Jade,
This is my first post and I hope that it is coherent. This is a bit long and rambling, but you asked about breakdowns and all I can tell you is about my experience with my brother -- I'm not sure how helpful this will be, but here goes:
My brother had several breakdowns when he was in his early 30s, and it seemed that when he did so, he came to me. Sometimes he just showed up at my door, but a couple of times he called me (collect, of course!) in the middle of the night from several hundred miles away and threatened to kill himself.
Of course, at that time, I was not aware of who and what he was. My heart simply broke for him and so I would spend a great deal of energy and time trying to rally police, doctors, and hospitals to help him.
The second-last time my brother called me, I spoke with his psychiatrist who would not break confidentiality about my brother's on-going treatment (this is undoubtedly one of the most frustrating things about dealing with the mental health problems of family members). After a great deal of begging and pleading, the psychiatrist finally agreed to admit my brother to hospital, but told me that my brother had been caught lying and stealing from the nurses and other patients at the hospital in the past and it wouldn't be tolerated.
The good doctor also said, "Let me give you some advice: You don't need to worry about protecting your brother. He’ll always take care of himself first. Instead, you need to do everything you can to protect yourself and your family from him."
Of course, I didn't understand this advice at all.
The last time my brother had a breakdown (at least, it was the last time he called me), he was around 35 years old and he showed up at my door. He looked horrible and told me some very sad stories about his time in a psychiatric institution. I knew only that he was being treated for an eating disorder -- I thought that this was all that was wrong with him. He was very sad, and told me how horrible his life had been and how very much he wanted a new start. I thought we were on the verge of a breakthrough.
I fed him and cared for him for a couple of days and I contacted his psychiatrist (in another city a few hundred miles away) who finally agreed to re-admit my brother for treatment. I bought my brother a train ticket (afraid that if I gave him money for the train, he'd spend it elsewhere) and I physically put him on the train. My brother cried and hugged me and told me how much he appreciated the help. I thought that his life was finally on the right track.
Of course, when I returned home from the train station, I found that my wallet was nearly empty, my coin dish had disappeared, and some treasured jewellery items were missing. I spoke to the psychiatrist (briefly) several days later. My brother never showed up.
That was around 1981. Several years later when my brother died, I found copies of a psych assessment from yet another psychiatric institution among his personal papers: NPD with anti-social features. They might have had a tighter diagnosis if they’d have talked to family members.
My understanding is that psychopaths often burn out in mid-life and I’m quite sure that my brother was well on his way to a burn-out by the time he died. He did an awful lot of damage on the way through though.
At some level, I think he knew that this wasn't the life he wanted, but impulse control issues make it very difficult to engage in the kind of planning and effort it takes to pull things together. Grandiosity isn't always a recipe for success.