This study examined whether post-infective fatigue syndrome (PIFS) is associated with a disturbance in bidirectional autonomic signaling resulting in heightened perception of symptoms and sensations from the body in conjunction with autonomic hyper-reactivity to perceived challenges. [Note: Previous studies by the Dubbo Infection Outcomes Study Group, including Drs. Vollmer-Conna and Lloyd, reported on patients with “post-infective fatigue syndrome consistent with CFS.”]
We studied 23 patients with PIFS and 25 healthy matched control subjects. A heartbeat discrimination task and a pressure pain threshold test were used to assess interoceptive sensitivity. [Sensitivity to signals from inside the body – especially the gut & other internal organs.] Cardiac response was assessed over a 4-min Stroop task. [Timed Stroop tasks test cognitive agility and thus exert some stress; for example how quickly the subject can select color words printed in contradictory colors, such as the word "green" colored red.]
PIFS was associated with higher accuracy in heartbeat discrimination and a lower pressure pain threshold.
Increased interoceptive sensitivity:
• Correlated strongly with current symptoms
• And potentiated differences in the cardiac response to the Stroop task, which in PIFS was characterized by insensitivity to task difficulty and lack of habituation.
Our results provide the first evidence of heightened interoceptive sensitivity in PIFS. Together with the distinct pattern in cardiac responsivity these findings present a picture of physiological hyper-vigilance and response inflexibility.
Source: Biological Psychology, Sep 2010;85(1):97-103. PMID: 20678991, Kadota Y, Cooper G, Burton AR, Lemon J, Schall U, Lloyd A, Vollmer-Conna U. School of Psychiatry, University of NSW, Sydney; Schizophrenia Research Institute, Sydney; Priority Centre for Brain & Mental Health Research, University of Newcastle, Newcastle; Hunter Medical Research Institute, Newcastle; Centre for Infection and Inflammation Research, School of Medical Sciences, University of NSW, Sydney, Australia. [Email: firstname.lastname@example.org]