The precise cause of BFS is unknown, and it is not known if it is a disease of the motor nerves, the muscles, or the neuromuscular junction. Though twitching is sometimes a symptom of serious diseases such as spinal injury, muscular dystrophy, Lyme disease, Creutzfeldt–Jakob disease (CJD), neurofibromatosis or amyotrophic lateral sclerosis (ALS), causes like over-exertion are more common. Mitsikostas et al. found that fasciculations "were slightly correlated to the body weight and height and to the anxiety level" in normal subjects.[6]