https://www.vox.com/2015/4/2/8330925/morgellons :
Interestingly, a large number of people in the study had a psychiatric or addictive condition, including depression and drug use. Among half of the participants in the study used drugs, but it wasn't clear whether the drugs caused the symptoms or whether they were being used to deal with the disease.
Even so, the researchers could not uncover any particular underlying medical condition or infectious source, and concluded that Morgellons is "similar to more commonly recognized conditions such as delusional infestation."
