I don't have any information about that, but his father was abusive of him, both physically and emotionally. I believe that played a big part in it.
It is not possible to conduct a valid study in the present political climate, but my own informal studies prove to my satisfaction that the cause of SSAD is similar to that of PTSD.
That is, one or more overwhelming traumas.
In the case of SSAD, of course, that trauma is sexual in nature. For a boy, this would be a homosexual seduction or rape in the pre-adult years.