Chiropractic is about treating the person, not a particular body part. While this profession has been closely associated with low back pain, that is just one symptom that a balanced frame and clear nerve system helps to improve. In fact, chiropractic psychiatric hospitals existed that helped patients with mental illness.
From the 1920s to 1960s, multiple chiropractic sanitariums existed to treat mental illness. The most well know were Clear View and Forest Park. The history is fascinating, check our the article for more information.