Plasma neuropeptide Y: a biomarker for symptom severity in chronic
Chronic fatigue syndrome (CFS) is a complex, multi-symptom illness
with a multisystem pathogenesis involving alterations in the nervous,
endocrine and immune systems. Abnormalities in stress responses have
been identified as potential triggers or mediators of CFS symptoms.
This study focused on the stress mediator neuropeptide Y (NPY). We
hypothesized that NPY would be a useful biomarker for CFS.
Methods: The CFS patients (n = 93) were from the Chronic Fatigue and
Related Disorders Clinic at the University of Miami and met the 1994
case definition of Fukuda and colleagues.
Healthy sedentary controls (n = 100)) were from NIH or VA funded
studies. Another fatiguing, multi-symptom illness, Gulf War Illness
(GWI), was also compared to CFS.
We measured NPY in plasma using a radioimmunoassay (RIA). Psychometric
measures, available for a subset of CFS patients included: Perceived
Stress Scale, Profile of Mood States, ATQ Positive &Negative Self-Talk
Scores, the COPE, the Beck Depression Inventory, Fatigue Symptom
Inventory, Cognitive Capacity Screening Examination, Medical Outcomes
Survey Short Form-36, and the Quality of Life Scale.
Results: Plasma NPY was elevated in CFS subjects, compared to controls
(p=.000) and to GWI cases (p=.000).
Receiver operating characteristics (ROC) curve analyses indicated that
the predictive ability of plasma NPY to distinguish CFS patients from
healthy controls and from GWI was significantly better than chance
alone. In 42 patients with CFS, plasma NPY had significant
correlations (<0.05) with perceived stress, depression,
anger/hostility, confusion, negative thoughts, positive thoughts,
general health, and cognitive status.
In each case the correlation (+ or -) was in the anticipated direction.
Conclusions: This study is the first in the CFS literature to report
that plasma NPY is elevated compared to healthy controls and to a
fatigued comparison group, GWI patients. The significant correlations
of NPY with stress, negative mood, general health, depression and
cognitive function strongly suggest that this peptide be considered as
a biomarker to distinguish subsets of CFS.
Author: Mary Fletcher, Martin Rosenthal, Michael Antoni, Gail Ironson,
Xiao Zeng, Zachary Barnes, Jeanna Harvey, Barry Hurwitz, Silvina
Levis, Gordon Broderick, Nancy Klimas
Behavioral and Brain Functions 2010, 6:76