So yeah, anyone know anything about attachment disorders?

So I guess I'm just wondering about something and I was hoping I could find some answers here. So yeah, after about a year of meeting with my psychologist, psychiatrists and so forth, I've been sort of diagnosed. By which I mean I'm as close as I've been yet. So that's good I guess.
And yeah, after a long discussion it was confirmed that I'm dealing with some form of attachment difficulties and by such an attachment disorder. But I know a little about them and I know that attachment disorders such as Reactive Attachment Disorder and Disinhibited Attachment Disorder, well they're only diagnosed in young children. So yeah, I guess this is where I get to my question, well questions.

Exactly what is an attachment disorder? What happens when the child goes without treatment of an attachment disorder and gets older? And exactly how are attachment disorders treated?

Any assistance would be greatly appreciated, thank you in advance . It just all has me a little confused, very confused actually.

Good summary: Attachment Disorder, Attachment Therapy - Adult Attachment Disorder and Treatment

Good academic/professional paper: A Brief Overview of Adult Attachment Theory and Research | R. Chris Fraley

Thanks Perna, that was really helpful. I appreciate it .

I have heard that in some cases untreated reactive attachment disorder can become or share similarities to PTSD.

Wow. I knew this was an diagnosis for children but I had somehow assumed that as the person grew into adulthood that attachment problems would manifest as some other disorder like a personality disorder. Didn't know an adult could still be diagnosed with attachment disorder.