Chiropractic is a pseudoscientific[1] complementary and alternative medicine (CAM)[2] that is concerned with the diagnosis and treatment of mechanical disorders of the musculoskeletal system, especially the spine.[3] Chiropractors have proposed, especially those in the field's early history, that such disorders affect general health via the nervous system.[3] The main chiropractic treatment technique involves manual therapy, especially manipulation of the spine, other joints, and soft tissues, but may also include exercises and health and lifestyle counseling.[4] Chiropractors are not physicians or medical doctors.[5][6]Systematic reviews of controlled clinical studies of treatments used by chiropractors have not found evidence that chiropractic manipulation is effective, with the possible exception of treatment for back pain.[7] A critical evaluation found that collectively, spinal manipulation was ineffective at treating any condition.[8] Spinal manipulation may be cost-effective for sub-acute or chronic low back pain but the results for acute low back pain were insufficient.[9] The efficacy and cost-effectiveness of maintenance chiropractic care are unknown.[10] There is not sufficient data to establish the safety of chiropractic manipulations.[11] It is frequently associated with mild to moderate adverse effects, with serious or fatal complications in rare cases.[12] There is controversy regarding the degree of risk of vertebral artery dissection, which can lead to stroke and death, from cervical manipulation.[13] Several deaths have been associated with this technique[12] and it has been suggested that the relationship is causative,[14][15] a claim which is disputed by many chiropractors.[15]Chiropractic is well established in the United States, Canada, and Australia.[16] It overlaps with other manual-therapy professions such as osteopathy and physical therapy.[17] Most who seek chiropractic care do so for low back pain.[18] Back and neck pain are considered the specialties of chiropractic, but many chiropractors treat ailments other than musculoskeletal issues.[7] Many chiropractors describe themselves as primary care providers,[7][19] but the chiropractic clinical training does not support the requirements to be considered primary care providers.[3] Chiropractic has two main groups: "straights", now the minority, emphasize vitalism, "innate intelligence", and consider vertebral subluxations to be the cause of all disease; "mixers", the majority, are more open to mainstream views and conventional medical techniques, such as exercise, massage, and ice therapy.[20]D. D. Palmer founded chiropractic in the 1890s,[21] after saying he received it from "the other world";[22] Palmer maintained that the tenets of chiropractic were passed along to him by a doctor who had died 50 years previously.[23] His son B. J. Palmer helped to expand Chiropractic in the early 20th century.[21] Throughout its history, chiropractic has been controversial.[24][25] Its foundation is at odds with mainstream medicine, and has been sustained by pseudoscientific ideas such as subluxation and innate intelligence.[26] Despite the overwhelming evidence that vaccination is an effective public health intervention, among chiropractors there are significant disagreements over the subject,[27] which has led to negative impacts on both public vaccination and mainstream acceptance of chiropractic.[28] The American Medical Association called chiropractic an "unscientific cult" in 1966[29] and boycotted it until losing an antitrust case in 1987.[19] Chiropractic has had a strong political base and sustained demand for services; in recent decades, it has gained more legitimacy and greater acceptance among conventional physicians and health plans in the United States.[19]