Fibromyalgia is associated with mental health issues like anxiety, posttraumatic stress disorder, bipolar disorder, and depression. Patients with fibromyalgia are five times more likely to have major depression than the general population.Fibromyalgia and numerous chronic pain conditions frequently coexist. These include chronic tension headaches, myofascial pain syndrome, and temporomandibular disorders. Multiple sclerosis, post-polio syndrome, neuropathic pain, and Parkinsons disease are four neurological disorders that have been linked to pain or fibromyalgia. Fibromyalgia largely overlaps with chronic fatigue syndrome and may share the same pathogenetic mechanisms.Comorbid fibromyalgia has been reported to occur in 20–30% of individuals with rheumatic diseases. It has been reported in people with noninflammatory musculoskeletal diseases.The prevalence of fibromyalgia in gastrointestinal disease has been described mostly for celiac disease and irritable bowel syndrome (IBS). Fibromyalgia has also been linked with obesity. Other conditions that are associated with fibromyalgia include an overactive bladder. Risk factors
The cause of fibromyalgia is unknown. However, several risk factors, genetic and environmental,  have been identified. Genetics
Genetics play a major role in fibromyalgia, and may explain up to 50% of the disease susceptibility. Fibromyalgia is potentially associated with polymorphisms of genes in the serotoninergic, dopaminergic and catecholaminergic systems. Several genes have been suggested as candidates for susceptibility to fibromyalgia. These include SLC64A4, TRPV2, MYT1L, NRXN3, and the 5-HT2A receptor 102T/C polymorphism.
Pathophysiology
Without the enzymatic activity of Malonyl-CoA decarboxylase, cellular Mal-CoA increases so dramatically that at the end it is instead broken down by an unspecific short-chain acyl-CoA hydrolase, which produces malonic acid and CoA. Malonic acid is a Krebs cycle inhibitor, preventing the cells to make ATP through oxidation. In this condition, the cells, to make ATP, are forced to increase glycolysis, which produces lactic acid as a by-product. The increase of lactic and malonic acid drastically lowers blood pH, and causes both lactic and malonic aciduria (acidic urine). This condition is very rare, as fewer than 20 cases have been reported. By 1999, only seven cases of Malonyl- CoA decarboxylase deficiency had been reported in human in Australia; however, this deficiency predominately occurs during childhood. Patients from the seven reported cases of Malonyl- CoA decarboxylase deficiency have an age range between 4 days to 13 years, and they all have the common symptom of delayed neurological development.