Fibromyalgia (FM) is a prevalent disorder defined by the presence of chronic widespread pain in
association with fatigue, sleep disturbances and cognitive dysfunction. Recent studies indicate that bipolar
spectrum disorders frequently co-occur in individuals with FM. Furthermore, shared pathophysiological
mechanisms anticipate remarkable phenomenological similarities between FM and BD. A comprehensive
search of the English literature was carried out in the Pubmed/MEDLINE database through May 10th, 2015 to
identify unique references pertaining to the epidemiology and shared pathophysiology between FM and bipolar
disorder (BD). Overlapping neural circuits may underpin parallel clinical manifestations of both disorders.
Fibromyalgia and BD are both characterized by functional abnormalities in the hypothalamic-pituitary-adrenal
axis, higher levels of inflammatory mediators, oxidative and nitrosative stress as well as mitochondrial
dysfunction. An over-activation of the kynurenine pathway in both illnesses drives tryptophan away from the
production of serotonin and melatonin, leading to affective symptoms, circadian rhythm disturbances and
abnormalities in pain processing. In addition, both disorders are associated with impaired neuroplasticity (e.g.,
altered brain-derived neurotrophic factor signaling). The recognition of the symptomatic and pathophysiological
overlaping between FM and bipolar spectrum disorders has relevant etiological, clinical and therapeutic
implications that deserve future research consideration.
Keywords: Bipolar disorder, fibromyalgia, inflammation, oxidative stress, brain-derived neurotrophic factor,
hypothalamic-pituitary adrenal axis, neuroimaging, pathophysiology, psychiatry, neurology.
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