active drugs were also exclusionary.

(1 Fukuda)
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0049518

 

[Snow Leopard]

The problem with HRV as a measure is the underlying causes are very non-specific. Reduced fitness itself can explain the difference between patients and controls and reduced fitness is a likely consequence of greater severity of the underlying illness. Mere association is not enough to derive conclusions.