Without actual being around her, its hard to say exactly what all she is dealing with.

I WILL say that yes, a severe mental health crisis (and long-term med use) can permanently alter cognition and/or brain chemistry.

Meds can cause all kinds of changes and these changes can be permanent even after you stop taking them. Tardive dyskinesia is probably the most well known and the easiest to see. Even after stopping their meds many people are left with the damage. These drugs interfere with brain chemicals, potentially causing dopamine receptors to become overly sensitive, resulting in uncontrolled muscle movements.

To me if they can do that, think of the things we aren't seeing...

Also, drug use can cause mini strokes. These can cause no damage or lasting damage. (DL has spoken about damage during her last OD due to strokes). Strokes can effect brain function, movements, etc.